AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PUEBLO CO
407 AM MST SUN JAN 20 2008
.SHORT TERM...
(TODAY AND TONIGHT)
CURRENTLY...WATER VAPOR IMAGERY AND RUC MODEL UPPER AIR ANALYSES
SHOWED THE NEXT AREA OF LOW PRESSURE CONTINUING TO DIG OVER THE
PACIFIC NORTHWEST. 08Z/20 MSAS WIND/POTENTIAL TEMPERATURE ANALYSIS
HAD THE FRONTAL BOUNDARY WELL TO THE NORTH AND EAST OF SOUTHERN CO
EARLY THIS MORNING. COLD AIR CONTINUES TO BE TRAPPED IN THE LOWER
ELEVATIONS/VALLEYS. THE "BANANA-BELT"...INVERSION AREA...HAD
TEMPERATURES IN THE 20S/30S BETWEEN 6K-9K FT MSL LAYER ALONG AND
WEST OF I-25 CORRIDOR JUXTAPOSED WITH SINGLE DIGITS IN VALLEYS. ANY
"SIGNIFICANT" WINDS ARE AROUND MOUNTAIN TOP LEVEL AND ALONG THE
RATON MESA INTO FAR SOUTHEAST CO. SOME PERSISTENT SCT-BKN MOUNTAIN
WAVE CI/CS HAS BEEN OVER PIKES PEAK/PALMER DIVIDE EARLY THIS
MORNING.
TODAY...SHOULD BE A RELATIVELY QUIET DAY. BIG TEMPERATURE FORECAST
CHALLENGES...ESPECIALLY THE LOWER ELEVATIONS. MODERATE WESTERLY
(CHINOOK) FLOW ALOFT SHOULD PERSIST OVER THE CENTRAL ROCKIES. THE
HIGHER ELEVATIONS SHOULD SEE BRISK/WINDY CONDITIONS. THE GREATEST
HIGH TEMPERATURE CHALLENGE WILL BE IN THE LOWER AR RIVER AND SAN
LUIS VALLEYS. IF THE WIND CANNOT PICK UP...THEN THE SHALLOW COLD AIR
COULD REMAIN TRAPPED. MODERATELY UNSTABLE MIDLEVEL LAPSE RATES COULD
LEAD TO A LITTLE MORE MIXING BY THIS AFTERNOON. 06Z/20 12KM NAM-WRF
WANTS TO KEEP THE LOW LEVEL COLD AIR WEDGED INTO THE VALLEY AS
RELATIVELY LIGHT EAST-SOUTHEAST WINDS DEVELOP FROM LHX-LAA. HIGHS
APPROACHING 40F MIGHT BE A STRETCH IN THIS AREA THIS AFTERNOON.
EXTREMELY TOUGH CALL FOR THE SAN LUIS VALLEY CENTER FLOOR...
ALAMOSA...THIS AFTERNOON. CURRENT FORECAST LOOKS CLOSE. ANY
PRECIPITATION CHANGES WOULD BE VERY LOW AND AROUND THE CENTRAL
MOUNTAINS CONTINENTAL DIVIDE REGION.
TONIGHT...WHEN WILL THE COLD FRONT RACE ACROSS EASTERN CO IS THE
BIGGEST QUESTION. THE LATEST 12KM NAM-WRF...13KM RUC...AND GFS WANT
TO HOLD OFF THE FRONTAL BOUNDARY MOVING ACROSS EAST CENTRAL AND
SOUTHEAST CO UNTIL MONDAY MORNING. THIS FRONTAL BOUNDARY WILL BE
VERY SHALLOW...SURFACE-800MB...GIVEN THE RELATIVELY DEEP
WEST-SOUTHWEST FLOW AT 750MB AND ABOVE. I GUESS THERE IS A CHANCE
THE COLD FRONT/CP AIR MASS COULD "WEDGE" DOWN THE CO FRONT RANGE
DURING THE NIGHT...TOUCH CALL. AS FOR PRECIPITATION...THERE COULD BE
A CHANCE...MAINLY ACROSS THE CENTRAL MOUNTAINS...NEAR THE RELATIVELY
DEEPER MOISTURE LAYER...BUT FURTHER SOUTH ACROSS SOUTHERN CO...THE
700-300MB LAYER IS MUCH DRIER IN THE SOUTHWEST FLOW. FOR THE I-25
CORRIDOR AND SOUTHEAST CO PLAINS...ANY PRECIPITATION CHANCES ALL
DEPEND ON WHERE THE SHALLOW FRONTAL BOUNDARY LIES. ALSO...THE
MOISTURE LAYER WILL BE SO SHALLOW AND JUXTAPOSED WITH MUCH DRIER AIR
ALOFT...SO ANY POTENTIAL FOR "SEEDER-FEEDER" PRECIPITATION FROM
ALOFT WILL BE EXTREMELY LIMITED. DEPENDING ON THE SURFACE
TEMPERATURE...THERE COULD BE THE POTENTIAL FOR SOME VERY LIGHT
SNOW...FREEZING DRIZZLE...OR DRIZZLE (AND FOG) DIRECTLY BEHIND THE
FRONTAL BOUNDARY. IF THE SURFACE WINDS ARE NORTH-NORTHEASTERLY...
THEN ANY PRECIPITATION CHANCE WOULD BE ALONG THE PALMER DIVIDE
HIGHER TERRAIN OVER TO LIMON. ALONG AND JUST NORTH OF HIGHWAY 50
ACROSS THE SOUTHEAST CO PLAINS...NORTHERLY WINDS ARE A DOWNSLOPE
COMPONENT. THERE IS SOME 900MB-700MB FRONTOGENETICAL(IMPLIED LIFT)
FORCING JUST BEHIND THE FRONT TO POSSIBLY SQUEEZE OUT SOME
PRECIPITATION...BUT AGAIN...JUST ABOVE THIS SHALLOW COLD/MOIST LAYER
SHOULD BE MUCH DRIER AIR. METZE
.LONG TERM...
(MONDAY THROUGH SATURDAY)
PRIMARY METEOROLOGICAL CHALLENGES FOR THE LONG TERM INCLUDE BELOW
SEASONAL TEMPERATURES CONTINUING AT LEAST UNTIL THURSDAY MORNING
AND GENERALLY LOW GRADE POPS AT TIMES...ESPECIALLY OVER THE
WESTERN HIGHER TERRAIN REGION FROM LATER THURSDAY INTO SATURDAY.
OVERALL...LATEST LONGER TERM MODELS CONTINUE TO BACK OFF ON
WIDESPREAD PRECIPITATION POTENTIAL OVER EASTERN
SECTIONS...ESPECIALLY FROM TUESDAY INTO SATURDAY AS ZONAL TO UPPER
RIDGING FLOW NOTED OVER CWFA FROM MONDAY INTO THURSDAY AND THEN
MOIST SOUTHWEST TO ZONAL FLOW ALOFT DEVELOPS FROM LATER THURSDAY
INTO SATURDAY.
THIS MOIST FLOW SHOULD ENHANCE PRECIPITATION CHANCES OVER THE
CENTRAL AND WESTERN MOUNTAINS FROM LATER THURSDAY INTO SATURDAY.
IN ADDITION...GUSTY WINDS MAY BECOME AN ISSUE FROM THURSDAY NIGHT
INTO SATURDAY.
FINALLY...TEMPERATURES PROJECTED TO CONTINUE TO RUN BELOW
CLIMATOLOGICAL AVERAGES FROM MONDAY INTO AT LEAST THURSDAY
MORNING WITH INDICATIONS THAT TEMPERATURES MAY ATTEMPT TO REBOUND
BY LATE WEEK.
&&
.AVIATION...
PER SHORT TERM DISCUSSION...VFR CONDITIONS WILL BE LIKELY AT ALS AND
PUB THROUGH 12Z/21.  VFR CONDITIONS ARE ANTICIPATED FOR COS WITH A
COLD FRONTAL PASSAGE BETWEEN 09Z/21-12Z/21. METZE
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
</pre> co
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
833 PM EST SUN JAN 20 2008
.SYNOPSIS...
AN ARCTIC AIR MASS WILL CONTINUE TO IMPACT UPSTATE NEW YORK AND NEW
ENGLAND OVERNIGHT.  PERIODS OF HEAVY LAKE EFFECT SNOW SHOWERS
DOWNWIND OF LAKE ONTARIO WILL OCCUR THROUGH MONDAY MORNING. HIGH
PRESSURE WILL BUILD IN FROM THE MIDWEST TO THE ATLANTIC SEABOARD
THROUGH MONDAY. A WEATHER DISTURBANCE WILL MOVE FROM THE EASTERN
GREAT LAKES THROUGH THE SAINT LAWRENCE VALLEY ON TUESDAY...WITH
ANOTHER WEAK DISTURBANCE WEDNESDAY NIGHT. THESE DISTURBANCES WILL BE
FOLLOWED BY A REINFORCING SHOT OF ARCTIC AIR FOR THURSDAY AND FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MONDAY/...
THE LATEST 13KM RUC SHOWS A 500 MB SHORT WAVE MOVING ACROSS LAKE
ONTARIO.  THIS SHORT WAVE IS HAS SHIFTED THE SINGLE LAKE EFFECT BAND
SOUTHWARD OVER THE PAST 3 HOURS WITH MORE OF A 290 DEGREE
TRAJECTORY.  THE LOCAL RADARS SHOW THE BAND BEING DISRUPTED...AND
ITS DOWNSTREAM EXTENSION INTO HERKIMER AND WRN HAMILTON COUNTIES HAS
WEAKENED A BIT.  HOWEVER...THE LATEST NAM12 AND BUFKIT PROFILES DO
SHOW THE BAND REINTENSIFYING AND LIFTING BACK NORTH BETWEEN RTE 29
AND RTE 8 IN HERKIMER COUNTIES MONDAY MORNING. IT MAY EVEN GET AS
FAR NORTH AT RT 28 AND OLD FORGE BY DAYBREAK.
WE ADJUSTED HOURLY DEWPOINTS IN THE GRIDS BASED ON OBSERVATIONS.
THE DEWPOINTS ARE GENERALLY 0 TO 5 BELOW.  THE DRY AIR MASS IS
PREVENTING THE LAKE BAND SNOWS GETTING TO FAR DOWN THE MOHAWK RIVER
VALLEY. WE DID PLACE A SLIGHT CHANCE OF SNOW SHOWERS INTO THE
CAPITAL REGION PRIOR TO MIDNIGHT...AND KEPT FLURRIES IN THE CAPITAL
REGION AFTER MIDNIGHT.  WE ALSO RAISED POPS TO HIGH CHANCE AND LOW
LIKELY VALUES FOR THE SRN GREEN MTNS...DUE TO THE FAVORABLE 270-290
DEGREE LOW LEVEL TRAJECTORY.  THE FLOW WILL BACK BETWEEN 06Z-12Z
WITH THE BAND LIFTING BACK TO THE NORTH IN THE EXTREME
INSTABILITY...AND THE INVERSION HEIGHTS AROUND 10 KFT.
GROUND TRUTH INDICATES ABOUT 2 TO 6 INCHES HAVE FALLEN THUS FAR. AS
A RESULT...WE HAVE KEPT THE SNOWFALL TOTALS THE SAME...6-12 INCHES
IN HERKIMER COUNTY AND 5 TO 10 IN HAMILTON COUNTY.
THE WINDS HAVE DECREASED TO AROUND 10 KTS...AND APPARENT TEMP HOURLY
GRIDS STILL YIELD WIND CHILLS BELOW ADVISORY THRESHOLD.  WE EXPECT
THE WINDS TO BRIEFLY INCREASE WITH THE SHORT WAVE PASSAGE...BUT THEN
BEGIN TO SUBSIDE WITH SFC HIGH PRESSURE NOSING IN FROM THE SOUTH AND
WEST.
&&
.SHORT TERM /6 AM MONDAY THROUGH TUESDAY NIGHT/...
LAKE EFFECT SNOW BAND WILL STILL BE OVER THE WARNED AREAS DURING THE
MORNING...BUT DURING THE AFTERNOON AS WINDS THROUGH THE BOUNDARY
LAYER WEAKEN AND SHIFT TO A MORE SOUTHWEST TYPE FLOW...THE SNOW BAND
WILL GRADUALLY WEAKEN AND RETREAT NORTHWARD. HIGHS MONDAY WILL BE IN
THE TEENS NORTH TO LOWER/MID 20S SOUTH. CLOUD COVER SHOULD BE
LARGELY CONFINED TO AREAS DOWNWIND OF THE LAKE.
SURFACE HIGH WILL PASS OUT TO SEA OFF THE MID ATLANTIC STATES MONDAY
NIGHT. THIS WILL ALLOW A SOUTHERLY FLOW TO DEVELOP ACROSS THE
REGION...SO TEMPS NOT EXPECTED TO DROP THAT MUCH. LOWS MONDAY NIGHT
HAVE GENERALLY BEEN FORECAST BETWEEN 5 AND 10 DEGREES. THE LOWS
MONDAY NIGHT MAY OCCUR EARLY DURING THE NIGHT IN MANY LOCATIONS...
ESPECIALLY HIGHER TERRAIN LOCATIONS. CLOUDS AHEAD OF THE NEXT SYSTEM
ARE LIKELY TO BEGIN TO OVERSPREAD THE REGION LATE AT NIGHT.
TUESDAY AND TUESDAY NIGHT...NORTHERN STREAM ENERGY TRACKS ACROSS
THE REGION. SYSTEM RELATIVELY MOISTURE-STARVED...BUT GREAT LAKES
MOISTURE WILL GET ENTRAINED. STRONG SOUTHWESTERLY BOUNDARY LAYER
FLOW WILL SET UP...INCREASING THE ISENTROPIC LIFT AND FRONTOGENESIS.
EVEN THOUGH OVERCAST WITH LIGHT SNOW LIKELY...SOUTH/SOUTHWEST
SURFACE WINDS AND SOME MIXING SHOULD GET TEMPERATURES INTO THE 20S
TO AROUND 30. SNOW EXITS BY TUESDAY EVENING WITH NO MORE THAN ABOUT
TWO INCHES EXPECTED...AND SOMEWHAT COLDER AIR BEGINS TO WORK BACK
INTO THE REGION LATER TUESDAY NIGHT.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
MAINLY DRY BUT COLD WEATHER EXPECTED FOR MUCH OF THE EXTENDED
FORECAST PERIOD AS NORTHERN STREAM DOMINATES OUR WEATHER...
THUS ONLY WEAK CLIPPER TYPE SYSTEMS AND SOME LAKE EFFECT TO DEAL
WITH AS NO INTERACTION WITH THE SOUTHERN STREAM EXPECTED. WED LOOKS
MAINLY DRY...EXCEPT FOR SOME LAKE EFFECT ACTIVITY ACROSS THE WESTERN
ADIRONDACKS WHICH WILL LINGER INTO WEDNESDAY EVENING. NEXT CLIPPER
WILL MOVE FROM THE UPPER GREAT LAKES THROUGH THE REGION WEDNESDAY
NIGHT...BRINGING A CHANCE OF LIGHT SNOW. VERY LITTLE QPF WITH SYSTEM
AND SYSTEM DOES NOT DEEPEN UNTIL IT IS WELL NORTHEAST OF FA IN
CANADIAN MARITIMES ON THURSDAY.
IN WAKE OF THE CLIPPER...ANOTHER PUSH OF ARCTIC AIR WILL BE MOVING
IN FOR THURSDAY AND FRIDAY. FLOW DIRECTION APPEARS TO BE N-NW...SO
LAKE EFFECT ACTIVITY EXPECTED TO REMAIN WEST OF FA FOR MOST OF THIS
PERIOD. A RIDGE OF HIGH PRESSURE WILL START TO BUILD ACROSS THE
REGION THURSDAY NIGHT INTO FRIDAY AND WITH COLD AIR ADVECTION AND
STILL ENOUGH OF A GRADIENT TO PRODUCE SOME LOW WIND CHILL VALUES
THURSDAY NIGHT INTO FRIDAY MORNING AND AGAIN FRIDAY NIGHT INTO
SATURDAY MORNING. AT THIS POINT WILL JUST INCLUDE A MENTION OF
HAZARDOUS WIND CHILL POSSIBLE LATE IN THE WEEK IN THE HWO AS EXACT
TIMING OF CONDITIONS IS STILL UNCERTAIN AT THIS POINT.
FOR NEXT WEEKEND THE RIDGE AXIS SHIFTS EAST OF THE AREA ON SATURDAY
AS ANOTHER CLIPPER TYPE SYSTEM MOVES ACROSS SOUTHERN CANADA...AND A
SOUTHWEST FLOW DEVELOPS. THIS SHOULD HELP BOOST TEMPS BACK TO MORE
SEASONABLE LEVELS AND BRING A CHANCE OF SNOW TO THE FA SATURDAY
AFTERNOON INTO SUNDAY.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE WILL CONTINUE TO BUILD IN FROM THE SOUTH AND WEST FROM
THE OH VALLEY.  VFR CONDITIONS WILL PREVAIL THE NEXT 24 HOURS FOR
KGFL/KALB/KPOU.  LAKE EFFECT SNOWS WILL CONTINUE WEST OF THE HUDSON
RIVER VALLEY.  SCT-BKN CLOUDINESS 5-6 KFT MAY OCCUR AT KGFL SOUTH TO
KALB WITH A LAKE BAND SAGGING SOUTH FROM LAKE ONTARIO PRIOR TO 06Z.
THE WINDS WILL SUBSIDE A BIT TO AROUND 10 KTS FROM THE W/SW PRIOR TO
05Z.  AFTER MIDNIGHT...EXPECT THE WINDS TO LESSEN TO 5-10 KTS FROM
THE W/SW.  AFTER 13Z...SCT-BKN STRATOCUMULUS WILL RETURN WITH CIGS
IN THE 4-6 KFT RANGE. WE PLACED A VCSH FOR KGFL 13Z-18Z WITH THE
LAKE BAND LIFTING NORTHWARD INTO THE ADIRONDACK REGION BEFORE
DISSIPATING.  THE WINDS WILL BE GENERALLY FROM THE W/SW AT 10-15 KTS
WITH A FEW GUSTS AT KALB CLOSE TO 25 KTS.
OUTLOOK...
TUE...MVFR/IFR...CHANCE OF WIDESPREAD SNOW...LOW CIGS AND VSBY.
WED...MVFR/IFR EARLY AM...LOW CIGS/VSBY AND CHANCE OF LINGERING SHSN.
THU...VFR/MVFR...CHANCE OF -SHSN.
FRI...VFR...NO SIG WX.
&&
.HYDROLOGY...
NO HYDRO PROBLEMS ANTICIPATED FOR THE NEXT SEVERAL DAYS. ANY
PRECIPITATION THROUGH NEXT WEEK IS EXPECTED TO BE IN THE FORM OF
SNOW. SNOWPACK WILL BUILD ACROSS PORTIONS OF THE WESTERN
ADIRONDACKS...WITH POTENTIALLY SIGNIFICANT LAKE EFFECT SNOWS FALLING
THROUGH MONDAY. COLD AIRMASS IN PLACE WILL PERSIST THROUGH MUCH OF
THE WEEK...AND WILL RESULT IN RAPID FORMATION OF ICE AGAIN ON THE
MAIN STEM RIVERS IN THE HYDRO SERVICE AREA...SOME LOCATIONS ACROSS
NORTHERN PORTIONS OF THE HSA MAY BUILD ICE AT A RATE CLOSE TO AN
INCH A DAY.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...LAKE EFFECT SNOW WARNING UNTIL 1 PM EST MONDAY FOR NYZ032-033-
     038.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...TAW/GJM
NEAR TERM...TAW
SHORT TERM...GJM
LONG TERM...JSQ
AVIATION...TAW
HYDROLOGY...JSQ
</pre> ct
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
210 PM EST SUN JAN 20 2008
...FREEZE WARNING IN EFFECT FOR PORTIONS OF THE SUWANNEE VALLEY IN
FLORIDA...
.SHORT TERM...MSAS ANALYSIS SHOWS A STRONG 1040 MB HIGH HAS
SETTLED OVER THE OHIO AND TENNESSEE VALLEYS WITH AREA OF INFLUENCE
MUCH LARGER AND ENCOMPASSING ALL OF OUR FORECAST AREA. WINDS ON
THE EASTERN HALF OF THE HIGH HAVE GENERALLY BEEN IN THE 15 TO 20
MPH RANGE WITH LIMITED GUSTS THUS FAR. THIS SHOULD KEEP US SAFELY
BELOW ANY LAKE WIND CRITERIA THROUGH THIS EVENING. ALOFT...RUC
ANALYSIS STILL SHOWS SOUTHWEST FLOW BETWEEN 200 MB AND 300 MB AND
WATER VAPOR SHOWS SUFFICIENT MOISTURE FOR SCATTERED HIGH CLOUDS
ACROSS THE AREA. TEMPERATURES HAVE BEEN SLOW TO MODERATE DESPITE
PERIODS OF SUN DUE TO CONTINUED COLD AIR ADVECTION PATTERN. MOSTLY
TEMPS IN THE 40S AT THIS HOUR...WELL BELOW AVERAGE FOR ANY TIME OF YEAR.
MAIN FORECAST CHALLENGE TONIGHT WILL BE THE POTENTIAL FREEZE OVER
INLAND SECTIONS OF NORTHEAST FLORIDA. NORMALLY...WHEN GUIDANCE
INDICATES MIN TEMPS IN THE LOWER 20S...A FREEZE WARNING IS A GIVEN
ACROSS THAT AREA. HOWEVER...WITH WINDS REMAINING ELEVATED PER
SURFACE TO 1 KM NAM12 DEPICTION AND THE CONTINUED HIGH
CLOUDINESS...FEEL MOSGUIDE IS WAY TOO LOW FOR ITS MIN TEMP
TONIGHT. ALSO HAVE THE BENEFIT OF THE LAST FEW COLD AIR OUTBREAKS
WHICH WERE SIMILAR IN NATURE AND THE MOSGUIDE WAS TOO COLD ON
THOSE AS WELL.
WILL THEREFORE GO 5 DEGREES ABOVE GUIDANCE WITH THIS PACKAGE WHICH
STILL RESULTS IN FREEZE CONDITIONS OVER A PORTION OF THE SUWANNEE
VALLEY BUT EXCLUDES DUVAL AND NASSAU COUNTIES ALONG THE EAST
COAST. WILL ALSO BE WATCHING FOR A MARKED INCREASE IN LOW LEVEL
MOISTURE AND CLOUDS ALONG THE EAST COAST TOWARDS DAYBREAK AS
STRONG EASTERLY BOUNDARY LAYER WINDS TAKE HOLD. THIS ALL BEING
SAID...TEMPS WILL NEED TO MONITORED CLOSELY BY THE EVENING SHIFT
FOR POSSIBLE INCLUSION OF A FEW COUNTIES TO FREEZE WARNING.
MAIN DIFFERENCE IN MODELS THROUGH 12Z TUE IS THE DEGREE OF
SATURATION OF THE LOW LEVELS ADVERTISED BY THE MODELS. THE NAM12 IS
MUCH MORE AGGRESSIVE WITH MOISTURE RETURN WITH LOW END CHANCE POPS
ADVERTISED FOR THE ENTIRE SOUTHERN TIER LATE MON NIGHT. FEEL THERE
WILL BE MORE COLD AIR DAMMING AND RIDGING THAN MODEL INDICATE
WHICH SHOULD ALLOW FOR AN INVERTED TROUGH AND KEEP POPS CONFINED
CLOSER TO THE COAST INITIALLY.
MODEL DIFFERENCES CONTINUE INTO TUE EVENING AS GFS SHOWS A
SIGNIFICANT MID LEVEL DRY SLOT OVER THE AREA WHILE THE NAM12
ADVERTISES AND GOOD SLUG OF MOISTURE AND MID RANGE POPS INTO THE FL
PORTION. WILL USE A BLEND FOR NOW AND GO WITH LOW END SCATTERED
POPS WHICH MESHES WELL WITH PREVIOUS FORECAST AND ADJACENT GRIDS.
.LONG TERM...STRONG NORTHERN STREAM SHORTWAVE TO SCOUR OUT
MOISTURE BY 12Z WED WITH COOLER AND DRIER CONDITIONS EXPECTED BY
MIDWEEK. LAST FEW MODEL RUNS HAVE BEEN CONSISTENT IN SHOWING A
STRONG SURFACE HIGH DEVELOPING OVER THE MID SECTIONS OF THE
COUNTRY AND SHIFTING SOUTHWARD THROUGH THU. THIS HIGH SHOULD BUILD
IN PRIOR TO SIGNIFICANT MOISTURE INCREASE TO THE WEST. THIS WILL
ALLOW FOR A GENERALLY DRY AND COOL TO COLD PATTERN FOR THE END OF
THE WORK WEEK. NEXT SYSTEM WILL TAKE SHAPE EARLY SAT WITH YET
ANOTHER GULF LOW IN THE OFFING.
&&
.AVIATION...GENERALLY VFR CONDITIONS WILL CONTINUE. MAY BE SOME
PATCHY GROUND FOG PRIOR TO SUNRISE MON MORNING IN COASTAL NE FL
COUNTIES WITH INCREASING LOW-LEVEL MOISTURE FROM THE ATLC.
HOWEVER...NOT ENUF CERTAINTY TO MENTION ATTM.
&&
.MARINE...FCST APPEARS TO BE ON TRACK. HAVE EXTENDED OFFSHORE
SMALL CRAFT ADVISORY ANOTHER 6 HRS DUE TO LINGERING SWELLS THRU
TUE EVENING. MAY GO AHEAD AND UPGRADE RIP CURRENT RISK TO
MODERATE DUE TO BUILDING SEAS AND FLOW BECOMING MORE ONSHORE.
&&
.FIRE WEATHER...RED FLAG WARNING SHOULD EASILY VERIFY ACROSS NE
FL. SE GA WILL BE CLOSE...BUT SLOWLY RISING TEMPS AND LOWER THAN
EXPECTED WINDS MAY PREVENT RED FLAG CONDITIONS. HAVE OPTED TO
KEEP WARNING IN PLACE AS CRITERIA ONLY NEED TO BE MET BRIEFLY
PER NEW OPERATING PLAN. LOW-LEVEL MOISTURE WILL INCREASE ACROSS
THE AREA FOR MON.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG  27  54  36  66 /   0  10  10  20
SSI  37  52  47  64 /   0  10  10  30
JAX  34  54  47  69 /   0  10  20  30
SGJ  43  58  54  69 /   0  10  20  30
GNV  31  61  49  74 /   0  10  20  30
OCF  33  63  51  74 /   0  10  20  30
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...RED FLAG WARNING UNTIL 7 PM THIS EVENING FOR ALACHUA-BAKER-
     BRADFORD-CLAY-COLUMBIA-DUVAL-FLAGLER-GILCHRIST-HAMILTON-
     MARION-NASSAU-PUTNAM-ST JOHNS-SUWANNEE-UNION.
     FREEZE WARNING FROM 2 AM TO 9 AM MON FOR ALACHUA-BAKER-
     BRADFORD-COLUMBIA-GILCHRIST-HAMILTON-SUWANNEE-UNION.
GA...RED FLAG WARNING UNTIL 5 PM THIS AFTN FOR APPLING-
     ATKINSON-BACON-BRANTLEY-CHARLTON-CLINCH-COASTAL CAMDEN-
     COASTAL GLYNN-COFFEE-ECHOLS-INLAND CAMDEN-INLAND GLYNN-JEFF
     DAVIS-PIERCE-WARE-WAYNE.
AM...SMALL CRAFT ADVISORY UNTIL 10 PM TUE FOR ALTAMAHA SOUND
     GA TO FLAGLER BEACH FL 20 NM TO 60 NM OFFSHORE.
     SMALL CRAFT ADVISORY UNTIL 10 PM MON FOR ALTAMAHA SOUND
     GA TO FLAGLER BEACH FL OUT 20 NM.
&&
$$
DEESE/CARROLL/KEEGAN
</pre> fl
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MELBOURNE FL
1009 AM EST SAT JAN 19 2008
.DISCUSSION...FRONT APPEARS TO BE LOCATED NEAR CAPE CANAVERAL TO
TAMPA AS WARM SECTOR GRADUALLY EXPANDS NORTWARD THIS MORNING.
AREAS OF FOG WITH DENSE PATCHES NOW BEGINNING TO LIFT AND BREAK
UP AS VISIBILITIES CREEP UP TO ABOVE 3 MILES. EXPECT CONDITIONS TO
IMPROVE SIGNIFICANTLY BETWEEN 10 AND 11 AM. HOWEVER...SLOWER TO
IMPROVE ALONG THE FRONATL BOUNDARY AND JUST NORTH AS ASSOCIATED
WITH ADDITIONAL MULTI-LAYERED CLOUDINESS SO A LITTLE HARDER TO
GET THE MIXING THERE. LATEST PROFILER DATA SHOWS 25KT WINDS (SW)
DESCENDING TO BELOW 3KFT SO EXPECT ONCE ATMOSPHERE RECOUPLES...
SFC WINDS WILL BE ON THE GUSTY SIDE.
LATEST RUC13 SUGGESTS THAT FRONTAL BOUNDARY WILL STRUGGLE TO LIFT
MUCH FARTHER NORTH UNTIL LATER IN THE AFTERNOON BEFORE THE FULL
BREATHE OF THE SOUTHERLIES ARE FELT FORECAST AREA-WIDE. THIS MAY
REDUCE DIABATIC CONTRIBUTIONS EXCEPT FOR SOUTHERN COUNTIES ALREADY
SOUTH OF THE FRONT DISTRIBUTING THE GREATER INSTABILITY THERE.
NONETHELESS...SIGNIFICANT LOW LEVEL SHEAR INTRODUCED OVER NORTH
AREA A CONCERN FOR ASSOCIATED DEEP CONVECTION MOVING IN FROM THE
GULF. THIS...ALONG WITH INCREASING 850 MB WINDS...WILL KEEP A
CONCERN FOR STRONG CONVECTIVE WIND GUSTS FOR A FEW MARGINALLY
SEVERE STORMS THIS AFTERNOON.
&&
.AVIATION...LIFR COND GIVING WAY TO IFR TO EVENTUAL MVFR BY
17Z...ESPECIALLY TPA TO MLB NORTHWARD. WINDS ABOVE THE SURFACE ARE
INCREASING TO 20-25 KT AROUND 15KFT BEAR WATCHING FOR SFC WIND
GUSTS TO COMPARABLE SPEEDS AS THE DAY WEARS.
&&
.MARINE...FORECAST APPEARS ON TRACK. UPDATES NOT EXPECTED. SEE
PREVIOUS DISCUSSION.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB  74  44  55  44 /  60  70   0   0
MCO  78  48  58  44 /  60  70   0   0
MLB  81  52  59  52 /  40  60   0   0
VRB  85  56  62  53 /  40  60  10  10
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...FIRE WEATHER WATCH SUNDAY AFTERNOON FOR INLAND VOLUSIA-NORTHERN
     LAKE-ORANGE-SEMINOLE-SOUTHERN LAKE.
AM...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 5 PM EST MONDAY
     FOR COASTAL WATERS FROM FLAGLER BEACH TO VOLUSIA BREVARD
     COUNTY LINE OUT 20 NM-COASTAL WATERS FROM VOLUSIA BREVARD
     COUNTY LINE TO SEBASTIAN INLET OUT 20 NM.
     SMALL CRAFT ADVISORY UNTIL 5 PM EST MONDAY FOR COASTAL WATERS
     FROM SEBASTIAN INLET TO JUPITER INLET OUT 20 NM-WATERS FROM
     FLAGLER BEACH TO VOLUSIA BREVARD COUNTY LINE 20 TO 60 NM
     OFFSHORE-WATERS FROM SEBASTIAN INLET TO JUPITER INLET 20 TO
     60 NM OFFSHORE-WATERS FROM VOLUSIA BREVARD COUNTY LINE TO
     SEBASTIAN INLET 20 TO 60 NM OFFSHORE.
&&
$$
SHORT TERM...DW
LONG TERM....RL
AVIATION...99
</pre> fl
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
1218 AM EST SUN JAN 20 2008
.SYNOPSIS...
LOW PRESSURE WILL MOVE NORTHEASTWARD ALONG THE CAROLINA
COAST TONIGHT...AND BE WELL NORTHEAST OF THE AREA SUNDAY.
HIGH PRESSURE WILL MOVE INTO THE REGION SUNDAY WITH MOSTLY SUNNY
SKIES AND LIGHT WINDS.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
PRECIPITATION IS COMING TO AN END ACROSS THE REGION AS THE SURFACE
LOW IS LIFTING OFF THE FLORIDA COAST AND AN ARCTIC COLD FRONT
APPROACHES FROM THE NORTHWEST. THROUGH MIDNIGHT THERE MAY BE AREAS
OF FLURRIES NORTH OF I-20 WITH SPRINKLES OR ISOLATED RAIN SHOWERS
SOUTH OF THIS LINE. THERE WERE SOME REPORTS OF A LIGHT DUSTING IN
THE ADVISORY AREA BUT NO ADDITIONAL ACCUMULATION IS EXPECTED AND
HAVE ALLOWED THE ADVISORY TO EXPIRE.
BACK EDGE OF THE CLEARING LINE RAPIDLY APPROACHING THE UPSTATE AND
SHOULD ARRIVE IN THE MIDLANDS BETWEEN 06Z-08Z...FOLLOWED BY
MODERATE COLD ADVECTION AS THE SURFACE FRONT PUSHES THROUGH.
CONSIDERED THE POSSIBILITY OF NEEDING A SPECIAL WEATHER STATEMENT
FOR REFREEZING OF WATER ON ROADWAYS BUT THE SLOW ARRIVAL OF THE
SUBFREEZING AIR AND RELATIVELY WARM GROUND SURFACES AS NOTED BY SC
DOT OBSERVATIONS...AND A PERSISTENT WIND OVERNIGHT...LED US TO
REFRAIN FROM ISSUING ANYTHING.
GRIDDED DATABASE HAS BEEN UPDATED AND SENT TO NDFD WITH LITTLE
CHANGES TO GRIDS OTHER THAN POPS AND WEATHER AND HOURLY
TEMPERATURES TO ACCOUNT FOR LATEST TRENDS.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/...
LOW PRESSURE WILL CONTINUE TO TRACK FURTHER INTO THE ATLANTIC
BASIN AS HIGH PRESSURE BUILDS IN FROM THE WEST. NORTHWEST WINDS
THROUGH THE DAY WILL USHER IN COOLER AND DRIER AIR WITH MOSTLY
SUNNY SKIES THROUGH THE DAY. TEMPERATURES WILL REBOUND SLIGHTLY
DURING THE DAY DUE TO THE SUNSHINE...HOWEVER SUNDAY NIGHT WITH
CLEAR SKIES AND DRY AIR OVER THE REGION TEMPERATURES WILL DROP
INTO THE UPPER TEENS TO LOWER 20S.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
MONDAY APPEARS TO REMAIN DRY.  NEXT WEATHER MAKER WILL ARRIVE ON
TUESDAY. THIS WILL BEGIN A RATHER ACTIVE WEATHER PERIOD FROM
TUESDAY THROUGH SATURDAY...WITH TWO OR THREE SYSTEMS MOVING
THROUGH THE REGION DURING THAT TIME FRAME. TEMPERATURES DURING THE
LONG TERM PERIOD APPEAR TO REMAIN WARM ENOUGH SO THAT EACH EVENT
WILL BE ALL RAIN. TEMPERATURES EXPECTED TO REMAIN AT OR BELOW
CLIMATE NORMALS THROUGH THE PERIOD.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
DRYING WILL OCCUR AS LOW PRESSURE MOVES AWAY FROM THE AREA. EXPECT
MAINLY IFR CEILINGS EARLY IN THE TAF PERIOD BUT VFR CONDITIONS
SHOULD DEVELOP BY 09Z. BASED THIS FORECAST ON THE LATEST RUC SHOWING
MOISTURE BECOMING VERY SHALLOW PLUS MIXING ASSOCIATED WITH HIGH
PRESSURE BUILDING INTO THE REGION. SATELLITE TRENDS SUPPORT THIS
FORECAST. THE DRY AIR MASS MOVING INTO THE REGION WILL DOMINATE
THROUGH THE REST OF THE TAF PERIOD.
NO SIGNIFICANT IMPACTS EXPECTED DURING THE EXTENDED PERIOD.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
</pre> ga
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1257 AM EST SUN JAN 20 2008
.AVIATION...
LAKE EFFECT SNOW IS STILL MOVING THROUGH SBN. CONDITIONS THERE
SHOULD REMAIN LOW AS THE SNOW CONTINUES THROUGH THE NIGHT. THE
LAKE EFFECT SNOW IS EXPECTED TO END BY LATE MORNING WITH CLOUDS
SCATTERING OUT BY THE AFTERNOON. VFR CONDITIONS WILL THEN
PREVAIL THROUGH THE AFTERNOON INTO THE EVENING HOURS. THE PRESSURE
GRADIENT WILL WEAKEN TOWARDS LATE AFTERNOON/EARLY EVENING HOURS
ALLOWING THE WIND TO DECREASE IN SPEED. FWA WILL BE VFR FOR THIS
ENTIRE TAF PERIOD. JUST SOME MID LEVEL CLOUDS TOWARDS THE END OF
THIS TAF PERIOD FOR BOTH SITES WITH SOME MID LEVEL MOISTURE MOVING
INTO THE AREA.
&&
.UPDATE... /ISSUED 808 PM EST SAT JAN 19 2008/
HAVE MADE SOME SIGNIFICANT CHANGES THIS PERIOD...WITH REPORTS
FROM OBSERVERS ACROSS THE PREFERRED LAKE EFFECT REGION IT IS
FAIRLY OBVIOUS THAT WE ARE FALLING SHORT OF THE CRITERIA FOR THE
LAKE EFFECT ADVISORY. HAVE ENDED IT...AND EXTENDED THE WIND CHILL
ADVISORY FOR THE OVERNIGHT HOURS INTO THOSE COUNTIES. HAVE
SLIGHTLY LOWERED TEMPS SOME. OMEGAS CONTINUE THROUGH THE NIGHT OFF
THE LAKE...BUT THE VERY DRY ARCTIC AIR HAS LIMITED THE MOISTURE
AND THE AMOUNTS. THOUGH LIGHT SNOW WILL CONTINUE ACROSS THE
NORTHWESTERN PORTIONS OF THE AREA...AMOUNTS WILL BE WELL LESS THAN
3 INCHES IN THE NEXT 12 HOURS...AND THEREFORE ALLOWING THE
CANCELING OF THE ADVISORY. ROADS WILL STILL BE DIFFICULT TO TRAVEL
IN SPOTS WITH THE SNOWFALL...BUT THE SNOW SHOULD BE FAIRLY POWDERY
AND BLOWING AND DRIFTING SOME WITH THE 10-15KT WINDS LIKELY THRU
MUCH OF THE NIGHT.
&&
.PREV DISCUSSION... /ISSUED 459 PM EST SAT JAN 19 2008/
SHORT TERM...TONIGHT AND TOMORROW.
ARCTIC HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE REGION...
COLD ARCTIC AIR IN PLACE WILL CONTINUE TO SUPPORT LAKE EFFECT SNOW
SHOWERS TONIGHT. SATELLITE/RADAR/AND SFC OBS CONFIRM LAKE SNOWS
CONTINUING ACROSS PORTIONS OF NORTHERN IN AND SOUTHERN MI. FARTHER
AWAY FROM THE LAKE...LAKE MODIFIED AIRMASS IN PLACE HAS SUPPORTED
THE DEVELOPMENT OF DIURNAL CU AND LIGHT SNOW FROM AREAS EAST OF A
WARSAW-HILLSDALE LINE. FORECAST MODELS HAVE A GOOD HANDLE OF THE AIR
MASS IN PLACE...WITH THE GFS DISPLAYING A SLIGHTLY BETTER HANDLE OF
BAROCLINIC ZONES AND H925 TEMPS. HAVE TAILORED THE SHORT TERM
PACKAGE MAINLY TO GFS AND RUC 13.
TONIGHT...WEAK SHORTWAVE TROUGH OVER PORTIONS OF IA WILL SWING INTO
THE REGION AND FORCING WEAK LARGE SCALE ASCENT...SUPPORTING A BRIEF
RAISE IN INVERSION HEIGHTS OVER THE LAKE. THIS COMBINED WITH
ONGOING CAA WILL SUPPORT LAKE INDUCED CAPES OF AROUND 400
J/KG...MAINLY THIS EVENING AND EARLY MORNING...BEFORE INVERSION
HEIGHTS RAPIDLY FALL AND SUBSTANTIALLY DRY AIR ADVECTS INTO THE
REGION AROUND H925-H850. GIVEN DRY AIR IN PLACE...EXTREMELY COLD
AIRMASS WITH SMALL CRYSTAL FORMATION FAVORED...AND 290 DEGREE
FETCH...EXPECTING SNOW ACCUMS TO BE ON THE LIGHT SIDE OF 1-3 INCHES
WITH LOCALLY HEAVIER AMOUNTS UP TO 4 INCHES INTO SUNDAY MORNING.
HAVE ALLOWED THE WINTER WEATHER ADVISORY TO CONTINUE GIVEN SNOW
ACCUMS...BRISK WINDS OF 15 TO 25 CREATING DANGEROUS WIND CHILLS OF
15 TO 20 BELOW...AND BLOWING/DRIFTING SNOW POTENTIAL.
ELSEWHERE AWAY FROM THE LAKE...EXPECT A BITTER COLD NIGHT WITH
MOSTLY CLEAR SKIES AND COLD TEMPS. EXPECTED LOWS OF ZERO TO 5 BELOW
AND WINDS OF 15 TO 25 MPH WILL SUPPORT DANGEROUS WIND CHILLS OF 15
TO 25 BELOW ZERO.
LOOK FOR ANOTHER COLD DAY TOMORROW WITH HIGHS STILL STRUGGLING TO
RISE OUT OF THE SINGLE DIGITS. LAKE SNOW WILL WAIN IN THE NORTH
WITH INCREASING INVERSION HEIGHTS AND DRY AIR ADVECTING INTO THE
REGION.
LONG TERM...SUNDAY NIGHT THROUGH SATURDAY.
PRIMARY FOCUS ON LARGE INCREASE IN POPS MONDAY NIGHT/TUE AS
NAM/GFS CONSISTENT ON BREAKAWAY JAMES BAY TROF /FROM BRITISH
COLUMBIA CUTOFF/ AIDING PLAINS CYCLOGENESIS DY2. FAVOR SLIGHTLY
GFS FASTER/FURTHER SOUTH SOLN GIVEN ARCTIC HIGH PUSH INTO WRN
TN/FAR SOUTH INITIAL BAROCLINIC ZONE. BEST 7H HGT FALLS WELL NORTH
THROUGH CENTRAL MICHIGAN WITH TONGUE OF 2-2.5 G/KG 1000-850 MB
MIXING RATIOS ADVECTING NORTHEAST AHEAD OF FNT WITH NEAR 3 G/KG
FAR SRN CWA. RAISED POPS SUBSTANTIALLY TO CATEGORICAL MONDAY NIGHT
FAR NORTH WHERE BEST DYNAMICS LIFT/DGZ THERMALS EXIST AND LIKELY
POPS SOUTH IN RICHER LLVL MOISTURE. FEW CHNGS LTR PDS.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WIND CHILL ADVISORY UNTIL 10 AM EST /9 AM CST/ THIS MORNING FOR
     INZ003>009-012>018-020-022>027-032>034.
MI...WIND CHILL ADVISORY UNTIL 10 AM EST THIS MORNING FOR MIZ077>081.
OH...WIND CHILL ADVISORY UNTIL 10 AM EST THIS MORNING FOR OHZ001-002-
     004-005-015-016-024-025.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR LMZ043-046.
     FREEZING SPRAY ADVISORY UNTIL 5 AM EST EARLY THIS MORNING FOR
     LMZ043-046.
&&
$$
SHORT TERM...CHAMBERLAIN
LONG TERM...MURPHY
AVIATION...LOTHAMER
UPDATE...SCHOTT
</pre> in
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
808 PM EST SAT JAN 19 2008
.EVENING UPDATE...
HAVE MADE SOME SIGNIFICANT CHANGES THIS PERIOD...WITH REPORTS FROM
OBSERVERS ACROSS THE PREFERRED LAKE EFFECT REGION IT IS FAIRLY
OBVIOUS THAT WE ARE FALLING SHORT OF THE CRITERIA FOR THE LAKE
EFFECT ADVISORY. HAVE ENDED IT...AND EXTENDED THE WIND CHILL
ADVISORY FOR THE OVERNIGHT HOURS INTO THOSE COUNTIES. HAVE
SLIGHTLY LOWERED TEMPS SOME. OMEGAS CONTINUE THROUGH THE NIGHT OFF
THE LAKE...BUT THE VERY DRY ARCTIC AIR HAS LIMITED THE MOISTURE
AND THE AMOUNTS. THOUGH LIGHT SNOW WILL CONTINUE ACROSS THE
NORTHWESTERN PORTIONS OF THE AREA...AMOUNTS WILL BE WELL LESS THAN
3 INCHES IN THE NEXT 12 HOURS...AND THEREFORE ALLOWING THE
CANCELING OF THE ADVISORY. ROADS WILL STILL BE DIFFICULT TO TRAVEL
IN SPOTS WITH THE SNOWFALL...BUT THE SNOW SHOULD BE FAIRLY POWDERY
AND BLOWING AND DRIFTING SOME WITH THE 10-15KT WINDS LIKELY THRU
MUCH OF THE NIGHT.
&&
.PREV DISCUSSION... /ISSUED 621 PM EST SAT JAN 19 2008/
AVIATION (00Z TAFS)...
THE MAJORITY OF THE REGION WILL REMAIN UNDER VFR CONDITIONS...AREAS
AROUND LAKE MICHIGAN TOWARDS NORTHWEST OHIO WILL SEE OCCASIONAL
LIGHT SNOW SHOWERS THAT MAY DROP VSBYS TO AROUND 1 TO 2 SM AND
MARGINAL MVFR CIGS AROUND 2.5 K FT. WESTERLY WINDS WILL CONTINUE
THRU THE PERIOD. THE LAKE EFFECT CLOUDS AND SNOW WILL LESSEN
OVERNIGHT INTO SUNDAY MORNING WITH THE ENTIRE AREA BECOMING VFR BY
AFTERNOON.
PREV DISCUSSION... /ISSUED 459 PM EST SAT JAN 19 2008/
SHORT TERM...
.ARCTIC HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE REGION...
COLD ARCTIC AIR IN PLACE WILL CONTINUE TO SUPPORT LAKE EFFECT SNOW
SHOWERS TONIGHT. SATELLITE/RADAR/AND SFC OBS CONFIRM LAKE SNOWS
CONTINUING ACROSS PORTIONS OF NORTHERN IN AND SOUTHERN MI. FARTHER
AWAY FROM THE LAKE...LAKE MODIFIED AIRMASS IN PLACE HAS SUPPORTED
THE DEVELOPMENT OF DIURNAL CU AND LIGHT SNOW FROM AREAS EAST OF A
WARSAW-HILLSDALE LINE. FORECAST MODELS HAVE A GOOD HANDLE OF THE AIR
MASS IN PLACE...WITH THE GFS DISPLAYING A SLIGHTLY BETTER HANDLE OF
BAROCLINIC ZONES AND H925 TEMPS. HAVE TAILORED THE SHORT TERM
PACKAGE MAINLY TO GFS AND RUC 13.
TONIGHT...WEAK SHORTWAVE TROUGH OVER PORTIONS OF IA WILL SWING INTO
THE REGION AND FORCING WEAK LARGE SCALE ASCENT...SUPPORTING A BRIEF
RAISE IN INVERSION HEIGHTS OVER THE LAKE. THIS COMBINED WITH
ONGOING CAA WILL SUPPORT LAKE INDUCED CAPES OF AROUND 400
J/KG...MAINLY THIS EVENING AND EARLY MORNING...BEFORE INVERSION
HEIGHTS RAPIDLY FALL AND SUBSTANTIALLY DRY AIR ADVECTS INTO THE
REGION AROUND H925-H850. GIVEN DRY AIR IN PLACE...EXTREMELY COLD
AIRMASS WITH SMALL CRYSTAL FORMATION FAVORED...AND 290 DEGREE
FETCH...EXPECTING SNOW ACCUMS TO BE ON THE LIGHT SIDE OF 1-3 INCHES
WITH LOCALLY HEAVIER AMOUNTS UP TO 4 INCHES INTO SUNDAY MORNING.
HAVE ALLOWED THE WINTER WEATHER ADVISORY TO CONTINUE GIVEN SNOW
ACCUMS...BRISK WINDS OF 15 TO 25 CREATING DANGEROUS WIND CHILLS OF
15 TO 20 BELOW...AND BLOWING/DRIFTING SNOW POTENTIAL.
ELSEWHERE AWAY FROM THE LAKE...EXPECT A BITTER COLD NIGHT WITH
MOSTLY CLEAR SKIES AND COLD TEMPS. EXPECTED LOWS OF ZERO TO 5 BELOW
AND WINDS OF 15 TO 25 MPH WILL SUPPORT DANGEROUS WIND CHILLS OF 15
TO 25 BELOW ZERO.
LOOK FOR ANOTHER COLD DAY TOMORROW WITH HIGHS STILL STRUGGLING TO
RISE OUT OF THE SINGLE DIGITS. LAKE SNOW WILL WAIN IN THE NORTH
WITH INCREASING INVERSION HEIGHTS AND DRY AIR ADVECTING INTO THE
REGION.
LONG TERM...
SUNDAY NIGHT THROUGH SATURDAY. PRIMARY FOCUS ON LARGE INCREASE IN
POPS MONDAY NIGHT/TUE AS NAM/GFS CONSISTENT ON BREAKAWAY JAMES BAY
TROF /FROM BRITISH COLUMBIA CUTOFF/ AIDING PLAINS CYCLOGENESIS DY2.
FAVOR SLIGHTLY GFS FASTER/FURTHER SOUTH SOLN GIVEN ARCTIC HIGH PUSH
INTO WRN TN/FAR SOUTH INITIAL BAROCLINIC ZONE. BEST 7H HGT FALLS
WELL NORTH THROUGH CENTRAL MICHIGAN WITH TONGUE OF 2-2.5 G/KG
1000-850 MB MIXING RATIOS ADVECTING NORTHEAST AHEAD OF FNT WITH
NEAR 3 G/KG FAR SRN CWA. RAISED POPS SUBSTANTIALLY TO CATEGORICAL
MONDAY NIGHT FAR NORTH WHERE BEST DYNAMICS LIFT/DGZ THERMALS EXIST
AND LIKELY POPS SOUTH IN RICHER LLVL MOISTURE. FEW CHNGS LTR PDS.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WIND CHILL ADVISORY UNTIL 10 AM EST /9 AM CST/ SUNDAY FOR
     INZ003>009-012>018-020-022>027-032>034.
MI...WIND CHILL ADVISORY UNTIL 10 AM EST SUNDAY FOR MIZ077>081.
OH...WIND CHILL ADVISORY UNTIL 10 AM EST SUNDAY FOR OHZ001-002-004-
     005-015-016-024-025.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM EST SUNDAY FOR LMZ043-046.
     FREEZING SPRAY ADVISORY UNTIL 5 AM EST SUNDAY FOR LMZ043-046.
&&
$$
SHORT TERM...CHAMBERLAIN
LONG TERM...MURPHY
UPDATE...SCHOTT
</pre> in
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
621 PM EST SAT JAN 19 2008
.AVIATION (00Z TAFS)...
THE MAJORITY OF THE REGION WILL REMAIN UNDER VFR CONDITIONS...AREAS
AROUND LAKE MICHIGAN TOWARDS NORTHWEST OHIO WILL SEE OCCASIONAL
LIGHT SNOW SHOWERS THAT MAY DROP VSBYS TO AROUND 1 TO 2 SM AND
MARGINAL MVFR CIGS AROUND 2.5 K FT. WESTERLY WINDS WILL CONTINUE
THRU THE PERIOD. THE LAKE EFFECT CLOUDS AND SNOW WILL LESSEN
OVERNIGHT INTO SUNDAY MORNING WITH THE ENTIRE AREA BECOMING VFR BY
AFTERNOON.
&&
.PREV DISCUSSION... /ISSUED 459 PM EST SAT JAN 19 2008/
SHORT TERM...
..ARCTIC HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE REGION...
COLD ARCTIC AIR IN PLACE WILL CONTINUE TO SUPPORT LAKE EFFECT SNOW
SHOWERS TONIGHT. SATELLITE/RADAR/AND SFC OBS CONFIRM LAKE SNOWS
CONTINUING ACROSS PORTIONS OF NORTHERN IN AND SOUTHERN MI. FARTHER
AWAY FROM THE LAKE...LAKE MODIFIED AIRMASS IN PLACE HAS SUPPORTED
THE DEVELOPMENT OF DIURNAL CU AND LIGHT SNOW FROM AREAS EAST OF A
WARSAW-HILLSDALE LINE. FORECAST MODELS HAVE A GOOD HANDLE OF THE AIR
MASS IN PLACE...WITH THE GFS DISPLAYING A SLIGHTLY BETTER HANDLE OF
BAROCLINIC ZONES AND H925 TEMPS. HAVE TAILORED THE SHORT TERM
PACKAGE MAINLY TO GFS AND RUC 13.
TONIGHT...WEAK SHORTWAVE TROUGH OVER PORTIONS OF IA WILL SWING INTO
THE REGION AND FORCING WEAK LARGE SCALE ASCENT...SUPPORTING A BRIEF
RAISE IN INVERSION HEIGHTS OVER THE LAKE. THIS COMBINED WITH
ONGOING CAA WILL SUPPORT LAKE INDUCED CAPES OF AROUND 400
J/KG...MAINLY THIS EVENING AND EARLY MORNING...BEFORE INVERSION
HEIGHTS RAPIDLY FALL AND SUBSTANTIALLY DRY AIR ADVECTS INTO THE
REGION AROUND H925-H850. GIVEN DRY AIR IN PLACE...EXTREMELY COLD
AIRMASS WITH SMALL CRYSTAL FORMATION FAVORED...AND 290 DEGREE
FETCH...EXPECTING SNOW ACCUMS TO BE ON THE LIGHT SIDE OF 1-3 INCHES
WITH LOCALLY HEAVIER AMOUNTS UP TO 4 INCHES INTO SUNDAY MORNING.
HAVE ALLOWED THE WINTER WEATHER ADVISORY TO CONTINUE GIVEN SNOW
ACCUMS...BRISK WINDS OF 15 TO 25 CREATING DANGEROUS WIND CHILLS OF
15 TO 20 BELOW...AND BLOWING/DRIFTING SNOW POTENTIAL.
ELSEWHERE AWAY FROM THE LAKE...EXPECT A BITTER COLD NIGHT WITH
MOSTLY CLEAR SKIES AND COLD TEMPS. EXPECTED LOWS OF ZERO TO 5 BELOW
AND WINDS OF 15 TO 25 MPH WILL SUPPORT DANGEROUS WIND CHILLS OF 15
TO 25 BELOW ZERO.
LOOK FOR ANOTHER COLD DAY TOMORROW WITH HIGHS STILL STRUGGLING TO
RISE OUT OF THE SINGLE DIGITS. LAKE SNOW WILL WAIN IN THE NORTH
WITH INCREASING INVERSION HEIGHTS AND DRY AIR ADVECTING INTO THE
REGION.
LONG TERM...
SUNDAY NIGHT THROUGH SATURDAY. PRIMARY FOCUS ON LARGE INCREASE IN
POPS MONDAY NIGHT/TUE AS NAM/GFS CONSISTENT ON BREAKAWAY JAMES BAY
TROF /FROM BRITISH COLUMBIA CUTOFF/ AIDING PLAINS CYCLOGENESIS DY2.
FAVOR SLIGHTLY GFS FASTER/FURTHER SOUTH SOLN GIVEN ARCTIC HIGH PUSH
INTO WRN TN/FAR SOUTH INITIAL BAROCLINIC ZONE. BEST 7H HGT FALLS
WELL NORTH THROUGH CENTRAL MICHIGAN WITH TONGUE OF 2-2.5 G/KG
1000-850 MB MIXING RATIOS ADVECTING NORTHEAST AHEAD OF FNT WITH
NEAR 3 G/KG FAR SRN CWA. RAISED POPS SUBSTANTIALLY TO CATEGORICAL
MONDAY NIGHT FAR NORTH WHERE BEST DYNAMICS LIFT/DGZ THERMALS EXIST
AND LIKELY POPS SOUTH IN RICHER LLVL MOISTURE. FEW CHNGS LTR PDS.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WIND CHILL ADVISORY UNTIL 10 AM EST /9 AM CST/ SUNDAY FOR
     INZ003>009-012>018-020-022>027-032>034.
MI...WIND CHILL ADVISORY UNTIL 10 AM EST SUNDAY FOR MIZ080-081.
     WINTER WEATHER ADVISORY UNTIL 10 AM EST SUNDAY FOR MIZ077>079.
OH...WIND CHILL ADVISORY UNTIL 10 AM EST SUNDAY FOR OHZ001-002-004-
     005-015-016-024-025.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM EST SUNDAY FOR LMZ043-046.
     FREEZING SPRAY ADVISORY UNTIL 5 AM EST SUNDAY FOR LMZ043-046.
&&
$$
SHORT TERM...CHAMBERLAIN
LONG TERM...MURPHY
AVIATION...SCHOTT
</pre> in
AREA FORECAST DISCUSSION...DELAYED
NATIONAL WEATHER SERVICE NORTHERN INDIANA
459 PM EST SAT JAN 19 2008
.SHORT TERM...
...ARCTIC HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE REGION...
COLD ARCTIC AIR IN PLACE WILL CONTINUE TO SUPPORT LAKE EFFECT SNOW
SHOWERS TONIGHT. SATELLITE/RADAR/AND SFC OBS CONFIRM LAKE SNOWS
CONTINUING ACROSS PORTIONS OF NORTHERN IN AND SOUTHERN MI. FARTHER
AWAY FROM THE LAKE...LAKE MODIFIED AIRMASS IN PLACE HAS SUPPORTED
THE DEVELOPMENT OF DIURNAL CU AND LIGHT SNOW FROM AREAS EAST OF A
WARSAW-HILLSDALE LINE. FORECAST MODELS HAVE A GOOD HANDLE OF THE AIR
MASS IN PLACE...WITH THE GFS DISPLAYING A SLIGHTLY BETTER HANDLE OF
BAROCLINIC ZONES AND H925 TEMPS. HAVE TAILORED THE SHORT TERM
PACKAGE MAINLY TO GFS AND RUC 13.
TONIGHT...WEAK SHORTWAVE TROUGH OVER PORTIONS OF IA WILL SWING INTO
THE REGION AND FORCING WEAK LARGE SCALE ASCENT...SUPPORTING A BRIEF
RAISE IN INVERSION HEIGHTS OVER THE LAKE. THIS COMBINED WITH
ONGOING CAA WILL SUPPORT LAKE INDUCED CAPES OF AROUND 400
J/KG...MAINLY THIS EVENING AND EARLY MORNING...BEFORE INVERSION
HEIGHTS RAPIDLY FALL AND SUBSTANTIALY DRY AIR ADVECTS INTO THE
REGION AROUND H925-H850. GIVEN DRY AIR IN PLACE...EXTREMELY COLD
AIRMASS WITH SMALL CRYSTAL FORMATION FAVORED...AND 290 DEGREE
FETCH...EXPECTING SNOW ACCUMS TO BE ON THE LIGHT SIDE OF 1-3 INCHES
WITH LOCALLY HEAVIER AMOUNTS UP TO 4 INCHES INTO SUNDAY MORNING.
HAVE ALLOWED THE WINTER WEATHER ADVISORY TO CONTINUE GIVEN SNOW
ACCUMS...BRISK WINDS OF 15 TO 25 CREATING DANGEROUS WIND CHILLS OF
15 TO 20 BELOW...AND BLOWING/DRIFTING SNOW POTENTIAL.
ELSEWHERE AWAY FROM THE LAKE...EXPECT A BITTER COLD NIGHT WITH
MOSTLY CLEAR SKIES AND COLD TEMPS. EXPECTED LOWS OF ZERO TO 5 BELOW
AND WINDS OF 15 TO 25 MPH WILL SUPPORT DANGEROUS WIND CHILLS OF 15
TO 25 BELOW ZERO.
LOOK FOR ANOTHER COLD DAY TOMORROW WITH HIGHS STILL STRUGGLING TO
RISE OUT OF THE SINGLE DIGITS. LAKE SNOW WILL WAIN IN THE NORTH
WITH INCREASING INVERSION HEIGHTS AND DRY AIR ADVECTING INTO THE
REGION.
&&
.LONG TERM...
SUNDAY NIGHT THROUGH SATURDAY. PRIMARY FOCUS ON LARGE INCREASE IN
POPS MONDAY NIGHT/TUE AS NAM/GFS CONSISTENT ON BREAKAWAY JAMES BAY
TROF /FROM BRITISH COLUMBIA CUTOFF/ AIDING PLAINS CYCLOGENISIS DY2.
FAVOR SLIGHTLY GFS FASTER/FURTHER SOUTH SOLN GIVEN ARCTIC HIGH PUSH
INTO WRN TN/FAR SOUTH INITIAL BAROCLINIC ZONE. BEST 7H HGT FALLS
WELL NORTH THROUGH CENTRAL MICHIGAN WITH TONGUE OF 2-2.5 G/KG
1000-850 MB MIXING RATIOS ADVECTING NORTHEAST AHEAD OF FNT WITH
NEAR 3 G/KG FAR SRN CWA. RAISED POPS SUBSTANTIALLY TO CATEGORICAL
MONDAY NIGHT FAR NORTH WHERE BEST DYNAMICS LIFT/DGZ THERMALS EXIST
AND LIKELY POPS SOUTH IN RICHER LLVL MOISTURE. FEW CHNGS LTR PDS.
&&
.AVIATION.../18Z TAFS/
COLD ARCTIC HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE REGION
TODAY...SUPPORTING LAKE SNOWS OVER NORTHERN PORTIONS OF THE FA.
LOOK FOR CIGS DOWN TO 2 KFT IN THIS AREA INCLUDING AREAS NORTH OF
A LINE FROM MCY TO FWA...AS LAKE MOISTURE MIXES WITH DAYTIME
HEATING. A WEAK SHORTWAVE WILL PUSH INTO THE REGION THIS EVENING
HELPING TO INCREASE LAKE SNOW INTENSITY SOME...VISIBILITIES MAY
DROP TO 3/4SM OVER SOUTHERN LOWER MI AND EXTREME NORTHERN INDIANA
THROUGH MUCH OF THE EVENING. EXPECTING DIURNAL CU TO DISSIPATE
WITH SUNSET OVER EASTERN PORTIONS OF THE FA. OTHERWISE...GUSTY NW
WINDS ARE EXPECTED THROUGH THE PERIOD. EXPECTING WINDS OF 10 T0 20
KNOTS WITH GUSTS UP TO 25 THIS EVENING. LOOK FOR A DECREASE IN
LAKE SNOW INTENSITY AND A SHIFT NORTH THROUGH SUNDAY AS HIGH
PRESSURE BRINGS LOWERING INVERSION HEIGHTS AND MICH DRIER AIR INTO
THE REGION.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WIND CHILL ADVISORY UNTIL 10 AM EST /9 AM CST/ SUNDAY FOR
     INZ003>009-012>018-020-022>027-032>034.
MI...WIND CHILL ADVISORY UNTIL 10 AM EST SUNDAY FOR MIZ080-081.
     WINTER WEATHER ADVISORY UNTIL 10 AM EST SUNDAY FOR MIZ077>079.
OH...WIND CHILL ADVISORY UNTIL 10 AM EST SUNDAY FOR OHZ001-002-004-
     005-015-016-024-025.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM EST SUNDAY FOR LMZ043-046.
     FREEZING SPRAY ADVISORY UNTIL 5 AM EST SUNDAY FOR LMZ043-046.
&&
$$
SHORT TERM...CHAMBERLAIN
LONG TERM...MURPHY
AVIATION...CHAMBERLAIN
</pre> in
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
111 AM EST SAT JAN 19 2008
.AVIATION...
THE SYNOPTIC SNOW IS EXPECTED TO END SOON AT FWA AND SOME LAKE
EFFECT SNOW IS HEADING THAT WAY...AFFECTING THE AIRPORT OFF AND
ON. OBS AT FWA WENT TO VFR BUT THE SNOW COULD BRING CONDITIONS
DOWN TO MVFR WHILE THE SNOW IS FALLING. QUESTION YET REMAINS FOR
FWA LATER TODAY ON HOW MUCH OF THE LOWER...MVFR...LAKE EFFECT
CLOUDS WILL PASS THROUGH FWA. AT THIS POINT WILL STAY WITH THE
FORECAST BUT THIS WILL HAVE TO BE WATCHED. LAKE EFFECT SNOW IS
MOVING THROUGH SBN BUT THE SNOW IS NOT DROPPING THE VISIBILITY. SO
WILL CONTINUE WITH THE MVFR CEILINGS AND WILL HAVE TO WATCH TO SEE
IF ANY HEAVIER BANDS WILL SET UP AND MOVE TOWARDS SBN. AT TAF
ISSUANCE TIME THE WIND AT FWA WAS STILL SOUTHWESTERLY BUT WILL BE
MOVING TO THE NORTHWEST AS THAT FRONT SOON MOVES THROUGH. THE
WIND IS GOING TO STAY STRONG AND GUSTY OUT OF THE NORTHWEST
THROUGH TODAY.
&&
.UPDATE... /ISSUED 929 PM EST FRI JAN 18 2008/
QUICK UPDATE TO ADJUST THE POPS FOR THE FASTER TIMING OF THE
PRECIP WITH THE ARCTIC FRONT MOVING ACROSS THE REGION. A QUICK .5
TO 1 INCH OF SNOW WILL BE POSSIBLE AS THE LINE MOVES ACROSS THE
EASTERN HALF OF THE FORECAST AREA. MADE SOME MINOR ADJUSTMENTS TO
TEMPS IN THE NEXT 12 HOURS WITH AN ADJUSTMENT TOWARDS THE LATEST
RUC DATA.
&&
.PREV DISCUSSION... /ISSUED 359 PM EST FRI JAN 18 2008/
SHORT TERM...TONIGHT THROUGH SUNDAY.
NUMEROUS HAZARDS IN NEAR TERM. 13C/12HR TEMP FALL AT 8H/KABR WITH
PASSAGE ARCTIC FROPA...SFC FRONT NOW POISED JUST NW OF CWA AT 20
UTC INTO NRN IL WITH STRONG ISALLOBARIC COUPLET/FNTL WAVE NEAR
KSTL AIDING EXPANSION OF LRG AREA LIGHT SN. FURTHER MOISTURE
FLUX/LAKE ENHANCEMENT TO PROVIDE HEAVIEST SNOW IMMEDIATELY
DOWNWIND OF LK MI WHERE FNTL LIFT/DGZ/SATURATION ARE COLLOCATED.
FURTHER DOWNSTREAM SATURATION LAGS HOURS BEHIND INTO COLDER
AIRMASS...WHEN LES PROCESSES WILL TEND TO BECOME OVERALL DOMINANT.
MINOR CHANGES WRT LES EVENT...ADDED ST. JOSEPH MI TO WINTER
WEATHER ADVISORY AND EXTENDED ADVISORY INTO SUNDAY MORNING WITH
MOISTURE DEPTH WRT ICE REMAINING AOA 4KFT UNTIL 15 UTC SUNDAY
BEFORE STEERING FLOW BACKS AHEAD OF NEXT. DRAWN OUT SNOW
ACCUMS/EACH PERIOD SUB ADVISORY CRITERIA/FOR SWRN 3 MI COUNTIES
PRIMARY WINTER WX HAZARD WITH SECONDARY MINOR BLSN/WIND CHILL
ADDING TO OVERALL PROLONGED WINTER WX HAZARD. PSBLY BEST POTENTIAL
MAY BE SATURDAY NIGHT WITH RAISED DEPTH OF MOISTURE/SLIGHT
SHORTWAVE PASSAGE RAISING MIXED HEIGHT WITH LAKE INDUCED CAPE OF
500-600 J/KG AND LK INDUCED EQL TO 9000 FEET. ELSEWHERE...WIND
CHILL ADVISORY CRITERIA TO BE MET SATURDAY NIGHT TIMEFRAME...FIRST
IN SWRN ZONES WHERE LACK OF LES CLOUDS/LIGHT FRESH SNOW ACCUMS
FURTHER AIDING RADIATIONAL COOLING TO TAKE SFC TEMPS WELL BLO
FREEZING...CONTD PREV FCST OF ABOUT M5F...WITH LOWEST APPARENT T
OF M20-M23F SATURDAY NIGHT. COORDINATED MARINE NEARSHORE FREEZING
SPRAY ADVISORY WITH KGRR WITH 11 AM ISSUANCE...20 TO 25 KNOTS AND
GIVEN AIR TEMPS OVER WATER ANTICIPATE MODERATE ICE ACCRUAL TONIGHT
INTO AT LEAST SATURDAY. OUTSIDE OF LAKE EFFECT AREA...HIGH
PROBABILITY ACCUM TONIGHT...THOUGH GENERALLY AN INCH OR
LESS...THEN OPTED FOR SCATTERED WORDING VS CHC IN LOW POP LES
AREAS FOR SAT/SAT NIGHT. MORE FLURRIES SOUTH OF ROUTE 6 IN NRN
IN/NRN OH SAT NIGHT AS IN CLOUD FLOW BACKS SLIGHTLY TO ABOUT
275-280...FAVORING MI AND PERHAPS BORDER CITIES IN ST. JOE/ELKHART
COUNTIES.
LONG TERM...SUNDAY NIGHT THROUGH FRIDAY.
THE MAIN CHALLENGES OF THIS PERIOD CENTER ON THE DEVELOPMENT AND
PROGRESSION OF THE LONG WAVE TROF ALONG THE WEST CONUS. THE 12Z
ECMWF AND GFS OPERATIONAL RUNS BOTH SHEAR OUT AN UPPER
TROF...HELPING A CUT OFF LOW TO FORM OVER CALIFORNIA BY TUESDAY.
THIS LOW WILL ATTEMPT TO BECOME PHASED WITH THE MAIN UPPER FLOW AS
SEVERAL SUBSEQUENT STRONG UPPER TROFS ALSO ATTEMPT TO DROP SOUTH
INTO THE CONUS. THIS SCENARIO WILL EVENTUALLY PROVIDE A WIDE ARRAY
OF UPPER AIR SOLUTIONS AS THESE SMALLER TROFS MOVE ACROSS WESTERN
CANADA TOWARD THE CONUS. FSU/UCAR EXPERIMENTAL GRAPHICS INDICATE
AVERAGE CONFIDENCE WITH THE PAST 5 GFS RUNS...BUT MOST OF THESE
PAST RUNS HAVE SHOWN SIGNIFICANT UNCERTAINTY PAST TUESDAY. SO ALL
THESE THINGS CONSIDERED...KEPT A CHANCE FOR SNOW MONDAY INTO
TUESDAY WITH THE ARRIVAL OF THE FIRST SHORT WAVE. AFTER
TUESDAY...KEPT TEMPERATURES WELL BELOW NORMAL...AND CLOSER TO THE
00Z MEX. LAKE EFFECT SNOW SHOWER CHANCES WILL NEED SOME FINE
TUNING DOWN THE ROAD...BUT FOR NOW HAVE A CHANCE FOR SNOW OR LAKE
EFFECT SNOW UNTIL FRIDAY. KEPT TEMPERATURES WELL BELOW NORMAL.
STILL MUCH QUESTION IF ANOTHER STRONG ARCTIC FRONT WILL BE ABLE TO
REACH THE AREA THURSDAY OR FRIDAY. FOR NOW...KEPT TEMPERATURES
COLD HERE IN LIGHT OF EARLIER GFS RUNS.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WIND CHILL ADVISORY FROM 7 PM EST /6 PM CST/ THIS EVENING TO 10
     AM EST /9 AM CST/ SUNDAY FOR INZ003>009-012>018-020-022>027-
     032>034.
MI...WIND CHILL ADVISORY FROM 7 PM THIS EVENING TO 10 AM EST SUNDAY
     FOR MIZ080-081.
     WINTER WEATHER ADVISORY UNTIL 10 AM EST SUNDAY FOR MIZ077>079.
OH...WIND CHILL ADVISORY FROM 7 PM THIS EVENING TO 10 AM EST SUNDAY
     FOR OHZ001-002-004-005-015-016-024-025.
LM...SMALL CRAFT ADVISORY UNTIL 7 AM EST SUNDAY FOR LMZ043-046.
     FREEZING SPRAY ADVISORY UNTIL 7 PM EST THIS EVENING FOR LMZ043-
     046.
&&
$$
SHORT TERM...MURPHY
LONG TERM...SKIPPER
AVIATION...LOTHAMER
UPDATE...SCHOTT
</pre> in
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DODGE CITY KS
252 PM CST SUN JAN 20 2008
.DISCUSSION...
DAYS 1-2...
MAIN FORECAST HEADACHE WILL BE THE ARCTIC FRONT COMING DOWN
TONIGHT AND TOMORROW, AND IF WE GET ANY PRECIP WITH IT.
WV LOOP SHOWS TROUGH DIGGING INTO THE WESTERN CONUS, WITH THE 12Z
UPPER AIR MAPS INDICATING 170 M HEIGHT FALLS ASSOCIATED WITH IT.
850MB TEMPS AT 12Z WERE A BIT WARMER THAN YESTERDAY, WITH A POCKET
OF ABOVE ZERO C EVIDENT OVER THE WESTERN PLAINS. THE COLD AIR WAS
NOT FAR BEHIND HOWEVER, WITH THE TEENS BELOW ZERO TO -20 C OVER
MT BEHIND THE ARCTIC FRONT. AT THE SFC, WARM AIR HAS PUSHED
NORTHWARD ACROSS MUCH OF THE CWA, WITH TEMPERATURES GETTING INTO
THE 40S, WHILE THE TEENS REMAIN OVER NEB. MODELS ARE ALL IN PRETTY
GOOD AGREEMENT ON THE TEMPERATURE GRADIENT TIGHTENING OVERNIGHT AS
THE UPPER TROUGH CONTINUES TO DIG AND THE SFC LOW GETS CENTERED
NEAR EHA. THE GFS, NAM, AND UKMET ARE ALL IN PRETTY GOOD AGREEMENT
ON BRINGING THE COLD FRONT DOWN A BIT SLOWER THAN YESTERDAY`S
RUNS, PUTTING THE BOUNDARY NEAR THE CENTRAL CWA AT 12Z. THE RUC
AND SREF MEAN ARE EVEN SLOWER THAN THIS SOLUTION. ARCTIC AIR
OFTEN COMES DOWN FASTER THAN EXPECTED, BUT THE BOUNDARY HAS STAYED
FAIRLY STATIONARY OVER FAR NORTHERN KS THROUGHOUT THE DAY TODAY.
WILL LEAN MORE TOWARDS THE NAM/GFS FOR NOW. THUS, BUMPED UP
OVERNIGHT LOWS A BIT OVER OUR SOUTHERN AND CENTRAL COUNTIES INTO
THE 20S. ALSO BUMPED UP HIGHS IN OUR SOUTHEAST FOR TOMORROW,
ALTHOUGH FULLY EXPECT THERE WILL BE A NON-DIURNAL TEMPERATURE
PATTERN FOR MOST OF THE CWA, WITH FALLING TEMPS AFTER THE FRONT COMES
THROUGH.
THE COLD FRONT SHOULD MOVE THE REST OF THE WAY THROUGH THE CWA BY
LATE MONDAY AFTERNOON. MODEL SOUNDINGS CONTINUE TO SHOW A FAIRLY
SHALLOW MOIST LAYER BELOW 700MB. GFS AND NAM SHOW SOME DECENT
ISENTROPIC LIFT AT 285 K OVER OUR SOUTHEASTERN CORNER BY MONDAY
EVENING. THINK THIS AREA AS WELL AS THE FAR NORTH WILL SEE THE
BEST, IF FAIRLY MINOR, SHOT AT GETTING ANYTHING MEASURABLE. THUS,
ADJUSTED GRIDS TO REFLECT THE SLIGHTLY HIGHER POPS IN THAT AREA.
STILL, WITH THE SHALLOW MOISTURE DON`T EXPECT TO SEE MUCH. WITH
THE DRY MID-LEVELS, THINK THAT FZDL LOOKS MOST LIKELY TYPE,
ALTHOUGH WE COULD GET SOME SNOWFLAKES MIXING IN AS THE TEMPS GET
CLOSER TO -10 C. ANY PRECIP SHOULD TAPER OFF MONDAY EVENING AS THE
FLOW SPLITS AND THE NORTHERN BRANCH SHORTWAVE DIGS INTO THE
CENTRAL PLAINS, DRIVING THE HIGH PRESSURE CENTER SOUTH.
CONDITIONS SHOULD BE QUIET PRECIP-WISE BY TUESDAY, ALTHOUGH COLD.
THINK THAT CLOUDS SHOULD BEGIN TO BREAK UP AFTER MIDNIGHT MONDAY
NIGHT, AND WITH ARCTIC AIR IN PLACE TEMPS SHOULD DROP LIKE A ROCK.
HYS, WHICH STILL HAS SNOWCOVER, COULD EVEN SEE LOWS DIP BELOW ZERO
F. CONTINUED WITH LOWS IN THE SINGLE DIGITS ELSEWHERE IN THE AREA.
THE SFC HIGH WILL REMAIN IN PLACE TUESDAY AS THE UPPER FLOW
BECOMES MORE NORTHWESTERLY. WITH 850MB TEMPS BELOW -10 C, HIGHS
WILL NOT GET VERY FAR EVEN WITH SUNSHINE, STAYING MOSTLY IN THE
20S.
DAYS 3-7...
NO MAJOR CHANGES PLANNED TO THE LATER PERIODS. WILL HOWEVER BE
INTERESTING IN HOW MUCH OF A WARM UP THAT WILL OCCUR LATE WEEK AS A
S/W RIDGE BUILDS INTO THE AREA.
MODELS AND ENSEMBLES TODAY CONTINUE TO HINT AT A
RETROGRADING/REDEVELOPING RIDGE FROM ROUGHLY 140W TO 160W LATE WEEK.
THIS WILL ALLOW FOR AN UPPER LOW TO REMAIN FIRMLY ANCHORED OVER THE
SW CONUS. S/W RIDGE BUILDING INTO THE AREA TOWARDS THE WEEKEND
SHOULD ENHANCE LEE SIDE TROFING FROM THE WESTERLY DOWNSLOPE FLOW
ALONG WITH INCREASING WINDS AND WARMER TEMPS. HAVE THEREFORE BUMPED
TEMPS UP A FEW MORE DEGREES BY THE WEEKEND PERIOD. MAY EVEN NEED TO
BE BUMPED UP SOME MORE IF THIS TREND VERIFIES.
-BURGERT
.AVIATION...
THROUGH THE FIRST HALF OF THE NIGHT WILL HAVE ONLY CI TO CONTEND
WITH ACROSS SOUTHWEST KANSAS. AFTER 9Z HOWEVER THINGS WILL CHANGE. A
STRONG COLD FRONT WILL CROSS AREA AND AS IT DOES WINDS WILL QUICKLY
SHIFT TO THE NORTHWEST AND INCREASE INTO THE 15 TO 25 MPH RANGE.
BOTH NAM/GFS TODAY WERE SLOWER AND SIMILAR IN TIMING OF OUR WIND
SHIFT SO OPTED TO USE THESE MODELS AS A GUIDE FOR TIMING OF FROPA.
BEHIND THIS FRONT SFC-925RH FIELD QUICKLY SATURATE SO HAVE THEREFORE
QUICKLY INTRODUCED LOW CLOUDS  BEHIND THIS FRONT. PCPN STILL LOOKS
LIKE A POSSIBILITY AS LOW CLOUDS RETURN EARLY MONDAY MORNING.
ALTHOUGH THIS IS TOWARDS THE END OF THE TAF PERIOD HAVE DECIDED TO
INCLUDE LIGHT FZDZ OR SN INTO THE TAFS.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC  20  26   3  21 /   0  10  10   0
GCK  17  20   0  23 /  10  20  10   0
EHA  18  25   8  26 /   0  10  10   0
LBL  22  28   5  26 /   0  10  10   0
HYS  11  18  -1  19 /  10  20  10   0
P28  25  38   8  25 /   0  20  20   0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
FN26/18
</pre> ks
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GOODLAND KS
1040 AM MST SAT JAN 19 2008
.AVIATION...
FOR THE 18Z TAF...VFR CONDITIONS WILL PERSIST THROUGH THE TAF
PERIOD. THE SKIES WILL REMAIN SCT-BKN WITH MID-HIGH LEVEL CLOUDS AND
SOUTHWESTERLY WINDS LESS THAN 15 KNOTS.
&&
.PREV DISCUSSION... /ISSUED 232 AM MST SAT JAN 19 2008/
.DISCUSSION...
05Z WATER VAPOR IMAGERY/RUC ANALYSIS INDICATED SHORT WAVE TROUGH
SLIDING ACROSS SOUTHERN COLORADO AROUND BASE OF LONG WAVE TROUGH
ACROSS EASTERN CONUS. LEADING EDGE OF 110KT H3 JET STREAK WAS
BEGINNING TO MOVE ACROSS AREA BEHIND TROUGH. AT THE SFC...1033MB HIGH
WAS DRAPED ACROSS NEBRASKA AND KANSAS...AND SFC TROUGH WAS LOCATED
ACROSS SE CO. OVERALL...BOTH THE NAM AND GFS INITIALIZED RELATIVELY
WELL AT 00Z. ALTHOUGH AT H3 BOTH MODELS SEEMED TO BE TO FAR NORTH
WITH JET MAX BEHIND SE CO TROUGH.
TODAY-TONIGHT...PRECIPITATION CHANCES...IF ANY THROUGH THE MORNING HOURS
WILL BE THE FIRST PROBLEM TO DEAL WITH TODAY. PREVIOUSLY MENTIONED
SHORT WAVE TROUGH WILL BE TO THE SOUTH OF THE WEST OF THE AREA BY
12Z TODAY AND ANY LINGERING PRECIPITATION WITH THAT WILL BE WELL
AWAY FROM THE AREA...HOWEVER 110KT JET STREAK LEFT ENTRANCE REGION
WILL BE OVER THE AREA. AS TROUGH SHIFTS EAST...DEEP WARM AIR
ADVECTION WILL ALSO BE TAKING PLACE AS RIDGE BUILDS IN. AS
TEMPERATURES WARM...AREA OF STEEPER LAPSE RATES OBSERVED ON KDNR RAOB
WILL SHIFT WILL ALSO SHIFT TO THE EAST AND NOT REALLY BE LINED UP
THAT GREAT WITH AVAILABLE ISENTROPIC ASCENT. DEEP LAYER DIV Q VECTORS
SUGGEST THAT SUBSIDENCE FROM BUILDING RIDGE WILL GENERALLY BEAT OUT
TEMPERATURE ADVECTION EFFECTS...ALTHOUGH H7-H5 LAYER DOES SUPPORT
SOME FORCING FOR ASCENT ACROSS CENTRAL PARTS OF THE AREA BY AROUND
12Z. CROSS SECTIONS ALSO SHOW FAIRLY DEEP FRONTOGENESIS ALL ALONG
TEMP GRADIENT ACROSS THE AREA WITH POCKET OF POTENTIAL INSTABILITY
JUST ABOVE FRONTAL SURFACE. MAIN QUESTION IS WHETHER OR NOT THIS
LAYER WILL BE SATURATED OR NOT. NAM AND GFS...DESPITE LARGE
DIFFERENCES IN QPF (DRY VS LIGHT) ACTUALLY SEEM TO HAVE VERY SIMILAR
FORCING STABILITY FIELDS WITH BIG DIFFERENCE IN HOW DRY AIRMASS
BELOW FRONTAL SURFACE IS. WITH OBSERVED SOUNDINGS UPSTREAM TENDING
TO SUPPORT DRIER NAM. FOR NOW THINK WILL GO WITH FLURRIES IN THE
MORNING AND ADJUST BASED ON EARLY MORNING TRENDS. RIDGE WILL BEGIN
TO FLATTEN OVERNIGHT WITH PERSISTENT...WEAK...WARM AIR ADVECTION
ACROSS MUCH OF THE AREA ESPECIALLY BETWEEN H7 AND H5. CROSS SECTIONS
ACROSS THE AREA ALONG WITH POINT SOUNDINGS INDICATE AREA WITH WEAK
LIFT ALSO VERY STABLE. ALTHOUGH THERE APPEARS TO BE WEAK LIFT IN A
SATURATED DENDRITIC LAYER ACROSS THE NORTH...THINK WEAK FORCING
AND STABLE AIRMASS WOULD NOT BE ABLE TO PRODUCE ANYTHING STRONG
ENOUGH TO MAKE IT THROUGH VERY DRY LAYER JUST OFF THE SURFACE.
SUNDAY-SUNDAY NIGHT...NEXT SHORT WAVE TROUGH WILL BEGIN TO MOVE INTO
THE WESTERN CONUS THROUGH THE DAY. SFC LOW WILL DEVELOP ACROSS
EASTERN COLORADO IN RESPONSE AND SLOWLY MOVE SOUTH...BRINGING A COLD
FRONT ACROSS THE AREA IN THE PROCESS. SHORT RANGE MODELS ALL BEGIN
TO BREAK OUT LIGHT PRECIP ACROSS THE AREA BEHIND THE FRONT...MAINLY
IN THE EVENING. SOUNDINGS WOULD SUGGEST THAT PRECIPITATION
PROCESSES WILL BE VERY SHALLOW AS ATMOSPHERE WILL BE SATURATED FROM
ONLY H8 AND DOWN. WITH EASTERLY WINDS ENHANCING ANY LARGE SCALE
FORCING ABOVE THE FRONTAL SURFACE THINK THERE WILL BE A CHANCE FOR
SOME VERY LIGHT PRECIP IF BOUNDARY LAYER CAN SATURATE. ALTHOUGH
MODELS SUGGEST THIS WILL HAPPEN...LOOKING AT HOW DRY THE AIR IS TO
THE EAST OF THE CWA CURRENTLY AM WORRIED THAT MODELS MAY BE
OVERDOING AVAILABLE MOISTURE...ESPECIALLY WHEN FLOW BEGINS TO
BECOME NORTHEAST BEHIND THE FRONT. SOUNDINGS ACTUALLY LOOK ALOT LIKE
A DRIZZLE/FREEZING DRIZZLE SOUNDING WITH SHALLOW SATURATED LAYER
CAPPED BY FAIRLY STRONG SHEAR. ATMOSPHERE WILL GRADUALLY COOL BEHIND
THE FRONT...BUT THERE COULD BE A WINDOW OF LIGHT FZDZ BEFORE THINGS
CHANGE OVER TO LIGHT SNOW. OVERNIGHT...DIV Q FIELDS INDICATE LARGE
SCALE FORCING FOR ASCENT BEGIN TO INCREASE ACROSS THE NORTHWEST CWA
AS TROUGH APPROACHES. THIS IS ALSO ACCOMPANIED BY INCREASING
FRONTOGENESIS BETWEEN H7 AND H6. STILL CONCERNED ABOUT PERSISTENT
DRY LVL MAY HINDER PRECIPITATION FORMATION AND KEEP THINGS
SHALLOW...BUT WILL PUT HIGHEST POPS IN THE NORTHWEST TO ACCOUNT FOR
BETTER FORCING. WINDS SHOULD STAY IN THE 10 TO 20 MPH RANGE
OVERNIGHT AS FRONT MOVES THROUGH THE AREA...AND WITH THE EXPECTED
VERY COLD AIR EXPECTED BEHIND THE FRONT THINK WE WILL SEE WIND
CHILLS IN TO -10 TO -20 RANGE. A LITTLE EARLY TO ISSUE ANY KIND OF
HEADLINE BUT WILL MENTION IN HWO.
MONDAY-MONDAY NIGHT...H5 TROUGH AXIS WILL BEGIN TO NEAR THE AREA
DURING THE MORNING. CROSS SECTIONS THROUGH THE H85-H3 THICKNESS
GRADIENT INDICATE A DECENT AMOUNT OF FRONTOGENESIS AS TROUGH
APPROACHES...PARTICULARLY AROUND 675MB. SAME PROBLEM AS SUNDAY IS
APPARENT ON THIS CROSS SECTION THOUGH...ENTIRE AIRMASS ABOVE FRONTAL
SURFACE IS NOT SATURATED...AND BY MONDAY AFTERNOON IS FAIRLY DRY.
POINT SOUNDINGS HOWEVER INDICATE THE SURFACE TO THE FRONTAL
INVERSION SHOULD FALL INTO THE DENDRITIC GROWTH ZONE...SO WE MAY
SEE FAIRLY WIDESPREAD VERY LIGHT SNOW/FLURRIES DURING THE DAY...EVEN
THOUGH BEST FORCING IS IN DRY LAYER. OVERALL WOULD NOT ANTICIPATE
MUCH IN THE WAY OF ACCUMULATION AT THIS TIME...BUT DID BUMP UP POPS
SOMEWHAT ON MONDAY. VERY COLD AIR LOOKING TO BE OVER THE REGION AT
THIS TIME WITH MODELS AVERAGING H85 TEMPS AROUND -15C DURING THE
AFTERNOON. BASED ON OBSERVED TEMPS UPSTREAM TODAY...WOULDNT BE
SURPRISED IF AIRMASS WAS EVEN COLDER THAN CURRENT MODELS. LOWERED MAX
TEMPS INTO SINGLE DIGITS/LOW TEENS...A BIT COLDER THAN OPERATIONAL
MODELS SUGGEST. OVERNIGHT LOWS WILL BE A TOUGH CALL AS SFC HIGH
PRESSURE WILL SETTLE OVER THE AREA RELAXING WINDS...AND WITH VERY
COLD TEMPS ALREADY IN PLACE...TEMPERATURES COULD REALLY PLUMMET.
CLOUDS MAY HOLD TEMPS UP...BUT WITH SUBSIDENCE OVERSPREADING THE
AREA THINK GOING COLD WILL BE THE WAY TO GO AND WENT WITH LOWS
SEVERAL DEGREES BELOW ZERO.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
NE...NONE.
CO...NONE.
&&
$$
KJ/JRM
</pre> ks
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GOODLAND KS
232 AM MST SAT JAN 19 2008
.DISCUSSION...
05Z WATER VAPOR IMAGERY/RUC ANALYSIS INDICATED SHORT WAVE TROUGH
SLIDING ACROSS SOUTHERN COLORADO AROUND BASE OF LONG WAVE TROUGH
ACROSS EASTERN CONUS. LEADING EDGE OF 110KT H3 JET STREAK WAS
BEGINNING TO MOVE ACROSS AREA BEHIND TROUGH. AT THE SFC...1033MB HIGH
WAS DRAPED ACROSS NEBRASKA AND KANSAS...AND SFC TROUGH WAS LOCATED
ACROSS SE CO. OVERALL...BOTH THE NAM AND GFS INITIALIZED RELATIVELY
WELL AT 00Z. ALTHOUGH AT H3 BOTH MODELS SEEMED TO BE TO FAR NORTH
WITH JET MAX BEHIND SE CO TROUGH.
TODAY-TONIGHT...PRECIPITATION CHANCES...IF ANY THROUGH THE MORNING HOURS
WILL BE THE FIRST PROBLEM TO DEAL WITH TODAY. PREVIOUSLY MENTIONED
SHORT WAVE TROUGH WILL BE TO THE SOUTH OF THE WEST OF THE AREA BY
12Z TODAY AND ANY LINGERING PRECIPITATION WITH THAT WILL BE WELL
AWAY FROM THE AREA...HOWEVER 110KT JET STREAK LEFT ENTRANCE REGION
WILL BE OVER THE AREA. AS TROUGH SHIFTS EAST...DEEP WARM AIR
ADVECTION WILL ALSO BE TAKING PLACE AS RIDGE BUILDS IN. AS
TEMPERATURES WARM...AREA OF STEEPER LAPSE RATES OBSERVED ON KDNR RAOB
WILL SHIFT WILL ALSO SHIFT TO THE EAST AND NOT REALLY BE LINED UP
THAT GREAT WITH AVAILABLE ISENTROPIC ASCENT. DEEP LAYER DIV Q VECTORS
SUGGEST THAT SUBSIDENCE FROM BUILDING RIDGE WILL GENERALLY BEAT OUT
TEMPERATURE ADVECTION EFFECTS...ALTHOUGH H7-H5 LAYER DOES SUPPORT
SOME FORCING FOR ASCENT ACROSS CENTRAL PARTS OF THE AREA BY AROUND
12Z. CROSS SECTIONS ALSO SHOW FAIRLY DEEP FRONTOGENESIS ALL ALONG
TEMP GRADIENT ACROSS THE AREA WITH POCKET OF POTENTIAL INSTABILITY
JUST ABOVE FRONTAL SURFACE. MAIN QUESTION IS WHETHER OR NOT THIS
LAYER WILL BE SATURATED OR NOT. NAM AND GFS...DESPITE LARGE
DIFFERENCES IN QPF (DRY VS LIGHT) ACTUALLY SEEM TO HAVE VERY SIMILAR
FORCING STABILITY FIELDS WITH BIG DIFFERENCE IN HOW DRY AIRMASS
BELOW FRONTAL SURFACE IS. WITH OBSERVED SOUNDINGS UPSTREAM TENDING
TO SUPPORT DRIER NAM. FOR NOW THINK WILL GO WITH FLURRIES IN THE
MORNING AND ADJUST BASED ON EARLY MORNING TRENDS. RIDGE WILL BEGIN
TO FLATTEN OVERNIGHT WITH PERSISTENT...WEAK...WARM AIR ADVECTION
ACROSS MUCH OF THE AREA ESPECIALLY BETWEEN H7 AND H5. CROSS SECTIONS
ACROSS THE AREA ALONG WITH POINT SOUNDINGS INDICATE AREA WITH WEAK
LIFT ALSO VERY STABLE. ALTHOUGH THERE APPEARS TO BE WEAK LIFT IN A
SATURATED DENDRITIC LAYER ACROSS THE NORTH...THINK WEAK FORCING
AND STABLE AIRMASS WOULD NOT BE ABLE TO PRODUCE ANYTHING STRONG
ENOUGH TO MAKE IT THROUGH VERY DRY LAYER JUST OFF THE SURFACE.
SUNDAY-SUNDAY NIGHT...NEXT SHORT WAVE TROUGH WILL BEGIN TO MOVE INTO
THE WESTERN CONUS THROUGH THE DAY. SFC LOW WILL DEVELOP ACROSS
EASTERN COLORADO IN RESPONSE AND SLOWLY MOVE SOUTH...BRINGING A COLD
FRONT ACROSS THE AREA IN THE PROCESS. SHORT RANGE MODELS ALL BEGIN
TO BREAK OUT LIGHT PRECIP ACROSS THE AREA BEHIND THE FRONT...MAINLY
IN THE EVENING. SOUNDINGS WOULD SUGGEST THAT PRECIPITATION
PROCESSES WILL BE VERY SHALLOW AS ATMOSPHERE WILL BE SATURATED FROM
ONLY H8 AND DOWN. WITH EASTERLY WINDS ENHANCING ANY LARGE SCALE
FORCING ABOVE THE FRONTAL SURFACE THINK THERE WILL BE A CHANCE FOR
SOME VERY LIGHT PRECIP IF BOUNDARY LAYER CAN SATURATE. ALTHOUGH
MODELS SUGGEST THIS WILL HAPPEN...LOOKING AT HOW DRY THE AIR IS TO
THE EAST OF THE CWA CURRENTLY AM WORRIED THAT MODELS MAY BE
OVERDOING AVAILABLE MOISTURE...ESPECIALLY WHEN FLOW BEGINS TO
BECOME NORTHEAST BEHIND THE FRONT. SOUNDINGS ACTUALLY LOOK ALOT LIKE
A DRIZZLE/FREEZING DRIZZLE SOUNDING WITH SHALLOW SATURATED LAYER
CAPPED BY FAIRLY STRONG SHEAR. ATMOSPHERE WILL GRADUALLY COOL BEHIND
THE FRONT...BUT THERE COULD BE A WINDOW OF LIGHT FZDZ BEFORE THINGS
CHANGE OVER TO LIGHT SNOW. OVERNIGHT...DIV Q FIELDS INDICATE LARGE
SCALE FORCING FOR ASCENT BEGIN TO INCREASE ACROSS THE NORTHWEST CWA
AS TROUGH APPROACHES. THIS IS ALSO ACCOMPANIED BY INCREASING
FRONTOGENESIS BETWEEN H7 AND H6. STILL CONCERNED ABOUT PERSISTENT
DRY LVL MAY HINDER PRECIPITATION FORMATION AND KEEP THINGS
SHALLOW...BUT WILL PUT HIGHEST POPS IN THE NORTHWEST TO ACCOUNT FOR
BETTER FORCING. WINDS SHOULD STAY IN THE 10 TO 20 MPH RANGE
OVERNIGHT AS FRONT MOVES THROUGH THE AREA...AND WITH THE EXPECTED
VERY COLD AIR EXPECTED BEHIND THE FRONT THINK WE WILL SEE WIND
CHILLS IN TO -10 TO -20 RANGE. A LITTLE EARLY TO ISSUE ANY KIND OF
HEADLINE BUT WILL MENTION IN HWO.
MONDAY-MONDAY NIGHT...H5 TROUGH AXIS WILL BEGIN TO NEAR THE AREA
DURING THE MORNING. CROSS SECTIONS THROUGH THE H85-H3 THICKNESS
GRADIENT INDICATE A DECENT AMOUNT OF FRONTOGENESIS AS TROUGH
APPROACHES...PARTICULARLY AROUND 675MB. SAME PROBLEM AS SUNDAY IS
APPARENT ON THIS CROSS SECTION THOUGH...ENTIRE AIRMASS ABOVE FRONTAL
SURFACE IS NOT SATURATED...AND BY MONDAY AFTERNOON IS FAIRLY DRY.
POINT SOUNDINGS HOWEVER INDICATE THE SURFACE TO THE FRONTAL
INVERSION SHOULD FALL INTO THE DENDRITIC GROWTH ZONE...SO WE MAY
SEE FAIRLY WIDESPREAD VERY LIGHT SNOW/FLURRIES DURING THE DAY...EVEN
THOUGH BEST FORCING IS IN DRY LAYER. OVERALL WOULD NOT ANTICIPATE
MUCH IN THE WAY OF ACCUMULATION AT THIS TIME...BUT DID BUMP UP POPS
SOMEWHAT ON MONDAY. VERY COLD AIR LOOKING TO BE OVER THE REGION AT
THIS TIME WITH MODELS AVERAGING H85 TEMPS AROUND -15C DURING THE
AFTERNOON. BASED ON OBSERVED TEMPS UPSTREAM TODAY...WOULDNT BE
SURPRISED IF AIRMASS WAS EVEN COLDER THAN CURRENT MODELS. LOWERED MAX
TEMPS INTO SINGLE DIGITS/LOW TEENS...A BIT COLDER THAN OPERATIONAL
MODELS SUGGEST. OVERNIGHT LOWS WILL BE A TOUGH CALL AS SFC HIGH
PRESSURE WILL SETTLE OVER THE AREA RELAXING WINDS...AND WITH VERY
COLD TEMPS ALREADY IN PLACE...TEMPERATURES COULD REALLY PLUMMET.
CLOUDS MAY HOLD TEMPS UP...BUT WITH SUBSIDENCE OVERSPREADING THE
AREA THINK GOING COLD WILL BE THE WAY TO GO AND WENT WITH LOWS
SEVERAL DEGREES BELOW ZERO.
&&
.AVIATION...FOR THE 06Z TAF...THE LIGHT SNOW HAS MOVED TO THE SOUTH
OF BOTH TAF SITES. PERSISTENT MIDDLE AND UPPER LEVEL LIFT WILL KEEP
CLOUD COVER ACROSS THE AREA. HOWEVER...EVEN WITH ALL THE
CLOUDS...THE CEILINGS SHOULD REMAIN VFR EXCEPT FOR THE KMCK TAF THIS
AFTERNOON. AT THAT TIME...CEILINGS SHOULD DROP INTO THE HIGH END OF
THE MVFR RANGE. WINDS WILL REMAIN LIGHT AND GRADUALLY SWING AROUND
TO THE SOUTH AND SOUTHWEST AS THE DAY PROGRESSES.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
NE...NONE.
CO...NONE.
&&
$$
JRM/BULLER
</pre> ks
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GOODLAND KS
1029 PM MST FRI JAN 18 2008
.AVIATION...FOR THE 06Z TAF...THE LIGHT SNOW HAS MOVED TO THE
SOUTH OF BOTH TAF SITES. PERSISTANT MIDDLE AND UPPER LEVEL LIFT
WILL KEEP CLOUD COVER ACROSS THE AREA. HOWEVER...EVEN WITH ALL THE
CLOUDS...THE CEILINGS SHOULD REMAIN VFR EXCEPT FOR THE KMCK TAF
THIS AFTERNOON. AT THAT TIME...CEILINGS SHOULD DROP INTO THE HIGH
END OF THE MVFR RANGE. WINDS WILL REMAIN LIGHT AND GRADUALLY SWING
AROUND TO THE SOUTH AND SOUTHWEST AS THE DAY PROGRESSES.
&&
.PREV DISCUSSION... /ISSUED 836 PM MST FRI JAN 18 2008/
.UPDATE...JUST COMPLETED ANOTHER UPDATE. WHAT LOOKED PROMISING
EARLIER FOR SOME MEASURABLE SNOW DID NOT MATERIALIZE...MAINLY TO
THE EAST OF THE COLORADO BORDER. HAS BEEN SNOWING NEARLY 2 HOURS
AT KITR JUST 30 MILES AWAY. HOWEVER...NOT EVEN A FLAKE AT KGLD.
VERY TIGHT GRADIENT. MOST OF THE LIFT AND MOISTURE WILL REMAIN
OVER THE SOUTHWEST QUARTER OF THE FORECAST AREA THROUGH THE REST
OF TONIGHT. SO WILL KEEP LIKELY THERE.
ALSO LOWERED MINS...MAINLY IN THE EAST WHERE THE LEAST AMOUNT OF CLOUD
COVER RESIDES. ALSO UPDATED WINDS ON LASTEST OBSERVATIONS AND RUC.
WOULD HAVE LIKED TO HAVE TAKEN SNOW OUT OF TOMORROW MORNING SINCE
BELIEVE IT WILL BE ALL DONE BY THEN. HOWEVER...WILL LET IT RIDE SO
CAN STAY WITHIN COLLABORATION THRESHOLDS.
&&
.PREV DISCUSSION... /ISSUED 547 PM MST FRI JAN 18 2008/
.UPDATE...JUST COMPLETED AN UPDATE. COVERAGE AND INTENSITY OF SNOW
ALREADY PICKING BASED LATEST SATELLITE...RADAR...AND SURFACE
OBSERVATIONS. GFS LOOKS TO BE CAPTURING THE SNOW AREA THE BEST.
RADAR AND SATELLITE INDICATING SOME BANDED STRUCTURE. PROFILER
NETWORK SHOWING AREA IN WEAK RIGHT REAR QUADRANT OF THE JET. VERY
GOOD LAPSE RATES IN PLACES AS STRONG MID LEVEL LIFT/FRONTOGENESIS
IS MOVING ACROSS. SO RAISED THE POPS...QPF...AND SNOWFALL AMOUNTS
IN THE WESTERN HALF TO TWO THIRDS WHERE THE BEST MOISTURE AND LIFT
LINE UP. HAVE AMOUNTS OF 1 TO 2 INCHES. HOWEVER...IF THE GFS QPF
ENDS UP BEING RIGHT...I AM TOO LOW.
ALSO LOOKS LIKE SOME LINGERING MID AND JET LEVEL LIFT LINGERS INTO
THE 6Z TO 12Z TIME FRAME. HOWEVER...DEEPER MOISTURE DECREASES/MOVES
TO THE SOUTH DURING THIS TIME. SO KEPT POPS AND WX IN FOR THE
ENTIRE 12 HOUR PERIOD. WILL FINE TUNE LATER AS TRENDS INDICATE.
ALSO TWEEKED HOURLY TRENDS ON OTHER ELEMENTS BASED ON CURRENT TRENDS.
&&
.PREV DISCUSSION... /ISSUED 450 PM MST FRI JAN 18 2008/
.AVIATION...ISOLATED FLURRIES TO VERY LIGHT SNOW SHOWERS WILL
SPREAD ACROSS THE TRI-STATE REGION AND INCREASE IN COVERAGE BETWEEN
00Z-06Z. VFR CONDITIONS WILL BECOME MVFR WITH LOWER CEILINGS AND
VISIBILITIES WITH INTERMITTENT IFR CONDITIONS AND LIGHT SNOW
SHOWERS ENDING BETWEEN 08Z-10Z. MVFR CONDITIONS WILL THEN IMPROVE
TO VFR BETWEEN 11-13Z.
&&
.PREV DISCUSSION... /ISSUED 212 PM MST FRI JAN 18 2008/
.DISCUSSION...FORECAST CONCERNS INCLUDE TIMING OF ISOLATED FLURRIES IN
THE SHORT TERM...ENDING SATURDAY MORNING...AND MORE WIDESPREAD
LIGHT SNOW FROM SUNDAY NIGHT THROUGH MONDAY NIGHT.
ALSO...UNCERTAIN HOW COLD THE LOWS WILL BE BEHIND THE STRONG COLD
FRONT ON MONDAY.
BROAD LARGE SCALE TROUGH IS BEGINNING TO SLOWLY TRANSLATE
EASTWARD THROUGH THE CENTRAL CONUS...BUT NOT BEFORE A FEW VERY SMALL
DISTURBANCES ALONG THE FAR WESTERN EDGE OF THAT TROUGH INITIATE
SOME ISOLATED TO SCATTERED LIGHT SNOW UPSTREAM OF THE GLD CWA.
EXPECT THESE FLURRIES OR LIGHT SNOW SHOWERS TO ARRIVE HERE AFTER
00Z AND FINISH BY 09Z LEAVING LIGHT SNOWFALL AMOUNTS TOTALING A
TRACE TO ONE INCH. A BRIEF PERIOD OF SOUTHERLY WINDS ON SATURDAY
WILL CONTRIBUTE TO SLIGHTLY WARMER TEMPERATURES AHEAD OF A STRONG
PUSH OF ARCTIC AIR FROM THE NORTH.
SUNDAY THROUGH MONDAY...NEXT UPPER TROUGH DIGS DOWN THROUGH THE WESTERN
CONUS BEGINNING LATE SUNDAY WHILE DRASTICALLY LOWERING TEMPERATURES
ACROSS THE CENTRAL CONUS. HIGH TEMPERATURES ON MONDAY EXPECTED TO
ONLY REACH INTO THE MID TEENS WITH LOW TEMPERATURES ON TUESDAY
MORNING EASILY REACHING THE ZERO TO NEGATIVE 5 DEGREE RANGE. MODEL
TRENDS INDICATE ARRIVAL OF PRECIPITATION WITH THIS SYSTEM WILL BE
SLOWED WHEN COMPARED TO PREVIOUS MODEL RUNS. ADJUSTED POP AND
WEATHER GRIDS TO REFLECT THIS. PRECIPITATION ENDS LATE MONDAY INTO
EARLY TUESDAY. AS THIS LARGE SCALE TROUGH WASHES OUT OVER THE
INTER-MOUNTAIN WEST...SOUTHWESTERLY TO NEAR ZONAL UPPER FLOW
PERSISTS THROUGH THE REST OF THE WEEK WITH TEMPERATURES ONLY
GRADUALLY MODERATING.
&&
.EXTENDED...THURSDAY & FRIDAY... UPPER FLOW BECOMES SOMEWHAT ZONAL DURING THE
BEGINNING OF THIS PERIOD...ALLOWING TEMPERATURES TO RISE A BIT FROM THE
BITTER COLD TEMPERATURES SEEN EARLIER IN THE WEEK. EVEN WITH THAT
BEING SAID...THE TEMPERATURES ARE NOT EXPECTED TO RISE ABOVE
FREEZING ON THURSDAY BUT SHOULD WARM UP INTO THE MID 30S BY FRIDAY
AS THE SURFACE HIGH PRESSURE CONTINUES TO PUSH EAST AND WE RETURN TO
SOUTHERLY FLOW. THE EUROPEAN BRINGS AN H5 LOW OVER THE REGION FRIDAY
WHILE THE GFS BRINGS IN A FEW SHORTWAVE TROUGHS...HAVE KEPT POPS
RELATIVELY LOW AT THIS POINT AS UNCERTAINTY AT THIS RANGE OF TIME IS
HIGH.
&&
.AVIATION...CLOUD COVER WILL GRADUALLY INCREASE ACROSS KGLD & KMCK THROUGHOUT
THE TAF PERIOD. VFR CONDITIONS WILL PREVAIL THROUGH 21Z...AFTERWARDS
MVFR CONDITIONS WILL EXIST THROUGH 08Z WITH CEILINGS AROUND 2K AND
SOME LIGHT SNOW. VFR CONDITIONS SHOULD RETURN TO THE TERMINALS
AFTER 08Z.
&&
&&
&&
&&
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
NE...NONE.
CO...NONE.
&&
$$
BULLER
</pre> ks
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
354 AM CST SAT JAN 19 2008
.DISCUSSION...
MAIN FORECAST CONCERN IN THE NEAR TERM IS BITTERLY COLD TEMPERATURE
REGIME WITH SUB-ZERO WIND CHILLS IN NORTHERN AREAS THIS MORNING. OUR
FOCUS THEN TURNS TO THE CHANCE OF PRECIPITATION WITH THE NEXT SYSTEM
MONDAY NIGHT AND TUESDAY.
COLD FRONT JUST DEPARTING THE PENNYRILE REGION OF WESTERN KENTUCKY
THIS MORNING. SATELLITE INDICATES BROKEN SKY CONDITION OVER MUCH OF
THE AREA...BUT CLEARING SHOULD PROGRESS FAIRLY QUICKLY FROM WEST TO
EAST THIS MORNING SAVE FOR SOME LINGERING HIGH CLOUDS SOUTHEAST OF
THE OHIO RIVER. SIGNIFICANT COLD AIR ADVECTION WILL CONTINUE THROUGH
MID MORNING...WITH TEMPERATURES POSSIBLY BOTTOMING OUT NEAR 10
DEGREES BY 8 OR 9 AM NEAR MOUNT VERNON ILLINOIS. PAIRED WITH
NORTHWEST WINDS OF 10 TO 15 MPH...THIS WILL CREATE SUB-ZERO WIND
CHILLS OVER NORTHERN PORTIONS OF SOUTHEAST MISSOURI...SOUTHERN
ILLINOIS...AND INTO SOUTHWEST INDIANA. WILL HEADLINE FORECAST
ACCORDINGLY. LATER TODAY...TEMPERATURES WILL HAVE A HARD TIME
RECOVERING DESPITE ABUNDANT SUNSHINE. MET GUIDANCE APPEARS TO HAVE
THE BEST HANDLE ON THE INCOMING COLD AIR...AND THAT STILL DOESN/T
SEEM COLD ENOUGH. DECIDED TO UTILIZE RUC SURFACE TEMPERATURE
FORECAST INSTEAD FOR MUCH OF THE DAY.
TONIGHT WILL BE THE COLDEST NIGHT OF THE NEXT SEVEN DAYS...WITH LOWS
BOTTOMING OUT IN THE SINGLE DIGITS EXCEPT NEAR THE TENNESSEE AND
ARKANSAS STATE LINES. AGAIN...MET GUIDANCE IS PREFERRED.
TEMPERATURES WILL BEGIN TO MODERATE ON SUNDAY AS A WARM ADVECTION
PATTERN BECOMES ESTABLISHED OVER THE PLAINS. ANY PRECIPITATION
SHOULD REMAIN NORTHWEST OF THE REGION...BUT MID AND HIGH LEVEL
CLOUDINESS WILL LIKELY SPILL INTO THE AREA.
NEXT WEATHER SYSTEM WILL IMPACT THE AREA LATE MONDAY INTO TUESDAY...
WITH PRECIPITATION TYPE THE MAIN CONCERN. 18/18Z AND 19/00Z GFS AND
19/00Z ECMWF OPERATIONAL RUNS ARE VERY SIMILAR IN DEVELOPING
SOUTHERLY FLOW ACROSS THE IMMEDIATE AREA AS THE SURFACE LOW TRACKS
TO OUR NORTH TOWARDS CHICAGO BY 06Z TUESDAY. AS A RESULT...
OPERATIONAL MOS GUIDANCE IS NOW FORECASTING HIGH TEMPERATURES IN THE
40S MONDAY...WITH READINGS NEAR FREEZING BY LATE MONDAY NIGHT. TO
COMPLICATE MATTERS EVEN MORE...GFS FORECAST SOUNDINGS ARE NOT
CONVINCING THAT ICE NUCLEATION WILL TAKE PLACE FOR SNOW CRYSTAL
GROWTH GIVEN THE DRY AIR IN THE MID LEVELS. THE SCALES CERTAINLY
SEEM TO BE WEIGHING MORE IN FAVOR OF LIQUID VERSUS FROZEN
PRECIPITATION FOR MUCH OF THIS EVENT. HOWEVER...DEPENDING UPON THE
AMOUNT OF DRY AIR IN THE BOUNDARY LAYER...THE ELEMENT OF EVAPORATIVE
COOLING MAY ULTIMATELY BE THE DECIDING FACTOR. FOR NOW...WE TRENDED
TOWARDS A SLIGHTLY WARMER SOLUTION BY STARTING THE EVENT OUT AS A
MIX OF RAIN/SNOW NORTH...AND ALL RAIN SOUTH MONDAY EVENING. THEN
TRANSITIONED TO ALL SNOW NORTH AND A MIX OF RAIN/SNOW SOUTH
OVERNIGHT INTO TUESDAY. NONETHELESS...MODEL QPF FORECASTS ARE STILL
RELATIVELY LIGHT...SO NOT A MAJOR EVENT AT THIS POINT.
NO CHANGES WERE NECESSARY BEYOND TUESDAY.
&&
.AVIATION...
EXPECT A BAND OF MVFR CEILINGS (1500-2500 FT) TO MOVE ACROSS THE
REGION THROUGH AROUND SUNRISE. VFR CONDITIONS SHOULD PREVAIL THE
REMAINDER OF THE TAF PERIOD. ARCTIC FRONT IS NOW THROUGH ALL TAF
SITES. EXPECT NW WINDS TO GUST TO AROUND 15 KTS TODAY...THEN DIE OUT
THIS EVENING.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
MO...NONE.
IL...NONE.
IN...NONE.
&&
$$
RJP/GM
</pre> ky
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
1057 PM EST SUN JAN 20 2008
.UPDATE...NEW UPDATE IS OUT AS THE SNOW BANDS CONTINUE TO
DIMINISH DUE TO DRY AIR INTRUSION. SO HAVE DROPPED THE WINTER
WEATHER ADVISORY AS THE SNOW AND BLOWING SNOW ISN`T LOWERING THE
VISIBILITY SUBSTANTIALLY.
LUTZ
&&
.PREV DISCUSSION... /ISSUED 958 PM EST SUN JAN 20 2008/
UPDATE...SO FAR, THE FORECAST LOOKS LIKE IT IS DOING WELL WITH
THE SNOW BANDS LOOKING LIKE THEY ARE BEGINNING TO TAPER OFF NEAR
APN AND TVC. NEW NAM AND RUC LOOK TO BEAR OUT WHAT IS GOING ON IN
N LOWER. E UPPER LOOKS LIKE IT WILL CONTINUE TO GET SNOW BANDS
AFFECTING ANJ, WHITEFISH POINT, AND PARADISE. SO WILL LET THE
WINTER WEATHER ADVISORY EXPIRE AT 11 PM AND WILL CONTINUE THE LES
WARNING IN E UPPER. IT LOOKS LIKE THE 1000-850 MB STREAMLINES WILL
BEGIN TO COME OUT OF THE SW, WHICH WILL BRING IN MORE DRY AIR. SO
THE FORECAST LOOKS TO BE ON TRACK FOR NOW. ZONES WILL BE OUT
CLOSER TO 11 PM TO LET THE WWA EXPIRE.
LUTZ
PREV DISCUSSION... /ISSUED 749 PM EST SUN JAN 20 2008/
AVIATION...ADJUSTED FOR THE SNOW BANDS AS THE WINDS REALIGN FOR
THE NIGHT AND THE DAYTIME CONVECTION SETTLES DOWN. MAIN CONCERN
OVER THE NEXT FEW HOURS WILL BE THE DRY AIR MOVING INTO THE REGION
AND SUPPRESSING THE LAKE EFFECT SNOW SHOWERS. SO FAR, IT LOOKS
LIKE THE DRY AIR WILL CAUSE THE SNOW SHOWERS AT TVC AND PLN TO TAPER
OFF TO FLURRIES, AND STOP THE SNOW AT APN. CLOUD COVER WILL BE
PROBLEMATIC WITH DRY AIR, YET SEEING WHERE THE CONVECTION CAN DRAW
ON THE LAKE MOISTURE TO KEEP SOME CLOUDS.
LUTZ
PREV DISCUSSION... /ISSUED 333 PM EST SUN JAN 20 2008/
DISCUSSION...SUBSTANTIALLY DRIER AIR PRESSING ACROSS LAKE MICHIGAN
(OUT OF THE WISCONSIN DEEP FREEZE) COUPLED WITH SOME DAYTIME
"HEATING" HAS LEAD TO AN OVERALL DIMINISHING TREND TO THE LAKE
EFFECT SNOWS (NOTE EASTWARD SHRINKING LAKE STCU). INLAND SNOW SHOWER
COVERAGE HAS ACTUALLY EXPANDED A BIT WITH THE INLAND CONVECTIVE
CYCLE...BUT MOST OF WHICH WILL FADE EARLY THIS EVENING. TO THE
NORTH...OUTSIDE OF AREAS AROUND WHITEFISH BAY...NOT A BAD DAY IN THE
EASTERN U.P. WITH QUITE A BIT OF SUNSHINE DESPITE THE VERY COLD
TEMPS. FORECAST ISSUES TONIGHT REVOLVE AROUND DISPOSITION OF ONGOING
WARNING AND ADVISORIES.
TONIGHT...ACROSS NORTHERN LOWER MICHIGAN: W/WNW FLOW LOOKING TO
REMAIN LOCKED THROUGHOUT THE NIGHT WITH MORE THAN AMPLE OVER WATER
INSTABILITY. BUT MEANWHILE...VERY DRY UPSTREAM AIR (NEGATIVE TEEN
DEWPOINTS IN WISCONSIN) WILL CONTINUE TO ADVECT EASTWARD ACROSS THE
LAKE AND SHOULD KEEP OVERALL LAKE EFFECT INTENSITY IN CHECK. HIGH
POPS FOR THE W/WNW FLOW AREAS ARE JUSTIFIED HOWEVER...GIVEN THE
FANTASTIC OVER WATER INSTABILITY...BUT WILL LIMIT OVERALL
ACCUMULATIONS TO UNDER 3 INCHES. AS FAR AS THE ADVISORY IS
CONCERNED...CONSIDERED CANCELING THE HEADLINE GIVEN THE TRENDS IN
THE LES INTENSITY. HOWEVER...WITH THE SMALL FLAKE SIZES AND GUSTY
WINDS/BLSN VSBYS CONTINUE TO BE A PROBLEM THIS AFTERNOON AND WILL
REMAIN AN ISSUE AT LEAST THROUGH EARLY-MID EVENING. SO...PLAN ON
STRETCHING OUT THE ADVISORY FOR AREAS NORTH OF M-72 (WHERE MOST
INTENSE SNOW SHOWERS NOW RESIDE) THROUGH THE EVENING HOURS...BUT
FOCUS MORE ON THE LOW VSBYS AND WIND CHILL ASPECTS. WILL TRIM OUT
GRAND TRAVERSE COUNTY OVER TO CRAWFORD COUNTY.
EASTERN UPPER MICHIGAN: DIFFERENT PROBLEMS HERE. PER MONTREAL RIVER
RADAR AND SATELLITE IMAGERY...FAIRLY HEFTY SNOW SHOWERS ONCE AGAIN
IMPACTED THE WHITEFISH BAY AREA. 12Z NAM/GFS SOLUTIONS PEG BULLSEYE
OF LOW LEVEL CONVERGENCE OVER THE SE CORNER OF THE LAKE/NRN CHIPPEWA
COUNTY TONIGHT. AND GIVEN THE GREAT INSTABILITY/LONG FETCH
LENGTHS...THINK AT LEAST ANOTHER 3-6 INCHES OF SNOW A GOOD BET FOR
THAT AREA WITH BETTER SNOW SHOWER ACTIVITY IMPACTING AREAS EASTWARD
INTO ANJ. GIVEN THIS...WILL STRETCH THE WARNING OUT FOR ANOTHER
FORECAST PERIOD.
ADAM
MONDAY THROUGH TUESDAY...A COLD START TO MONDAY MORNING WITH PARTLY
CLOUDY SKIES ACROSS MUCH OF NE LOWER...AND PORTIONS OF EASTERN
UPPER. MID AND HIGH LEVEL CLOUDS WILL BE STREAMING IN AHEAD OF
SHORTWAVE AND DEVELOPING TIGHT THERMAL GRADIENT/INVERTED TROUGH. SO
EXPECT SKIES TO CLOUD UP QUICKLY. THE THERMAL GRADIENT LAYS OUT
ACROSS NRN LOWER WITH MODEST 280-295K ISENTROPIC ASCENT AND MARGINAL
FGEN RESPONSE FROM MAINLY MIDDAY MONDAY THROUGH MONDAY EVENING. BEST
SYNOPTIC FORCING...MAINLY DUE TO WARM ADVECTION WILL BE ACROSS SRN
WISCONSIN...BUT THIS FORCING ALONE WILL BRING A GOOD 2-3 INCHES
ACROSS NRN LOWER. AIR MASS WILL BE MODERATING THROUGH THE
EVENING...WITH THE REAL COLD H8 TEMPS WARMING TO FAVORABLE -14C TO
-18C RANGE AT THE ONSET AND FOR THE DURATION OF THE SYNOPTIC
SNOWFALL. THE KEY HERE WILL BE THE ADDITION OR ENHANCEMENT FROM THE
LAKES. FAVORABLE H8 REGIME WITH BOUNTIFUL ICE CRYSTALS IN CLOUD TOP
LAYER SHOULD RESULT IN LARGE FLAKES...POSSIBLY MANY...FOR A PERIOD
INTO MONDAY EVENING. TROUGH SLIPS BY TUES AND H8 TEMPS COOL TO A
STILL RESPECTABLE -18C/-19C. THUS...FAVORABLE THERMODYNAMICS THROUGH
THE PERIOD...WITH DEEP MOISTURE AND FORCING...WHILE INVERSION
HEIGHTS AVERAGE 6KFT WHEN USING PARCELS OFF THE LAKE. THE LAKES
ALONE SUGGEST MODERATE ACCUMULATIONS. WHEN ADDED TO THE SYNOPTIC
SNOWS...THE POTENTIAL IS THERE FOR HEAVY TOTAL SNOWFALL. THE
QUESTION THAT NEEDS TO BE ANSWERED WILL BE THE 1000-850MB WIND
DIRECTION. GFS HAS PROLONGED SW (230-240) FLOW WHILE NAM SHIFTS SW
WINDS TO DUE SOUTH BY MONDAY EVENING. THIS DIFFERENCE MEANS WAY TOO
MUCH TO PIN DOWN A PARTICULAR AREA. THEREFORE...AFTER MUCH
COORDINATION...WILL ISSUE A WINTER STORM WATCH FOR MAINLY SW FLOW
REGIMES. A SECONDARY SHORTWAVE DIVES INTO THE REGION TUESDAY WITH A
SHOT OF DEEPER MOISTURE...WHILE 1000-850MB WINDS ARE SHIFTING WEST
THEN NW. GOOD CYCLONIC CONVERGENCE IN PLACE AND INVERSION HEIGHTS
STEEPEN TO A DEEP 8-9KFT POSSIBLY. THOUGHT ABOUT ISSUING A WATCH TO
INCLUDE ALL OF THE NW FLOW REGIMES...BUT MIDNIGHT CREW HAS TIME TO
LOOK AT THIS. IT DOES LOOK LIKE SNOWS COULD START COMING DOWN HARD
TUESDAY AFTERNOON. HIGH WILL BE IN THE TEENS MONDAY AND
TUESDAY...WITH LOWS MONDAY NIGHT NOT DIPPING TOO FAR FROM THE TEENS.
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...STEEP INVERSION HEIGHTS
DROP TO A RESPECTABLE 5-6KFT...WHILE WEAK MID LEVEL RIDGING MOVES
IN. DEEPER MOISTURE STRIPS OUT ALOFT WHILE SFC HIGH PRESSURE TRIED
TO POKE ACROSS THE NRN OHIO VALLEY. WE LOSE THE CYCLONIC
CONVERGENCE...AND H8 TEMPS CONTINUE TO COOL TO THE LOWER -20S.
THERE ARE TOO MANY INCONSISTENCIES BETWEEN THE MODELS ON KEY LES
PARAMETERS...BUT THERE IS POTENTIAL FOR HEAVY SNOW INTO AT LEAST
TUESDAY EVENING FOR WNW/NW FLOW REGIMES. SHOULD SEE FLAKE SIZES
GET PROGRESSIVELY SMALLER WITH TIME. THESE DETAILS WILL BECOME
CLEARER OVER THE NEXT COUPLE OF DAYS. YET ANOTHER SHOT OF COLDER
AIR ARRIVES BY WEDNESDAY NIGHT...AS ONE MORE SHORTWAVE AND
ASSOCIATED SFC LOW WORKS INTO NRN MICHIGAN. THIS COULD SPELL
ANOTHER PERIOD OF SYNOPTIC SNOWS ENHANCED BY THE LAKES. WILL HAVE
TO WAIT AND SEE WITH THIS ONE. ALL-IN-ALL...SOME AREAS COULD BE
INVOLVED IN A PROLONGED PERIOD OF SNOWFALL. OBVIOUSLY...HEADLINES
WILL BE THE MAJOR ISSUE WITH TIME. HIGHS WEDNESDAY COOL DOWN TO
THE 6-14 RANGE WHILE LOWS WILL BE IN THE SINGLE DIGITS BOTH ABOVE
AND BELOW ZERO.
THURSDAY ONWARD...SCATTERED LAKE EFFECT SNOW SHOWERS THURSDAY LOOK
TO COME TO AN END FRIDAY WITH A GRADUAL WARMING OF THE BL AND
POSSIBLE END TO SUFFICIENT OVERLAKE INSTABILITY. WILL HAVE TO SEE
ON THIS...BUT SFC HIGH PRESSURE AND DRY AIR SLIDE ACROSS THE OHIO
RIVER VALLEY WITH OUR H8 TEMPS WARMING TO -8C OR SO. LEFT SOME
RESIDUAL SNOW SHOWERS IN NW FLOW REGIME THURSDAY...THEN SW THURSDAY
NIGHT. A DRY FRIDAY FOR NOW...BEFORE NEXT SHORTWAVE/FRONT ARRIVES
FRIDAY NIGHT INTO NEXT WEEKEND FOR CHANCE OF SNOW. SMD
AVIATION...ISSUED AT 111 PM.
MVFR CIGS/VSBYS CONTINUE AT PLN/TVC INTO EARLY EVENING DUE TO
CONTINUING LAKE EFFECT SNOW SHOWERS. SCATTERED SNOW SHOWERS WITH
OCCASIONALLY REDUCED VSBYS THIS AFTERNOON AT APN. SNOW SHOWER
ACTIVITY EXPECTED TO DIMINISH THIS EVENING AND OVERNIGHT WITH
IMPROVEMENT TO VFR CONDITIONS.
ADAM
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON
     FOR MIZ015-016-019>021-025-026-031-032.
     LAKE EFFECT SNOW WARNING UNTIL 5 AM EST MONDAY FOR MIZ008.
LM...SMALL CRAFT ADVISORY UNTIL 7 AM EST MONDAY FOR LMZ323-341-342-
     344>346.
LH...SMALL CRAFT ADVISORY UNTIL 7 AM EST MONDAY FOR LHZ345>349.
&&
$$
</pre> mi
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
958 PM EST SUN JAN 20 2008
.UPDATE...SO FAR, THE FORECAST LOOKS LIKE IT IS DOING WELL WITH
THE SNOW BANDS LOOKING LIKE THEY ARE BEGINNING TO TAPER OFF NEAR
APN AND TVC. NEW NAM AND RUC LOOK TO BEAR OUT WHAT IS GOING ON IN
N LOWER. E UPPER LOOKS LIKE IT WILL CONTINUE TO GET SNOW BANDS
AFFECTING ANJ, WHITEFISH POINT, AND PARADISE. SO WILL LET THE
WINTER WEATHER ADVISORY EXPIRE AT 11 PM AND WILL CONTINUE THE LES
WARNING IN E UPPER. IT LOOKS LIKE THE 1000-850 MB STREAMLINES WILL
BEGIN TO COME OUT OF THE SW, WHICH WILL BRING IN MORE DRY AIR. SO
THE FORECAST LOOKS TO BE ON TRACK FOR NOW. ZONES WILL BE OUT
CLOSER TO 11 PM TO LET THE WWA EXPIRE.
LUTZ
&&
.PREV DISCUSSION... /ISSUED 749 PM EST SUN JAN 20 2008/
AVIATION...ADJUSTED FOR THE SNOW BANDS AS THE WINDS REALIGN FOR
THE NIGHT AND THE DAYTIME CONVECTION SETTLES DOWN. MAIN CONCERN
OVER THE NEXT FEW HOURS WILL BE THE DRY AIR MOVING INTO THE REGION
AND SUPPRESSING THE LAKE EFFECT SNOW SHOWERS. SO FAR, IT LOOKS
LIKE THE DRY AIR WILL CAUSE THE SNOW SHOWERS AT TVC AND PLN TO TAPER
OFF TO FLURRIES, AND STOP THE SNOW AT APN. CLOUD COVER WILL BE
PROBLEMATIC WITH DRY AIR, YET SEEING WHERE THE CONVECTION CAN DRAW
ON THE LAKE MOISTURE TO KEEP SOME CLOUDS.
LUTZ
PREV DISCUSSION... /ISSUED 333 PM EST SUN JAN 20 2008/
DISCUSSION...SUBSTANTIALLY DRIER AIR PRESSING ACROSS LAKE MICHIGAN
(OUT OF THE WISCONSIN DEEP FREEZE) COUPLED WITH SOME DAYTIME
"HEATING" HAS LEAD TO AN OVERALL DIMINISHING TREND TO THE LAKE
EFFECT SNOWS (NOTE EASTWARD SHRINKING LAKE STCU). INLAND SNOW SHOWER
COVERAGE HAS ACTUALLY EXPANDED A BIT WITH THE INLAND CONVECTIVE
CYCLE...BUT MOST OF WHICH WILL FADE EARLY THIS EVENING. TO THE
NORTH...OUTSIDE OF AREAS AROUND WHITEFISH BAY...NOT A BAD DAY IN THE
EASTERN U.P. WITH QUITE A BIT OF SUNSHINE DESPITE THE VERY COLD
TEMPS. FORECAST ISSUES TONIGHT REVOLVE AROUND DISPOSITION OF ONGOING
WARNING AND ADVISORIES.
TONIGHT...ACROSS NORTHERN LOWER MICHIGAN: W/WNW FLOW LOOKING TO
REMAIN LOCKED THROUGHOUT THE NIGHT WITH MORE THAN AMPLE OVER WATER
INSTABILITY. BUT MEANWHILE...VERY DRY UPSTREAM AIR (NEGATIVE TEEN
DEWPOINTS IN WISCONSIN) WILL CONTINUE TO ADVECT EASTWARD ACROSS THE
LAKE AND SHOULD KEEP OVERALL LAKE EFFECT INTENSITY IN CHECK. HIGH
POPS FOR THE W/WNW FLOW AREAS ARE JUSTIFIED HOWEVER...GIVEN THE
FANTASTIC OVER WATER INSTABILITY...BUT WILL LIMIT OVERALL
ACCUMULATIONS TO UNDER 3 INCHES. AS FAR AS THE ADVISORY IS
CONCERNED...CONSIDERED CANCELING THE HEADLINE GIVEN THE TRENDS IN
THE LES INTENSITY. HOWEVER...WITH THE SMALL FLAKE SIZES AND GUSTY
WINDS/BLSN VSBYS CONTINUE TO BE A PROBLEM THIS AFTERNOON AND WILL
REMAIN AN ISSUE AT LEAST THROUGH EARLY-MID EVENING. SO...PLAN ON
STRETCHING OUT THE ADVISORY FOR AREAS NORTH OF M-72 (WHERE MOST
INTENSE SNOW SHOWERS NOW RESIDE) THROUGH THE EVENING HOURS...BUT
FOCUS MORE ON THE LOW VSBYS AND WIND CHILL ASPECTS. WILL TRIM OUT
GRAND TRAVERSE COUNTY OVER TO CRAWFORD COUNTY.
EASTERN UPPER MICHIGAN: DIFFERENT PROBLEMS HERE. PER MONTREAL RIVER
RADAR AND SATELLITE IMAGERY...FAIRLY HEFTY SNOW SHOWERS ONCE AGAIN
IMPACTED THE WHITEFISH BAY AREA. 12Z NAM/GFS SOLUTIONS PEG BULLSEYE
OF LOW LEVEL CONVERGENCE OVER THE SE CORNER OF THE LAKE/NRN CHIPPEWA
COUNTY TONIGHT. AND GIVEN THE GREAT INSTABILITY/LONG FETCH
LENGTHS...THINK AT LEAST ANOTHER 3-6 INCHES OF SNOW A GOOD BET FOR
THAT AREA WITH BETTER SNOW SHOWER ACTIVITY IMPACTING AREAS EASTWARD
INTO ANJ. GIVEN THIS...WILL STRETCH THE WARNING OUT FOR ANOTHER
FORECAST PERIOD.
ADAM
MONDAY THROUGH TUESDAY...A COLD START TO MONDAY MORNING WITH PARTLY
CLOUDY SKIES ACROSS MUCH OF NE LOWER...AND PORTIONS OF EASTERN
UPPER. MID AND HIGH LEVEL CLOUDS WILL BE STREAMING IN AHEAD OF
SHORTWAVE AND DEVELOPING TIGHT THERMAL GRADIENT/INVERTED TROUGH. SO
EXPECT SKIES TO CLOUD UP QUICKLY. THE THERMAL GRADIENT LAYS OUT
ACROSS NRN LOWER WITH MODEST 280-295K ISENTROPIC ASCENT AND MARGINAL
FGEN RESPONSE FROM MAINLY MIDDAY MONDAY THROUGH MONDAY EVENING. BEST
SYNOPTIC FORCING...MAINLY DUE TO WARM ADVECTION WILL BE ACROSS SRN
WISCONSIN...BUT THIS FORCING ALONE WILL BRING A GOOD 2-3 INCHES
ACROSS NRN LOWER. AIR MASS WILL BE MODERATING THROUGH THE
EVENING...WITH THE REAL COLD H8 TEMPS WARMING TO FAVORABLE -14C TO
-18C RANGE AT THE ONSET AND FOR THE DURATION OF THE SYNOPTIC
SNOWFALL. THE KEY HERE WILL BE THE ADDITION OR ENHANCEMENT FROM THE
LAKES. FAVORABLE H8 REGIME WITH BOUNTIFUL ICE CRYSTALS IN CLOUD TOP
LAYER SHOULD RESULT IN LARGE FLAKES...POSSIBLY MANY...FOR A PERIOD
INTO MONDAY EVENING. TROUGH SLIPS BY TUES AND H8 TEMPS COOL TO A
STILL RESPECTABLE -18C/-19C. THUS...FAVORABLE THERMODYNAMICS THROUGH
THE PERIOD...WITH DEEP MOISTURE AND FORCING...WHILE INVERSION
HEIGHTS AVERAGE 6KFT WHEN USING PARCELS OFF THE LAKE. THE LAKES
ALONE SUGGEST MODERATE ACCUMULATIONS. WHEN ADDED TO THE SYNOPTIC
SNOWS...THE POTENTIAL IS THERE FOR HEAVY TOTAL SNOWFALL. THE
QUESTION THAT NEEDS TO BE ANSWERED WILL BE THE 1000-850MB WIND
DIRECTION. GFS HAS PROLONGED SW (230-240) FLOW WHILE NAM SHIFTS SW
WINDS TO DUE SOUTH BY MONDAY EVENING. THIS DIFFERENCE MEANS WAY TOO
MUCH TO PIN DOWN A PARTICULAR AREA. THEREFORE...AFTER MUCH
COORDINATION...WILL ISSUE A WINTER STORM WATCH FOR MAINLY SW FLOW
REGIMES. A SECONDARY SHORTWAVE DIVES INTO THE REGION TUESDAY WITH A
SHOT OF DEEPER MOISTURE...WHILE 1000-850MB WINDS ARE SHIFTING WEST
THEN NW. GOOD CYCLONIC CONVERGENCE IN PLACE AND INVERSION HEIGHTS
STEEPEN TO A DEEP 8-9KFT POSSIBLY. THOUGHT ABOUT ISSUING A WATCH TO
INCLUDE ALL OF THE NW FLOW REGIMES...BUT MIDNIGHT CREW HAS TIME TO
LOOK AT THIS. IT DOES LOOK LIKE SNOWS COULD START COMING DOWN HARD
TUESDAY AFTERNOON. HIGH WILL BE IN THE TEENS MONDAY AND
TUESDAY...WITH LOWS MONDAY NIGHT NOT DIPPING TOO FAR FROM THE TEENS.
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...STEEP INVERSION HEIGHTS
DROP TO A RESPECTABLE 5-6KFT...WHILE WEAK MID LEVEL RIDGING MOVES
IN. DEEPER MOISTURE STRIPS OUT ALOFT WHILE SFC HIGH PRESSURE TRIED
TO POKE ACROSS THE NRN OHIO VALLEY. WE LOSE THE CYCLONIC
CONVERGENCE...AND H8 TEMPS CONTINUE TO COOL TO THE LOWER -20S.
THERE ARE TOO MANY INCONSISTENCIES BETWEEN THE MODELS ON KEY LES
PARAMETERS...BUT THERE IS POTENTIAL FOR HEAVY SNOW INTO AT LEAST
TUESDAY EVENING FOR WNW/NW FLOW REGIMES. SHOULD SEE FLAKE SIZES
GET PROGRESSIVELY SMALLER WITH TIME. THESE DETAILS WILL BECOME
CLEARER OVER THE NEXT COUPLE OF DAYS. YET ANOTHER SHOT OF COLDER
AIR ARRIVES BY WEDNESDAY NIGHT...AS ONE MORE SHORTWAVE AND
ASSOCIATED SFC LOW WORKS INTO NRN MICHIGAN. THIS COULD SPELL
ANOTHER PERIOD OF SYNOPTIC SNOWS ENHANCED BY THE LAKES. WILL HAVE
TO WAIT AND SEE WITH THIS ONE. ALL-IN-ALL...SOME AREAS COULD BE
INVOLVED IN A PROLONGED PERIOD OF SNOWFALL. OBVIOUSLY...HEADLINES
WILL BE THE MAJOR ISSUE WITH TIME. HIGHS WEDNESDAY COOL DOWN TO
THE 6-14 RANGE WHILE LOWS WILL BE IN THE SINGLE DIGITS BOTH ABOVE
AND BELOW ZERO.
THURSDAY ONWARD...SCATTERED LAKE EFFECT SNOW SHOWERS THURSDAY LOOK
TO COME TO AN END FRIDAY WITH A GRADUAL WARMING OF THE BL AND
POSSIBLE END TO SUFFICIENT OVERLAKE INSTABILITY. WILL HAVE TO SEE
ON THIS...BUT SFC HIGH PRESSURE AND DRY AIR SLIDE ACROSS THE OHIO
RIVER VALLEY WITH OUR H8 TEMPS WARMING TO -8C OR SO. LEFT SOME
RESIDUAL SNOW SHOWERS IN NW FLOW REGIME THURSDAY...THEN SW THURSDAY
NIGHT. A DRY FRIDAY FOR NOW...BEFORE NEXT SHORTWAVE/FRONT ARRIVES
FRIDAY NIGHT INTO NEXT WEEKEND FOR CHANCE OF SNOW. SMD
AVIATION...ISSUED AT 111 PM.
MVFR CIGS/VSBYS CONTINUE AT PLN/TVC INTO EARLY EVENING DUE TO
CONTINUING LAKE EFFECT SNOW SHOWERS. SCATTERED SNOW SHOWERS WITH
OCCASIONALLY REDUCED VSBYS THIS AFTERNOON AT APN. SNOW SHOWER
ACTIVITY EXPECTED TO DIMINISH THIS EVENING AND OVERNIGHT WITH
IMPROVEMENT TO VFR CONDITIONS.
ADAM
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON
     FOR MIZ015-016-019>021-025-026-031-032.
     WINTER WEATHER ADVISORY UNTIL 11 PM EST THIS EVENING FOR MIZ016-
     017-019-021-022.
     LAKE EFFECT SNOW WARNING UNTIL 5 AM EST MONDAY FOR MIZ008.
LM...SMALL CRAFT ADVISORY UNTIL 7 AM EST MONDAY FOR LMZ323-341-342-
     344>346.
LH...SMALL CRAFT ADVISORY UNTIL 7 AM EST MONDAY FOR LHZ345>349.
&&
$$
</pre> mi
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MARQUETTE MI
825 PM EST SUN JAN 20 2008
.UPDATE...
LES CONTINUES TO STREAM INTO THE ERN COUNTIES E OF P53 IN COLD WNW
FLOW ACRS LK SUP. SPOTTER REPORTS INDICATE THE LES IS NO LONGER
PARTICULARLY HVY...SO ALLOWED LES WRNG FOR ALGER/LUCE ZNS TO EXPIRE
AS SCHEDULED AT 00Z. HOWEVER...WINDS AT GRAND MARAIS HAVE BEEN 30-35
MPH ALL EVNG...SO POSTED AN LES/BLSN ADVY FOR ALGER/LUCE THRU THE
NGT WITH SEVERAL MORE INCHES OF FINE SNOW LIKELY. WITH BACKING LLVL
FLOW ENHANCED BY LAND BREEZE COMPONENT...THE SHSN WL CONTINUE TO
GRDLY SHIFT TO THE N AND IMPACT ONLY AREAS NEAR THE SHORELINE BY
LATE NGT. SINCE SHSN HAVE BEEN LIFTING SLOWLY TO THE N...DID NOT
EXTEND THE LES ADVY FOR NRN SCHOOLCRAFT. OTRW... OTHER LES/WIND
CHILLS HEADLINES SEEM ON TRACK EVEN THOUGH THERE IS SOME QUESTION AS
TO WHETHER WIND SPEEDS WL BE HI ENUF AT MOST PLACES WHERE WIND CHILL
ADVYS ARE IN EFFECT. BUT EVEN IF WIND SPEEDS DO NOT MEET THE
THRESHOLD REQUIREMENT...THE APRNT TEMP WL STILL BE LO ENUF TO
JUSTIFY KEEPING THE HEADLINES.
.SHORT TERM...
THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR
LAKE EFFECT SNOWS TONIGHT AND THE NEXT SYSTEM APPROACHING FROM THE
SOUTH ON MONDAY.
WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER EASTERN
CANADA. A CLOSED LOW CONTINUES TO DEVELOP OVER IDAHO. WEAK SHORTWAVE
SLIDING DOWN THE LEE OF THE RIDGE ARE OVER WISCONSIN AND EASTERN
U.P. SURFACE ANALYSIS DEPICTS A LARGE HIGH OVER EAST CENTRAL
ILLINOIS WITH THE ACCOMPANYING RIDGE STRETCHING NORTHWEST ACROSS THE
NORTHERN PLAINS INTO ALBERTA. A WEAK SURFACE TROUGH IS OVER EASTERN
LAKE SUPERIOR. AN 850MB THERMAL TROUGH CONTINUES TO SHIFT
EAST...WITH THE LAKE-850MB DELTA-T OF AROUND 28C THIS IS GENERATING
WEAK LOW LEVEL CONVERGENCE AND INSTABILITY. THE LOW LEVEL AIR MASS
IS STILL VERY DRY...WITH THE PRECIPITABLE WATER OF LESS THAN .1 OF
AN INCH. LAKE EFFECT SNOWS CONTINUE OVER THE COUNTIES ADJACENT TO
THE LAKE AND DOWNWIND OF WEST TO NORTHWEST WINDS.
THE LONGWAVE TROUGH WILL SHIFT EAST INTO THE CANADIAN MARITIME. AS
THE CLOSED LOW OVER IDAHO DEEPENS. A RIDGE WILL BE CLIMBING ASHORE
OVER SOUTHWEST CANADA. WEAK SHORTWAVE SLIDING DOWN THE LEE OF THE
RIDGE WILL MOVE INTO EASTERN AND CENTRAL ONTARIO TONIGHT AND SET UP
KIND OF A ZONAL FLOW ACROSS THE CENTRAL CONUS. MID LEVEL WINDS WILL
BACK A LITTLE MORE WEST OVER THE AREA TONIGHT. THE SURFACE HIGH WILL
SHIFT TO EASTERN OHIO RIVER VALLEY. LOW LEVEL CONVERGENCE ALONG THE
LAKE SHORE WILL KEEP SOME LAKE EFFECTS SNOWS GOING IN THAT AREA.
SPOTTER REPORTS INDICATE THAT THE SNOW IS VERY FINE AND NOT MUCH
ACCUMULATION TAKING PLACE OVER NORTHERN ALGER AND LUCE COUNTIES.
HOWEVER...WINDS CONTINUE TO BE STRONG THIS AFTERNOON. GUIDANCE SHOW
AS THE HIGH MOVES EAST TONIGHT...PRESSURE GRADIENTS OVER THE AREA
WILL WEAKEN AND WIND WILL TAPER OFF. THIS SHOULD CAUSE THE BLOWING
SNOW TO DIMINISH BY LATE EVENING. RADIATIONAL COOLING WILL CAUSE
TEMPERATURES TO DROP TO -20C. WINDS WILL BE TOO LIGHT TO QUALIFY FOR
WIND CHILL ADVISORY EXCEPT THIS EVENING.
THE LOW OVER THE PACIFIC NORTHWEST WILL SLIDE DOWN THE COAST INTO
NORTHERN CALIFORNIA. AN ACCOMPANYING MID LEVEL TROUGH WILL SHIFT
INTO THE NORTHERN PLAINS...KEEPING ZONAL FLOW ACROSS THE CONUS. THE
LAKE INDUCED SURFACE LOW WILL DEVELOP OVER EASTERN LAKE SUPERIOR ON
MONDAY. A SURFACE LOW WILL SLIDE OUT OF THE CENTRAL PLAINS INTO
NORTHERN MISSOURI ON MONDAY. WITH THE APPROACH OF THE LOW...GUIDANCE
SHOWING A WEAK INSTABILITY AND MOISTURE WORKING NORTH INTO THE
SOUTHERN PART OF THE FORECAST AREA. WILL KEEP A SLIGHT CHANCE GOING
FOR THE SOUTHERN COUNTIES MONDAY AFTERNOON. 850MB TEMPERATURES WILL
KEEP SOME LAKE EFFECT SNOWS GOING INTO THE AFTERNOON.
&&
.LONG TERM (MON NIGHT INTO TUE)...
MON NIGHT INTO TUE...SHRTWV MOVING DOWN THROUGH THE NRN MN AND THE
DAKOTAS IS PROGGED TO MOVE THROUGH UPPER MI TUE MORNING...
MAINTAINING THE COLD AIR OVER THE CWA. THIS SHRTWV WILL ALSO HELP
PROPEL SYSTEM OVER ERN KANSAS NORTHEAST THROUGH LOWER MICHIGAN
DURING THIS PERIOD. KEPT CHANCE POPS GOING FOR MONDAY NIGHT ALONG
THE LAKE MICHIGAN SHORELINE AS GFS STILL INDICATES MID-LVL
FRONTOGENETICAL FORCING AND BOTH GFS/UKMET BRING SOME LIGHT PCPN
INTO THE ERN CWA. OTHERWISE...THE MAIN CONCERN IS LAKE EFFECT SNOW.
WINDS REMAIN MOSTLY WESTERLY MON NIGHT FAVORING PERHAPS A MAIN
CONVERGENT BAND OVER NORTHERN HOUGHTON COUNTY. BY TUE AFTERNOON...
WINDS TURN SLIGHTLY MORE TO THE NW IN THE WAKE OF THE SYSTEM MOVING
THROUGH LOWER MICHIGAN. THIS SLIGHT VEERING OF WINDS SHOULD BRING
LES BACK INTO ONTONAGON COUNTY UP THROUGH THE KEWEENAW SO WILL
MAINTAIN LIKELY POPS FOR THESE AREAS. RAISED TEMPS A FEW MORE
DEGREES MONDAY NIGHT AS CLOUD COVER FROM SYSTEM MOVING THROUGH LOWER
MIDWEST SHOULD KEEP TEMPS UP...ALTHOUGH STILL EXPECT SINGLE DIGITS
BLO ZERO OVER THE WRN INTERIOR. TUE HIGH TEMPS SHOULD BE FAIRLY
SIMILAR TO MON.
TUE NIGHT INTO WED...MODELS SHOW POTENT SHRTWV TROUGH DROPPING SOUTH
THROUGH SOUTH CENTRAL CANADA TUE EVENING INTO THE UPPER GREAT LAKES.
GFS/UKMET/ECMWF PROG 850MB TEMPS TO BE -25 TO -28C ACROSS UPPER MI
BY WED MORNING IN THE WAKE OF THE SHORTWAVE. THE SURFACE COLD FRONT
ASSOCIATED WITH THE TROUGH WILL INTENSIFY THE LOW LEVEL CONVERGENCE
OVER THE KEWEENAW PENINSULA AND THE ERN COUNTIES TUE NIGHT INTO WED.
LIKELY POPS STILL ON TARGET FOR FOR THE NW SNOWBELTS. WITH THE COLD
AIR MOVING IN...HIGH TEMPS AGAIN MAY STRUGGLE TO REACH ABV ZERO
ON WED.
ECMWF/GFS SHOW STRONG WARM ADVECTION ACROSS THE CWA BY THU...WHICH
SHOULD HELP MODERATE TEMPS. THIS WARMING IN TANDEM WITH FLOW BACKING
MORE WRLY SHOULD HELP TAPER LES TO FLURRIES OVER THE KEWEENAW
PENINSULA AND ERN SHORELINE OF THE CWA.
EXPECT DRY CONDITIONS THU NIGHT INTO FRI AS BOTH THE OPERATIONAL GFS
AND ECMWF INDICATE RIDGING OVER THE AREA. AGREEMENT OF THE
OPERATIONAL RUNS WITH THE GFS ENSEMBLE MEAN ALSO INCREASES
CONFIDENCE IN KEEPING THIS PERIOD DRY.
ARRIVAL OF ANOTHER SHORTWAVE TROF FOR THE FRI NIGHT INTO SAT TIME
FRAME PER ECMWF AND GFS WILL WARRANT CHC POPS FOR SNOW ACROSS THE
CWA.
SHIFT TO NWRLY WINDS SAT NIGHT INTO SUN BEHIND FRONTAL SYSTEM SHOULD
KEEP SOME LES AROUND FOR THE NRN AND ERN COUNTIES WHILE ISOLATED
SNOW SHOWERS OR FLURRIES CAN BE EXPECTED FURTHER SOUTH.
&&
.AVIATION (FOR THE 00Z TAF ISSUANCE)...
LES/GENERALLY IFR/LIFR VSBYS AND MVFR/OCNL IFR CIGS WL CONTINUE AT
CMX TNGT BEFORE ARRIVAL OF DRIER AIR SHOWN ON TAMDAR SDNGS FM
DLH/YQT AND SLOWLY BACKING LLVL FLOW CONSPIRE TO AT LEAST DIMINISH
THE LES AND RESULT IN SOME IMPROVEMENT LATE TNGT AND MON MRNG AS LK
INDUCED TROF LOOKS TO SET UP JUST N OF CMX. PASSAGE OF DISTURBANCE
TO THE S WITH VEERING FLOW TO MORE WNW AGAIN LATER ON MON WL LIKELY
SHIFT THE TROF S AGAIN PAST CMX...WITH THE SITE EXPERIENCING
DETERIORATING CONDITIONS LATER ON MON AFTN. SINCE SAW WL BE ON THE S
SIDE OF THE LK INDUCED TROF AND UNDER THE DOMINATION OF DRY...
CONTINENTAL ARCTIC AIR...EXPECT VFR CONDITIONS THERE THRU THE PD.
BUT THERE WL BE AN INCRS IN HI/MID CLDS STARTING LATE TNGT THERE
COINCIDENT WITH THE PASSAGE OF THE DISTURBANCE TO THE S.
&&
.MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)...
WEST TO NORTHWEST WINDS WILL REMAIN IN THE 15 TO 30 KNOT RANGE
TONIGHT AS A TIGHT GRADIENT PERSISTS BETWEEN ARCTIC HIGH PRESSURE
BUILDING SOUTHEAST FROM THE PLAINS AND A LINGERING TROUGH INTO THE
UPPER GREAT LAKES. 15 TO 25 KNOT WESTERLY WINDS ARE EXPECTED MONDAY
INTO EARLY TUESDAY AS A WEAK LOW MOVES THROUGH THE LOWER GREAT LAKES
AND A LOW PRESSURE TROUGH DEVELOPS OVER NORTHERN ONTARIO. A COLD
FRONT WILL MOVE THROUGH TUESDAY NIGHT WITH WINDS VEERING NORTHERLY
AND INCREASING TO 15 TO 30 KNOTS BY WED. HEAVY FREEZING SPRAY WILL
CONTINUE INTO MONDAY DUE TO THE STRONG WINDS AND VERY COLD ARCTIC
AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
MICHIGAN...LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 PM EST MONDAY
     FOR MIZ001-003.
     WIND CHILL ADVISORY UNTIL 11 AM EST /10 AM CST/ MONDAY FOR
     MIZ002-004-005-009>011-084.
     LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST MONDAY
     FOR MIZ002.
     LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 5 AM EST MONDAY
     FOR MIZ006-007.
LAKE SUPERIOR...HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST MONDAY FOR
     LSZ263>267.
LAKE MICHIGAN...HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST MONDAY FOR LMZ248-
     250.
&&
$$
UPDATE...KC
SHORT TERM...DLG
LONG TERM...VOSS
AVIATION...KC
MARINE...DLG
</pre> mi
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MARQUETTE MI
630 PM EST SUN JAN 20 2008
UPDATED FOR AVIATION
.SHORT TERM...
THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR
LAKE EFFECT SNOWS TONIGHT AND THE NEXT SYSTEM APPROACHING FROM THE
SOUTH ON MONDAY.
WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER EASTERN
CANADA. A CLOSED LOW CONTINUES TO DEVELOP OVER IDAHO. WEAK SHORTWAVE
SLIDING DOWN THE LEE OF THE RIDGE ARE OVER WISCONSIN AND EASTERN
U.P. SURFACE ANALYSIS DEPICTS A LARGE HIGH OVER EAST CENTRAL
ILLINOIS WITH THE ACCOMPANYING RIDGE STRETCHING NORTHWEST ACROSS THE
NORTHERN PLAINS INTO ALBERTA. A WEAK SURFACE TROUGH IS OVER EASTERN
LAKE SUPERIOR. AN 850MB THERMAL TROUGH CONTINUES TO SHIFT
EAST...WITH THE LAKE-850MB DELTA-T OF AROUND 28C THIS IS GENERATING
WEAK LOW LEVEL CONVERGENCE AND INSTABILITY. THE LOW LEVEL AIR MASS
IS STILL VERY DRY...WITH THE PRECIPITABLE WATER OF LESS THAN .1 OF
AN INCH. LAKE EFFECT SNOWS CONTINUE OVER THE COUNTIES ADJACENT TO
THE LAKE AND DOWNWIND OF WEST TO NORTHWEST WINDS.
THE LONGWAVE TROUGH WILL SHIFT EAST INTO THE CANADIAN MARITIME. AS
THE CLOSED LOW OVER IDAHO DEEPENS. A RIDGE WILL BE CLIMBING ASHORE
OVER SOUTHWEST CANADA. WEAK SHORTWAVE SLIDING DOWN THE LEE OF THE
RIDGE WILL MOVE INTO EASTERN AND CENTRAL ONTARIO TONIGHT AND SET UP
KIND OF A ZONAL FLOW ACROSS THE CENTRAL CONUS. MID LEVEL WINDS WILL
BACK A LITTLE MORE WEST OVER THE AREA TONIGHT. THE SURFACE HIGH WILL
SHIFT TO EASTERN OHIO RIVER VALLEY. LOW LEVEL CONVERGENCE ALONG THE
LAKE SHORE WILL KEEP SOME LAKE EFFECTS SNOWS GOING IN THAT AREA.
SPOTTER REPORTS INDICATE THAT THE SNOW IS VERY FINE AND NOT MUCH
ACCUMULATION TAKING PLACE OVER NORTHERN ALGER AND LUCE COUNTIES.
HOWEVER...WINDS CONTINUE TO BE STRONG THIS AFTERNOON. GUIDANCE SHOW
AS THE HIGH MOVES EAST TONIGHT...PRESSURE GRADIENTS OVER THE AREA
WILL WEAKEN AND WIND WILL TAPER OFF. THIS SHOULD CAUSE THE BLOWING
SNOW TO DIMINISH BY LATE EVENING. RADIATIONAL COOLING WILL CAUSE
TEMPERATURES TO DROP TO -20C. WINDS WILL BE TOO LIGHT TO QUALIFY FOR
WIND CHILL ADVISORY EXCEPT THIS EVENING.
THE LOW OVER THE PACIFIC NORTHWEST WILL SLIDE DOWN THE COAST INTO
NORTHERN CALIFORNIA. AN ACCOMPANYING MID LEVEL TROUGH WILL SHIFT
INTO THE NORTHERN PLAINS...KEEPING ZONAL FLOW ACROSS THE CONUS. THE
LAKE INDUCED SURFACE LOW WILL DEVELOP OVER EASTERN LAKE SUPERIOR ON
MONDAY. A SURFACE LOW WILL SLIDE OUT OF THE CENTRAL PLAINS INTO
NORTHERN MISSOURI ON MONDAY. WITH THE APPROACH OF THE LOW...GUIDANCE
SHOWING A WEAK INSTABILITY AND MOISTURE WORKING NORTH INTO THE
SOUTHERN PART OF THE FORECAST AREA. WILL KEEP A SLIGHT CHANCE GOING
FOR THE SOUTHERN COUNTIES MONDAY AFTERNOON. 850MB TEMPERATURES WILL
KEEP SOME LAKE EFFECT SNOWS GOING INTO THE AFTERNOON.
&&
.LONG TERM (MON NIGHT INTO TUE)...
MON NIGHT INTO TUE...SHRTWV MOVING DOWN THROUGH THE NRN MN AND THE
DAKOTAS IS PROGGED TO MOVE THROUGH UPPER MI TUE MORNING...
MAINTAINING THE COLD AIR OVER THE CWA. THIS SHRTWV WILL ALSO HELP
PROPEL SYSTEM OVER ERN KANSAS NORTHEAST THROUGH LOWER MICHIGAN
DURING THIS PERIOD. KEPT CHANCE POPS GOING FOR MONDAY NIGHT ALONG
THE LAKE MICHIGAN SHORELINE AS GFS STILL INDICATES MID-LVL
FRONTOGENETICAL FORCING AND BOTH GFS/UKMET BRING SOME LIGHT PCPN
INTO THE ERN CWA. OTHERWISE...THE MAIN CONCERN IS LAKE EFFECT SNOW.
WINDS REMAIN MOSTLY WESTERLY MON NIGHT FAVORING PERHAPS A MAIN
CONVERGENT BAND OVER NORTHERN HOUGHTON COUNTY. BY TUE AFTERNOON...
WINDS TURN SLIGHTLY MORE TO THE NW IN THE WAKE OF THE SYSTEM MOVING
THROUGH LOWER MICHIGAN. THIS SLIGHT VEERING OF WINDS SHOULD BRING
LES BACK INTO ONTONAGON COUNTY UP THROUGH THE KEWEENAW SO WILL
MAINTAIN LIKELY POPS FOR THESE AREAS. RAISED TEMPS A FEW MORE
DEGREES MONDAY NIGHT AS CLOUD COVER FROM SYSTEM MOVING THROUGH LOWER
MIDWEST SHOULD KEEP TEMPS UP...ALTHOUGH STILL EXPECT SINGLE DIGITS
BLO ZERO OVER THE WRN INTERIOR. TUE HIGH TEMPS SHOULD BE FAIRLY
SIMILAR TO MON.
TUE NIGHT INTO WED...MODELS SHOW POTENT SHRTWV TROUGH DROPPING SOUTH
THROUGH SOUTH CENTRAL CANADA TUE EVENING INTO THE UPPER GREAT LAKES.
GFS/UKMET/ECMWF PROG 850MB TEMPS TO BE -25 TO -28C ACROSS UPPER MI
BY WED MORNING IN THE WAKE OF THE SHORTWAVE. THE SURFACE COLD FRONT
ASSOCIATED WITH THE TROUGH WILL INTENSIFY THE LOW LEVEL CONVERGENCE
OVER THE KEWEENAW PENINSULA AND THE ERN COUNTIES TUE NIGHT INTO WED.
LIKELY POPS STILL ON TARGET FOR FOR THE NW SNOWBELTS. WITH THE COLD
AIR MOVING IN...HIGH TEMPS AGAIN MAY STRUGGLE TO REACH ABV ZERO
ON WED.
ECMWF/GFS SHOW STRONG WARM ADVECTION ACROSS THE CWA BY THU...WHICH
SHOULD HELP MODERATE TEMPS. THIS WARMING IN TANDEM WITH FLOW BACKING
MORE WRLY SHOULD HELP TAPER LES TO FLURRIES OVER THE KEWEENAW
PENINSULA AND ERN SHORELINE OF THE CWA.
EXPECT DRY CONDITIONS THU NIGHT INTO FRI AS BOTH THE OPERATIONAL GFS
AND ECMWF INDICATE RIDGING OVER THE AREA. AGREEMENT OF THE
OPERATIONAL RUNS WITH THE GFS ENSEMBLE MEAN ALSO INCREASES
CONFIDENCE IN KEEPING THIS PERIOD DRY.
ARRIVAL OF ANOTHER SHORTWAVE TROF FOR THE FRI NIGHT INTO SAT TIME
FRAME PER ECMWF AND GFS WILL WARRANT CHC POPS FOR SNOW ACROSS THE
CWA.
SHIFT TO NWRLY WINDS SAT NIGHT INTO SUN BEHIND FRONTAL SYSTEM SHOULD
KEEP SOME LES AROUND FOR THE NRN AND ERN COUNTIES WHILE ISOLATED
SNOW SHOWERS OR FLURRIES CAN BE EXPECTED FURTHER SOUTH.
&&
.AVIATION (FOR THE 00Z TAF ISSUANCE)...
LES/GENERALLY IFR/LIFR VSBYS AND MVFR/OCNL IFR CIGS WL CONTINUE AT
CMX TNGT BEFORE ARRIVAL OF DRIER AIR SHOWN ON TAMDAR SDNGS FM
DLH/YQT AND SLOWLY BACKING LLVL FLOW CONSPIRE TO AT LEAST DIMINISH
THE LES AND RESULT IN SOME IMPROVEMENT LATE TNGT AND MON MRNG AS LK
INDUCED TROF LOOKS TO SET UP JUST N OF CMX. PASSAGE OF DISTURBANCE
TO THE S WITH VEERING FLOW TO MORE WNW AGAIN LATER ON MON WL LIKELY
SHIFT THE TROF S AGAIN PAST CMX...WITH THE SITE EXPERIENCING
DETERIORATING CONDITIONS LATER ON MON AFTN. SINCE SAW WL BE ON THE S
SIDE OF THE LK INDUCED TROF AND UNDER THE DOMINATION OF DRY...
CONTINENTAL ARCTIC AIR...EXPECT VFR CONDITIONS THERE THRU THE PD.
BUT THERE WL BE AN INCRS IN HI/MID CLDS STARTING LATE TNGT THERE
COINCIDENT WITH THE PASSAGE OF THE DISTURBANCE TO THE S.
&&
.MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)...
WEST TO NORTHWEST WINDS WILL REMAIN IN THE 15 TO 30 KNOT RANGE
TONIGHT AS A TIGHT GRADIENT PERSISTS BETWEEN ARCTIC HIGH PRESSURE
BUILDING SOUTHEAST FROM THE PLAINS AND A LINGERING TROUGH INTO THE
UPPER GREAT LAKES. 15 TO 25 KNOT WESTERLY WINDS ARE EXPECTED MONDAY
INTO EARLY TUESDAY AS A WEAK LOW MOVES THROUGH THE LOWER GREAT LAKES
AND A LOW PRESSURE TROUGH DEVELOPS OVER NORTHERN ONTARIO. A COLD
FRONT WILL MOVE THROUGH TUESDAY NIGHT WITH WINDS VEERING NORTHERLY
AND INCREASING TO 15 TO 30 KNOTS BY WED. HEAVY FREEZING SPRAY WILL
CONTINUE INTO MONDAY DUE TO THE STRONG WINDS AND VERY COLD ARCTIC
AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
MICHIGAN...LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 PM EST
           MONDAY FOR MIZ001-003.
     WIND CHILL ADVISORY UNTIL 11 AM EST /10 AM CST/ MONDAY FOR
     MIZ002-004-005-009>011-084.
     LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST MONDAY
     FOR MIZ002.
     LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ085.
     LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING FOR MIZ006-
     007.
LAKE SUPERIOR...HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST MONDAY FOR
     LSZ263>267.
LAKE MICHIGAN...HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST MONDAY FOR
     LMZ248-250.
&&
$$
SHORT TERM...DLG
LONG TERM...VOSS
AVIATION...KC
MARINE...DLG
</pre> mi
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
411 PM EST SUN JAN 20 2008
.SHORT TERM...
THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR
LAKE EFFECT SNOWS TONIGHT AND THE NEXT SYSTEM APPROACHING FROM THE
SOUTH ON MONDAY.
WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER EASTERN
CANADA. A CLOSED LOW CONTINUES TO DEVELOP OVER IDAHO. WEAK SHORTWAVE
SLIDING DOWN THE LEE OF THE RIDGE ARE OVER WISCONSIN AND EASTERN
U.P. SURFACE ANALYSIS DEPICTS A LARGE HIGH OVER EAST CENTRAL
ILLINOIS WITH THE ACCOMPANYING RIDGE STRETCHING NORTHWEST ACROSS THE
NORTHERN PLAINS INTO ALBERTA. A WEAK SURFACE TROUGH IS OVER EASTERN
LAKE SUPERIOR. AN 850MB THERMAL TROUGH CONTINUES TO SHIFT
EAST...WITH THE LAKE-850MB DELTA-T OF AROUND 28C THIS IS GENERATING
WEAK LOW LEVEL CONVERGENCE AND INSTABILITY. THE LOW LEVEL AIR MASS
IS STILL VERY DRY...WITH THE PRECIPITABLE WATER OF LESS THAN .1 OF
AN INCH. LAKE EFFECT SNOWS CONTINUE OVER THE COUNTIES ADJACENT TO
THE LAKE AND DOWNWIND OF WEST TO NORTHWEST WINDS.
THE LONGWAVE TROUGH WILL SHIFT EAST INTO THE CANADIAN MARITIME. AS
THE CLOSED LOW OVER IDAHO DEEPENS. A RIDGE WILL BE CLIMBING ASHORE
OVER SOUTHWEST CANADA. WEAK SHORTWAVE SLIDING DOWN THE LEE OF THE
RIDGE WILL MOVE INTO EASTERN AND CENTRAL ONTARIO TONIGHT AND SET UP
KIND OF A ZONAL FLOW ACROSS THE CENTRAL CONUS. MID LEVEL WINDS WILL
BACK A LITTLE MORE WEST OVER THE AREA TONIGHT. THE SURFACE HIGH WILL
SHIFT TO EASTERN OHIO RIVER VALLEY. LOW LEVEL CONVERGENCE ALONG THE
LAKE SHORE WILL KEEP SOME LAKE EFFECTS SNOWS GOING IN THAT AREA.
SPOTTER REPORTS INDICATE THAT THE SNOW IS VERY FINE AND NOT MUCH
ACCUMULATION TAKING PLACE OVER NORTHERN ALGER AND LUCE COUNTIES.
HOWEVER...WINDS CONTINUE TO BE STRONG THIS AFTERNOON. GUIDANCE SHOW
AS THE HIGH MOVES EAST TONIGHT...PRESSURE GRADIENTS OVER THE AREA
WILL WEAKEN AND WIND WILL TAPER OFF. THIS SHOULD CAUSE THE BLOWING
SNOW TO DIMINISH BY LATE EVENING. RADIATIONAL COOLING WILL CAUSE
TEMPERATURES TO DROP TO -20C. WINDS WILL BE TOO LIGHT TO QUALIFY FOR
WIND CHILL ADVISORY EXCEPT THIS EVENING.
THE LOW OVER THE PACIFIC NORTHWEST WILL SLIDE DOWN THE COAST INTO
NORTHERN CALIFORNIA. AN ACCOMPANYING MID LEVEL TROUGH WILL SHIFT
INTO THE NORTHERN PLAINS...KEEPING ZONAL FLOW ACROSS THE CONUS. THE
LAKE INDUCED SURFACE LOW WILL DEVELOP OVER EASTERN LAKE SUPERIOR ON
MONDAY. A SURFACE LOW WILL SLIDE OUT OF THE CENTRAL PLAINS INTO
NORTHERN MISSOURI ON MONDAY. WITH THE APPROACH OF THE LOW...GUIDANCE
SHOWING A WEAK INSTABILITY AND MOISTURE WORKING NORTH INTO THE
SOUTHERN PART OF THE FORECAST AREA. WILL KEEP A SLIGHT CHANCE GOING
FOR THE SOUTHERN COUNTIES MONDAY AFTERNOON. 850MB TEMPERATURES WILL
KEEP SOME LAKE EFFECT SNOWS GOING INTO THE AFTERNOON.
&&
.LONG TERM (MON NIGHT INTO TUE)...
MON NIGHT INTO TUE...SHRTWV MOVING DOWN THROUGH THE NRN MN AND THE
DAKOTAS IS PROGGED TO MOVE THROUGH UPPER MI TUE MORNING...
MAINTAINING THE COLD AIR OVER THE CWA. THIS SHRTWV WILL ALSO HELP
PROPEL SYSTEM OVER ERN KANSAS NORTHEAST THROUGH LOWER MICHIGAN
DURING THIS PERIOD. KEPT CHANCE POPS GOING FOR MONDAY NIGHT ALONG
THE LAKE MICHIGAN SHORELINE AS GFS STILL INDICATES MID-LVL
FRONTOGENETICAL FORCING AND BOTH GFS/UKMET BRING SOME LIGHT PCPN
INTO THE ERN CWA. OTHERWISE...THE MAIN CONCERN IS LAKE EFFECT SNOW.
WINDS REMAIN MOSTLY WESTERLY MON NIGHT FAVORING PERHAPS A MAIN
CONVERGENT BAND OVER NORTHERN HOUGHTON COUNTY. BY TUE AFTERNOON...
WINDS TURN SLIGHTLY MORE TO THE NW IN THE WAKE OF THE SYSTEM MOVING
THROUGH LOWER MICHIGAN. THIS SLIGHT VEERING OF WINDS SHOULD BRING
LES BACK INTO ONTONAGON COUNTY UP THROUGH THE KEWEENAW SO WILL
MAINTAIN LIKELY POPS FOR THESE AREAS. RAISED TEMPS A FEW MORE
DEGREES MONDAY NIGHT AS CLOUD COVER FROM SYSTEM MOVING THROUGH LOWER
MIDWEST SHOULD KEEP TEMPS UP...ALTHOUGH STILL EXPECT SINGLE DIGITS
BLO ZERO OVER THE WRN INTERIOR. TUE HIGH TEMPS SHOULD BE FAIRLY
SIMILAR TO MON.
TUE NIGHT INTO WED...MODELS SHOW POTENT SHRTWV TROUGH DROPPING SOUTH
THROUGH SOUTH CENTRAL CANADA TUE EVENING INTO THE UPPER GREAT LAKES.
GFS/UKMET/ECMWF PROG 850MB TEMPS TO BE -25 TO -28C ACROSS UPPER MI
BY WED MORNING IN THE WAKE OF THE SHORTWAVE. THE SURFACE COLD FRONT
ASSOCIATED WITH THE TROUGH WILL INTENSIFY THE LOW LEVEL CONVERGENCE
OVER THE KEWEENAW PENINSULA AND THE ERN COUNTIES TUE NIGHT INTO WED.
LIKELY POPS STILL ON TARGET FOR FOR THE NW SNOWBELTS. WITH THE COLD
AIR MOVING IN...HIGH TEMPS AGAIN MAY STRUGGLE TO REACH ABV ZERO
ON WED.
ECMWF/GFS SHOW STRONG WARM ADVECTION ACROSS THE CWA BY THU...WHICH
SHOULD HELP MODERATE TEMPS. THIS WARMING IN TANDEM WITH FLOW BACKING
MORE WRLY SHOULD HELP TAPER LES TO FLURRIES OVER THE KEWEENAW
PENINSULA AND ERN SHORELINE OF THE CWA.
EXPECT DRY CONDITIONS THU NIGHT INTO FRI AS BOTH THE OPERATIONAL GFS
AND ECMWF INDICATE RIDGING OVER THE AREA. AGREEMENT OF THE
OPERATIONAL RUNS WITH THE GFS ENSEMBLE MEAN ALSO INCREASES
CONFIDENCE IN KEEPING THIS PERIOD DRY.
ARRIVAL OF ANOTHER SHORTWAVE TROF FOR THE FRI NIGHT INTO SAT TIME
FRAME PER ECMWF AND GFS WILL WARRANT CHC POPS FOR SNOW ACROSS THE
CWA.
SHIFT TO NWRLY WINDS SAT NIGHT INTO SUN BEHIND FRONTAL SYSTEM SHOULD
KEEP SOME LES AROUND FOR THE NRN AND ERN COUNTIES WHILE ISOLATED
SNOW SHOWERS OR FLURRIES CAN BE EXPECTED FURTHER SOUTH.
&&
.AVIATION (FOR THE 18Z TAF ISSUANCE)...
WITH WNW FLOW OF VERY COLD AIR FCST TO PERSIST THRU THIS
EVENING...LITTLE CHANGE IN PREVAILING CONDITIONS WILL OCCUR AT BOTH
SITES DURING THE FCST PERIOD. AT KCMX... LES/IFR TO LIFR VSBYS/IFR
CIGS OCNL MVFR CIGS WL BE THE RULE WITH GUSTY WINDS AT TIMES CAUSING
CONSIDERABLE BLOWING OF THE FINE SNOW FLAKES THAT WILL EFFECTIVELY
REDUCE VSBY. LOOK FOR VFR CONDITIONS AT KSAW FOR THE MOST PART WITH
LESS LK MODIFICATION THERE. SOME BKN SC/HI MVFR CIGS MAY FORM THIS
AFTERNOON WITHIN H85 THERMAL TROF AS WAS THE CASE SAT AFTERNOON.
&&
.MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)...
WEST TO NORTHWEST WINDS WILL REMAIN IN THE 15 TO 30 KNOT RANGE
TONIGHT AS A TIGHT GRADIENT PERSISTS BETWEEN ARCTIC HIGH PRESSURE
BUILDING SOUTHEAST FROM THE PLAINS AND A LINGERING TROUGH INTO THE
UPPER GREAT LAKES. 15 TO 25 KNOT WESTERLY WINDS ARE EXPECTED MONDAY
INTO EARLY TUESDAY AS A WEAK LOW MOVES THROUGH THE LOWER GREAT LAKES
AND A LOW PRESSURE TROUGH DEVELOPS OVER NORTHERN ONTARIO. A COLD
FRONT WILL MOVE THROUGH TUESDAY NIGHT WITH WINDS VEERING NORTHERLY
AND INCREASING TO 15 TO 30 KNOTS BY WED. HEAVY FREEZING SPRAY WILL
CONTINUE INTO MONDAY DUE TO THE STRONG WINDS AND VERY COLD ARCTIC
AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
MICHIGAN...LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 PM EST
           MONDAY FOR MIZ001-003.
     WIND CHILL ADVISORY UNTIL 11 AM EST /10 AM CST/ MONDAY FOR
     MIZ002-004-005-009>011-084.
     LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST MONDAY
     FOR MIZ002.
     LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ085.
     LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING FOR MIZ006-
     007.
LAKE SUPERIOR...HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST MONDAY FOR
     LSZ263>267.
LAKE MICHIGAN...HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST MONDAY FOR
     LMZ248-250.
&&
$$
SHORT TERM...DLG
LONG TERM...VOSS
AVIATION...DLG
MARINE...DLG
</pre> mi
AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE MARQUETTE MI
134 PM EST SUN JAN 20 2008
.SHORT TERM...
THE MAIN CONCERN WITH THIS FORECAST UPDATE IS THE SNOW AND WIND
CHILL READINGS THIS AFTERNOON.
WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER EASTERN
CANADA AND NEW ENGLAND. A CLOSED LOW IS DEVELOPING OVER THE PACIFIC
NORTHWEST AND LARGE RIDGE RUNS THE WEST COAST. WEAK SHORTWAVE
SAILING DOWN THE LEE OF THE RIDGE ARE SWEEPING THE MANITOBA AND
EASTERN U.P. SURFACE ANALYSIS PORTRAYS A LARGE HIGH OVER THE MIDDLE
MISSISSIPPI RIVER VALLEY WITH A RIDGE REACHING NORTHWEST INTO
ALBERTA. A WEAK COLD FRONT OR TROUGH CONTINUES TO STRETCH ACROSS
LAKE SUPERIOR. ANTI-CYCLONIC FLOW EAST OF THE RIDGE IS PULLING THE
COLD AIR OUT OF CENTRAL CANADA INTO THE FORECAST AREA. LOW LEVEL
CONVERGENCE WITH THE FRONTAL SYSTEM...THE COLD AIR...AND LOW LEVEL
MOISTURE BELOW 850MB CONTRIBUTE TO LAKE EFFECT SNOWS OCCURRING OVER
THE AREA AND LOW WIND CHILLS.
THE LONGWAVE TROUGH WILL REMAIN OVER EASTERN NORTH AMERICA THIS
AFTERNOON. THE CLOSED LOW WILL EDGE INTO WEST CENTRAL IDAHO. THE
MISSISSIPPI RIVER VALLEY HIGH WILL START TO SLIP INTO WESTERN OHIO
RIVER VALLEY KEEPING THE RIDGE OVER MINNESOTA...EASTERN NORTH DAKOTA
AND SOUTHERN SASKATCHEWAN. THUS ONLY MINOR CHANGES IN THE SYNOPIC
PATTERN EXPECTED. 850MB TEMPERATURES AROUND -25C WILL CONTINUE OVER
THE AREA. THE BEST SNOW GROWTH AREA CONTINUES TO BE IN THE LOW
LEVEL. WINDS ARE GENERALLY IN THE 5 TO 15 MPH RANGE. UNDER MOSTLY
CLEAR SKIES...TEMPERATURES ARE COMING UP. MOST ALL THE REPORTING
STATION THROUGH UPPER MICHIGAN HAVE MODERATE WIND CHILLS...THUS WILL
CANCEL ALL THE WIND CHILL ADVISORIES EXCEPT FOR GOGEBIC COUNTY.
.LONG TERM...
TONIGHT...UPPER FLOW TURNS MORE WESTERLY AS THE SHRTWV OVER CENTRAL
SASKATCHEWAN DROPS DOWN INTO NORTH DAKOTA. AT THE SURFACE...THIS
ALLOWS FOR THE HIGH PRESSURE RIDGE THAT HAS BEEN OVER THE DAKOTAS
INTO MN TO START BUILDING INTO THE CWA. THUS...LOW LEVEL WIND FLOW
SHOULD BACK TOWARDS THE SOUTHWEST...ENHANCED BY LAND BREEZES. WITH
THE ADJUSTMENT TO THE WIND FIELD...CONVERGENCE AREAS SHIFT
NORTH...MORE OVER THE KEWEENAW AND TOWARDS WAWA ONTARIO.
THEREFORE...LAKE EFFECT SNOWS THAT HAVE BEEN STUCK OVER THE EASTERN
CWA WILL MOSTLY END TOWARDS SUNRISE. HAVE DECLINED TO EXTEND THE
WARNINGS FOR THE EAST PAST 00Z AS IT LOOKS MORE LIKE AN ADVISORY
SCENARIO FOR TONIGHT. DID EXTEND ADVISORIES FOR THE WESTERN CWA
THROUGH TONIGHT...THOUGH...GIVEN THE BREEZY CONDITIONS AND
PERSISTENT FINE SNOWFLAKES. WITH THE SURFACE FLOW BACKING TO THE
SOUTHWEST AND DIMINISHING WIND SPEEDS INLAND...READINGS MAY GET
QUITE COLD. COOP GUIDANCE OF -20F FOR CHAMPION SEEMS LIKELY...
ESPECIALLY GIVEN READINGS UPSTREAM IN MN. INCOMING HIGH CLOUDS LATE
THROUGH THE UPPER FLOW MAY HELP KEEP TEMPS FROM DROPPING TOO MUCH
LOWER. AS FAR AS WIND CHILLS...COLDEST AREAS WILL NOT MEET THE WIND
CRITERIA (LIKELY CALM WINDS AT THE COLDEST AREAS)...THUS AM HESITANT
AT THIS POINT TO EXTEND GOING WIND CHILL ADVISORIES.
MONDAY...SHRTWV DROPPING THROUGH NORTH DAKOTA TONIGHT MOVES INTO THE
GRAND FORKS AREA BY 00Z. MEANWHILE...A SHRTWV CURRENTLY LOCATED ON
THE WEST SIDE OF THE PACIFIC NW UPPER TROUGH IS SHOWN TO MOVE
EASTWARD ACROSS THE ROCKIES INTO KANSAS BY 00Z. IN RESPONSE TO THIS
SECOND SHRTWV...LOW PRESSURE DEVELOPS NEAR KANSAS CITY. MID-LEVEL
FRONTOGENESIS/ISENTROPIC LIFT NORTH AND NORTHEAST OF THIS LOW
COMBINED WITH A GULF OF MEXICO MOISTURE CONNECTION SHOULD SPREAD
LIGHT SNOW INTO WISCONSIN THROUGH THE DAY. IT IS POSSIBLE THAT SOME
OF THE SNOW COULD ALSO SPREAD INTO THE SOUTHERN U.P....WITH THE DRY
AIRMASS IN PLACE THE MAIN PROBLEM OF SPREADING THE SNOW NORTHWARD.
THE ONLY OTHER ITEM OF CONCERN IS THE LAKE EFFECT SNOW ACROSS THE
KEWEENAW PENINSULA. THE NAM/GFS/LOCAL WRF-ARW DEPICT A DECENT LOW
LEVEL CONVERGENCE ZONE SETTING UP THERE...IN ADDITION TO A WARMER
SOUNDING PROFILE FAVORING MORE DENDRITE PRODUCTION. THUS...SNOW TO
WATER RATIOS SHOULD GO UP. SINCE PLENTY OF WIND STILL REMAINS IN THE
BOUNDARY LAYER...AND FORECAST SNOWFALL AMOUNTS OF 3-5 INCHES...HAVE
DECIDED TO EXTEND THE ADVISORY FOR THE KEWEENAW PENINSULA TO 00Z
TUE. AS MENTIONED EARLIER...WARMER AIR MOVES INTO THE CWA...WHICH
SHOULD BRING TEMPS UP 5 TO 8 DEGREES MORE THAN THOSE TODAY.
STILL...THE VALUES REMAIN 10 TO 15 DEGREES BELOW NORMAL.
MON NIGHT INTO TUE...SHRTWV OVER NW MN IS PROGGED TO MOVE THROUGH
UPPER MI TUE MORNING...MAINTAINING COLD AIR OVER THE CWA. THIS
SHRTWV WILL ALSO HELP KEEP THE SYSTEM OVER KANSAS CITY...WHICH IS
SHOWN TO MOVE UP THROUGH LOWER MICHIGAN DURING THIS PERIOD...FAIRLY
PROGRESSIVE. HAVE KEPT CHANCE POPS GOING FOR MONDAY NIGHT ALONG THE
LAKE MICHIGAN SHORELINE FOR ANY FRONTOGENETICAL PCPN THAT MAKES IT
INTO THE CWA. OTHERWISE...THE MAIN CONCERN IS LAKE EFFECT SNOW.
WINDS REMAIN MOSTLY WESTERLY MON NIGHT...FAVORING MAINLY THE WESTERN
U.P.. HARD TO TELL IF THERE WILL BE ANY MAIN CONVERGENT BAND AT THIS
POINT...BUT IF ANYWHERE WOULD PROBABLY BE SITUATED IN NORTHERN
HOUGHTON COUNTY. FOR TUE...WINDS TURN SLIGHTLY MORE TO THE NW IN THE
WAKE OF THE SYSTEM MOVING THROUGH LOWER MICHIGAN. HOWEVER...IT NEVER
LOOKS LIKE THEY WILL FULLY GO NW AS MODELS SHOW ANOTHER SHRTWV
TROUGH DROPPING SOUTH THROUGH SOUTH CENTRAL CANADA...WHICH WOULD
HELP TO KEEP THE FLOW BACKED MORE. THUS...THE BEST AREA FOR LAKE
EFFECT ON TUE REMAINS FROM ONTONAGON COUNTY THROUGH THE
KEWEENAW...AND HAVE RAISED POPS TO LIKELY. RAISED TEMPS A FEW
DEGREES MONDAY NIGHT WITH CLOUD COVER FROM THE SYSTEM KEEPING TEMPS
UP. TUES TEMPS LOOK FAIRLY SIMILAR TO MON.
TUE NIGHT INTO WED...SHRTWV TROUGH DROPPING SOUTH THROUGH SOUTH
CENTRAL CANADA LOOKS FAIRLY POTENT...AND THE GFS/UKMET/ECMWF REFLECT
THIS IN 850MB TEMP FIELDS...SHOWING ANOTHER BATCH OF -25 TO -28C AIR
DROPPING INTO UPPER MI BY WED MORNING. THE SURFACE COLD FRONT
ASSOCIATED WITH THE TROUGH SHOULD INTENSIFY THE LOW LEVEL
CONVERGENCE OVER THE KEWEENAW PENINSULA TUE NIGHT...WHICH WILL THEN
DROP SOUTH THROUGH THE CWA ON WED. THUS...LIKELY POPS SEEM
REASONABLE AT LEAST FOR THE NW SNOWBELTS. WITH THE COLD AIR MOVING
IN ON WED...COOLED HIGH TEMPS A FEW DEGREES.
BEYOND WED...ECMWF/GFS SHOW STRONG WARM ADVECTION ACROSS THE CWA ON
THU...WHICH SHOULD HELP MODERATE TEMPS. NO CHANGES MADE TO THE
FORECAST AFTER WED.
&&
.AVIATION (FOR THE 18Z TAF ISSUANCE)...
WITH WNW FLOW OF VERY COLD AIR FCST TO PERSIST THRU THIS
EVENING...LITTLE CHANGE IN PREVAILING CONDITIONS WILL OCCUR AT BOTH
SITES DURING THE FCST PERIOD. AT KCMX... LES/IFR TO LIFR VSBYS/IFR
CIGS OCNL MVFR CIGS WL BE THE RULE WITH GUSTY WINDS AT TIMES CAUSING
CONSIDERABLE BLOWING OF THE FINE SNOW FLAKES THAT WILL EFFECTIVELY
REDUCE VSBY. LOOK FOR VFR CONDITIONS AT KSAW FOR THE MOST PART WITH
LESS LK MODIFICATION THERE. SOME BKN SC/HI MVFR CIGS MAY FORM THIS
AFTERNOON WITHIN H85 THERMAL TROF AS WAS THE CASE SAT AFTERNOON.
&&
.MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)...
NW WINDS WILL REMAIN IN THE 15 TO 30 KNOT RANGE TODAY AND TONIGHT AS
A TIGHT GRADIENT PERSISTS BETWEEN ARCTIC HIGH PRESSURE BUILDING
SOUTHEAST FROM THE PLAINS AND A LINGERING TROUGH INTO THE UPPER
GREAT LAKES. 15 TO 25 KNOT WESTERLY WINDS ARE EXPECTED MONDAY INTO
EARLY TUESDAY AS A WEAK LOW MOVES THROUGH THE CENTRAL GREAT LAKES
AND A LOW PRESSURE TROUGH DEVELOPS OVER NORTHERN ONTARIO. A COLD
FRONT WILL MOVE THROUGH TUESDAY NIGHT WITH WINDS VEERING NORTHERLY
AND INCREASING TO 15 TO 30 KNOTS BY WED. HEAVY FREEZING SPRAY WILL
CONTINUE INTO MONDAY DUE TO THE STRONG WINDS AND VERY COLD ARCTIC
AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
MICHIGAN...
  WIND CHILL ADVISORY UNTIL NOON CST/ THIS AFTERNOON FOR MIZ002.
  LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING MIZ006-007.
  LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ085.
  LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 PM EST
    MONDAY FOR MIZ001-003.
  LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST MONDAY
    FOR MIZ002.
LAKE SUPERIOR...
  HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST MONDAY LSZ162-263>267.
LAKE MICHIGAN...
  HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST MONDAY FOR LMZ248-250.
&&
$$
SHORT TERM...DLG
LONG TERM...AJ
AVIATION...DLG
MARINE...JLB
</pre> mi
AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE MARQUETTE MI
650 AM EST SUN JAN 20 2008
UPDATED FOR 12Z TAF DISCUSSION
.SYNOPSIS...
09Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED TROUGHING
ACROSS MUCH OF NORTH AMERICA...WHICH IS ACTUALLY MADE UP OF TWO
SEPARATES TROUGH. ONE TROUGH CAN BE SEEN DROPPING SOUTH THROUGH
BRITISH COLUMBIA AND THE PACIFIC NW...WHILE THE MAIN LONGWAVE TROUGH
STRETCHES FROM HUDSON BAY SOUTHWARD THROUGH THE GREAT LAKES AND INTO
THE OHIO VALLEY. WITHIN THE MAIN LONGWAVE TROUGH...SHRTWVS TO NOTE
ARE OVER WESTERN LAKE SUPERIOR AND CENTRAL SASKATCHEWAN. SHRTWV OVER
WESTERN LAKE SUPERIOR DOES HAVE SOME MOISTURE WITH IT...AS NOTED BY
NEARLY SATURATED CONDITIONS BETWEEN 900-600MB ON THE 00Z CWPL
SOUNDING. HOWEVER...GIVEN THAT THE ENTIRE SOUNDING IS BELOW
-25C...THE PRECIPITABLE WATER IS QUITE LOW AT 0.05 INCH. WOULD
ASSUME THAT THIS MOISTURE IS PROVIDING SOME LAKE ENHANCEMENT TO THE
ONGOING LAKE EFFECT...BUT GIVEN HOW COLD THE AIRMASS IS...SNOWFLAKE
SIZE IS STILL PROBABLY SMALL...ESPECIALLY OVER THE WESTERN U.P. WITH
THE SHORTER FETCH NOT ALLOWING FOR AS MUCH WARMING. THE AIR THAT IS
COMING IN ON THE WEST SIDE OF THE SHRTWV IS REPRESENTED BY THE 00Z
INL SOUNDING...WHICH IS ALSO ALL BELOW -25C BUT WITH DEWPOINT
DEPRESSIONS OF 5-10C FROM THE SFC TO 300MB. THIS DRIER AIR COMBINED
WITH CLEAR SKIES...ALONG WITH A RIDGE OF HIGH PRESSURE AT THE
SURFACE...HAS ALLOWED TEMPS TO FALL OVER MN INTO THE -20S F. THANKS
TO SOME FLOW OFF LAKE SUPERIOR...TEMPS ARE ONLY IN THE SINGLE DIGITS
TO TEENS BELOW ZERO...EXCLUDING THOSE IMMEDIATELY NEAR THE SHORE
THAT HAVE NW WINDS. NEXT NEAREST SYNOPTIC CLOUDS ARE OVER SOUTH
DAKOTA ASSOCIATED WITH THE TROUGH DROPPING THROUGH THE PACIFIC NW.
&&
.DISCUSSION...
MAIN FORECAST CONCERN IS MOSTLY LAKE EFFECT SNOW THROUGH WEDNESDAY.
TODAY...BASICALLY A REPEAT OF YESTERDAY...WITH ARCTIC AIR REMAINING
IN PLACE WITH NW UPPER FLOW ALOFT. THIS UPPER FLOW DOES BACK A BIT
MORE WESTERLY BY THE END OF THE DAY...SO SOME SLIGHT 850MB WARMING
IS SHOWN TO OCCUR. STILL...READINGS REMAIN AT OR BELOW -23C WITH
GENERAL LOW LEVEL WNW FLOW. LOW LEVEL CONVERGENCE AREAS ARE
INDICATED TO REMAIN IN PLACE OVER ONTONAGON INTO NORTHERN HOUGHTON
COUNTIES...AND OVER EASTERN ALGER INTO NORTHERN LUCE COUNTIES DUE TO
LAKE INDUCED TROUGHING. HOWEVER...STRONGEST LOW LEVEL CONVERGENCE IS
DEPICTED IN THE EASTERN CWA...AND WITH THE LONGER FETCH OFF LAKE
SUPERIOR MAXIMIZING THE MOST WARMING AND THUS BETTER SNOW CRYSTAL
TYPE (NOTED BY SOUNDINGS DEPICTING A CHANCE FOR SOME DENDRITES TO
FORM)...THIS AREA SHOULD PICK UP THE MOST SNOW OUT OF THE CWA. IN
THIS AREA...WOULD EXPECT SNOW TO WATER RATIOS SOMEWHERE NEAR 25 TO
1...COMPARED TO 20 TO 1 OR LESS IN THE WESTERN CWA. GOING WARNINGS
FOR THE EASTERN CWA LOOK GOOD. HAVE DECIDED TO EXTEND ADVISORIES
OVER THE WESTERN CWA GIVEN BREEZY CONDITIONS EXPECTED THERE ALONG
WITH PERSISTENT FINE SNOWFLAKES. OVER THE REST OF THE CWA...ANOTHER
DRY COLD DAY WITH SOME DIURNAL STRATOCUMULUS IS EXPECTED.
TONIGHT...UPPER FLOW TURNS MORE WESTERLY AS THE SHRTWV OVER CENTRAL
SASKATCHEWAN DROPS DOWN INTO NORTH DAKOTA. AT THE SURFACE...THIS
ALLOWS FOR THE HIGH PRESSURE RIDGE THAT HAS BEEN OVER THE DAKOTAS
INTO MN TO START BUILDING INTO THE CWA. THUS...LOW LEVEL WIND FLOW
SHOULD BACK TOWARDS THE SOUTHWEST...ENHANCED BY LAND BREEZES. WITH
THE ADJUSTMENT TO THE WIND FIELD...CONVERGENCE AREAS SHIFT
NORTH...MORE OVER THE KEWEENAW AND TOWARDS WAWA ONTARIO.
THEREFORE...LAKE EFFECT SNOWS THAT HAVE BEEN STUCK OVER THE EASTERN
CWA WILL MOSTLY END TOWARDS SUNRISE. HAVE DECLINED TO EXTEND THE
WARNINGS FOR THE EAST PAST 00Z AS IT LOOKS MORE LIKE AN ADVISORY
SCENARIO FOR TONIGHT. DID EXTEND ADVISORIES FOR THE WESTERN CWA
THROUGH TONIGHT...THOUGH...GIVEN THE BREEZY CONDITIONS AND
PERSISTENT FINE SNOWFLAKES. WITH THE SURFACE FLOW BACKING TO THE
SOUTHWEST AND DIMINISHING WIND SPEEDS INLAND...READINGS MAY GET
QUITE COLD. COOP GUIDANCE OF -20F FOR CHAMPION SEEMS LIKELY...
ESPECIALLY GIVEN READINGS UPSTREAM IN MN. INCOMING HIGH CLOUDS LATE
THROUGH THE UPPER FLOW MAY HELP KEEP TEMPS FROM DROPPING TOO MUCH
LOWER. AS FAR AS WIND CHILLS...COLDEST AREAS WILL NOT MEET THE WIND
CRITERIA (LIKELY CALM WINDS AT THE COLDEST AREAS)...THUS AM HESITANT
AT THIS POINT TO EXTEND GOING WIND CHILL ADVISORIES.
MONDAY...SHRTWV DROPPING THROUGH NORTH DAKOTA TONIGHT MOVES INTO THE
GRAND FORKS AREA BY 00Z. MEANWHILE...A SHRTWV CURRENTLY LOCATED ON
THE WEST SIDE OF THE PACIFIC NW UPPER TROUGH IS SHOWN TO MOVE
EASTWARD ACROSS THE ROCKIES INTO KANSAS BY 00Z. IN RESPONSE TO THIS
SECOND SHRTWV...LOW PRESSURE DEVELOPS NEAR KANSAS CITY. MID-LEVEL
FRONTOGENESIS/ISENTROPIC LIFT NORTH AND NORTHEAST OF THIS LOW
COMBINED WITH A GULF OF MEXICO MOISTURE CONNECTION SHOULD SPREAD
LIGHT SNOW INTO WISCONSIN THROUGH THE DAY. IT IS POSSIBLE THAT SOME
OF THE SNOW COULD ALSO SPREAD INTO THE SOUTHERN U.P....WITH THE DRY
AIRMASS IN PLACE THE MAIN PROBLEM OF SPREADING THE SNOW NORTHWARD.
THE ONLY OTHER ITEM OF CONCERN IS THE LAKE EFFECT SNOW ACROSS THE
KEWEENAW PENINSULA. THE NAM/GFS/LOCAL WRF-ARW DEPICT A DECENT LOW
LEVEL CONVERGENCE ZONE SETTING UP THERE...IN ADDITION TO A WARMER
SOUNDING PROFILE FAVORING MORE DENDRITE PRODUCTION. THUS...SNOW TO
WATER RATIOS SHOULD GO UP. SINCE PLENTY OF WIND STILL REMAINS IN THE
BOUNDARY LAYER...AND FORECAST SNOWFALL AMOUNTS OF 3-5 INCHES...HAVE
DECIDED TO EXTEND THE ADVISORY FOR THE KEWEENAW PENINSULA TO 00Z
TUE. AS MENTIONED EARLIER...WARMER AIR MOVES INTO THE CWA...WHICH
SHOULD BRING TEMPS UP 5 TO 8 DEGREES MORE THAN THOSE TODAY.
STILL...THE VALUES REMAIN 10 TO 15 DEGREES BELOW NORMAL.
MON NIGHT INTO TUE...SHRTWV OVER NW MN IS PROGGED TO MOVE THROUGH
UPPER MI TUE MORNING...MAINTAINING COLD AIR OVER THE CWA. THIS
SHRTWV WILL ALSO HELP KEEP THE SYSTEM OVER KANSAS CITY...WHICH IS
SHOWN TO MOVE UP THROUGH LOWER MICHIGAN DURING THIS PERIOD...FAIRLY
PROGRESSIVE. HAVE KEPT CHANCE POPS GOING FOR MONDAY NIGHT ALONG THE
LAKE MICHIGAN SHORELINE FOR ANY FRONTOGENETICAL PCPN THAT MAKES IT
INTO THE CWA. OTHERWISE...THE MAIN CONCERN IS LAKE EFFECT SNOW.
WINDS REMAIN MOSTLY WESTERLY MON NIGHT...FAVORING MAINLY THE WESTERN
U.P.. HARD TO TELL IF THERE WILL BE ANY MAIN CONVERGENT BAND AT THIS
POINT...BUT IF ANYWHERE WOULD PROBABLY BE SITUATED IN NORTHERN
HOUGHTON COUNTY. FOR TUE...WINDS TURN SLIGHTLY MORE TO THE NW IN THE
WAKE OF THE SYSTEM MOVING THROUGH LOWER MICHIGAN. HOWEVER...IT NEVER
LOOKS LIKE THEY WILL FULLY GO NW AS MODELS SHOW ANOTHER SHRTWV
TROUGH DROPPING SOUTH THROUGH SOUTH CENTRAL CANADA...WHICH WOULD
HELP TO KEEP THE FLOW BACKED MORE. THUS...THE BEST AREA FOR LAKE
EFFECT ON TUE REMAINS FROM ONTONAGON COUNTY THROUGH THE
KEWEENAW...AND HAVE RAISED POPS TO LIKELY. RAISED TEMPS A FEW
DEGREES MONDAY NIGHT WITH CLOUD COVER FROM THE SYSTEM KEEPING TEMPS
UP. TUES TEMPS LOOK FAIRLY SIMILAR TO MON.
TUE NIGHT INTO WED...SHRTWV TROUGH DROPPING SOUTH THROUGH SOUTH
CENTRAL CANADA LOOKS FAIRLY POTENT...AND THE GFS/UKMET/ECMWF REFLECT
THIS IN 850MB TEMP FIELDS...SHOWING ANOTHER BATCH OF -25 TO -28C AIR
DROPPING INTO UPPER MI BY WED MORNING. THE SURFACE COLD FRONT
ASSOCIATED WITH THE TROUGH SHOULD INTENSIFY THE LOW LEVEL
CONVERGENCE OVER THE KEWEENAW PENINSULA TUE NIGHT...WHICH WILL THEN
DROP SOUTH THROUGH THE CWA ON WED. THUS...LIKELY POPS SEEM
REASONABLE AT LEAST FOR THE NW SNOWBELTS. WITH THE COLD AIR MOVING
IN ON WED...COOLED HIGH TEMPS A FEW DEGREES.
BEYOND WED...ECMWF/GFS SHOW STRONG WARM ADVECTION ACROSS THE CWA ON
THU...WHICH SHOULD HELP MODERATE TEMPS. NO CHANGES MADE TO THE
FORECAST AFTER WED.
&&
.AVIATION (FOR THE 12Z TAF ISSUANCE)...
WITH WNW FLOW OF VERY COLD AIR FCST TO PERSIST THRU THIS EVENING...
EXPECT LITTLE CHANGE IN PREVAILING CONDITIONS AT BOTH SITES DURING
THE FCST PERIOD. AT KCMX... LES/IFR TO LIFR VSBYS/IFR CIGS OCNL MVFR
CIGS WL BE THE RULE WITH GUSTY WINDS AT TIMES CAUSING CONSIDERABLE
BLOWING OF THE FINE SNOW FLAKES THAT WILL EFFECTIVELY REDUCE VSBY.
LOOK FOR VFR CONDITIONS AT KSAW FOR THE MOST PART WITH LESS LK
MODIFICATION THERE. SOME BKN SC/HI MVFR CIGS MAY FORM THIS AFTERNOON
WITHIN H85 THERMAL TROF AS WAS THE CASE SAT AFTERNOON.
&&
.MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)...
NW WINDS WILL REMAIN IN THE 15 TO 30 KNOT RANGE TODAY AND TONIGHT AS
A TIGHT GRADIENT PERSISTS BETWEEN ARCTIC HIGH PRESSURE BUILDING
SOUTHEAST FROM THE PLAINS AND A LINGERING TROUGH INTO THE UPPER
GREAT LAKES. 15 TO 25 KNOT WESTERLY WINDS ARE EXPECTED MONDAY INTO
EARLY TUESDAY AS A WEAK LOW MOVES THROUGH THE CENTRAL GREAT LAKES
AND A LOW PRESSURE TROUGH DEVELOPS OVER NORTHERN ONTARIO. A COLD
FRONT WILL MOVE THROUGH TUESDAY NIGHT WITH WINDS VEERING NORTHERLY
AND INCREASING TO 15 TO 30 KNOTS BY WED. HEAVY FREEZING SPRAY WILL
CONTINUE INTO MONDAY DUE TO THE STRONG WINDS AND VERY COLD ARCTIC
AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
MICHIGAN...
  WIND CHILL ADVISORY UNTIL 1 PM EST /NOON CST/ THIS AFTERNOON FOR
    MIZ002-004-005-009>014-084.
  LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING MIZ006-007.
  LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ085.
  LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 PM EST
    MONDAY FOR MIZ001-003.
  LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST MONDAY
    FOR MIZ002.
LAKE SUPERIOR...
  HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST MONDAY LSZ162-263>267.
LAKE MICHIGAN...
  HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST MONDAY FOR LMZ248-250.
&&
$$
SYNOPSIS/DISCUSSION...AJ
AVIATION/MARINE...JLB
</pre> mi
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
419 AM EST SUN JAN 20 2008
.SYNOPSIS...
09Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED TROUGHING
ACROSS MUCH OF NORTH AMERICA...WHICH IS ACTUALLY MADE UP OF TWO
SEPARATES TROUGH. ONE TROUGH CAN BE SEEN DROPPING SOUTH THROUGH
BRITISH COLUMBIA AND THE PACIFIC NW...WHILE THE MAIN LONGWAVE TROUGH
STRETCHES FROM HUDSON BAY SOUTHWARD THROUGH THE GREAT LAKES AND INTO
THE OHIO VALLEY. WITHIN THE MAIN LONGWAVE TROUGH...SHRTWVS TO NOTE
ARE OVER WESTERN LAKE SUPERIOR AND CENTRAL SASKATCHEWAN. SHRTWV OVER
WESTERN LAKE SUPERIOR DOES HAVE SOME MOISTURE WITH IT...AS NOTED BY
NEARLY SATURATED CONDITIONS BETWEEN 900-600MB ON THE 00Z CWPL
SOUNDING. HOWEVER...GIVEN THAT THE ENTIRE SOUNDING IS BELOW
-25C...THE PRECIPITABLE WATER IS QUITE LOW AT 0.05 INCH. WOULD
ASSUME THAT THIS MOISTURE IS PROVIDING SOME LAKE ENHANCEMENT TO THE
ONGOING LAKE EFFECT...BUT GIVEN HOW COLD THE AIRMASS IS...SNOWFLAKE
SIZE IS STILL PROBABLY SMALL...ESPECIALLY OVER THE WESTERN U.P. WITH
THE SHORTER FETCH NOT ALLOWING FOR AS MUCH WARMING. THE AIR THAT IS
COMING IN ON THE WEST SIDE OF THE SHRTWV IS REPRESENTED BY THE 00Z
INL SOUNDING...WHICH IS ALSO ALL BELOW -25C BUT WITH DEWPOINT
DEPRESSIONS OF 5-10C FROM THE SFC TO 300MB. THIS DRIER AIR COMBINED
WITH CLEAR SKIES...ALONG WITH A RIDGE OF HIGH PRESSURE AT THE
SURFACE...HAS ALLOWED TEMPS TO FALL OVER MN INTO THE -20S F. THANKS
TO SOME FLOW OFF LAKE SUPERIOR...TEMPS ARE ONLY IN THE SINGLE DIGITS
TO TEENS BELOW ZERO...EXCLUDING THOSE IMMEDIATELY NEAR THE SHORE
THAT HAVE NW WINDS. NEXT NEAREST SYNOPTIC CLOUDS ARE OVER SOUTH
DAKOTA ASSOCIATED WITH THE TROUGH DROPPING THROUGH THE PACIFIC NW.
&&
.DISCUSSION...
MAIN FORECAST CONCERN IS MOSTLY LAKE EFFECT SNOW THROUGH WEDNESDAY.
TODAY...BASICALLY A REPEAT OF YESTERDAY...WITH ARCTIC AIR REMAINING
IN PLACE WITH NW UPPER FLOW ALOFT. THIS UPPER FLOW DOES BACK A BIT
MORE WESTERLY BY THE END OF THE DAY...SO SOME SLIGHT 850MB WARMING
IS SHOWN TO OCCUR. STILL...READINGS REMAIN AT OR BELOW -23C WITH
GENERAL LOW LEVEL WNW FLOW. LOW LEVEL CONVERGENCE AREAS ARE
INDICATED TO REMAIN IN PLACE OVER ONTONAGON INTO NORTHERN HOUGHTON
COUNTIES...AND OVER EASTERN ALGER INTO NORTHERN LUCE COUNTIES DUE TO
LAKE INDUCED TROUGHING. HOWEVER...STRONGEST LOW LEVEL CONVERGENCE IS
DEPICTED IN THE EASTERN CWA...AND WITH THE LONGER FETCH OFF LAKE
SUPERIOR MAXIMIZING THE MOST WARMING AND THUS BETTER SNOW CRYSTAL
TYPE (NOTED BY SOUNDINGS DEPICTING A CHANCE FOR SOME DENDRITES TO
FORM)...THIS AREA SHOULD PICK UP THE MOST SNOW OUT OF THE CWA. IN
THIS AREA...WOULD EXPECT SNOW TO WATER RATIOS SOMEWHERE NEAR 25 TO
1...COMPARED TO 20 TO 1 OR LESS IN THE WESTERN CWA. GOING WARNINGS
FOR THE EASTERN CWA LOOK GOOD. HAVE DECIDED TO EXTEND ADVISORIES
OVER THE WESTERN CWA GIVEN BREEZY CONDITIONS EXPECTED THERE ALONG
WITH PERSISTENT FINE SNOWFLAKES. OVER THE REST OF THE CWA...ANOTHER
DRY COLD DAY WITH SOME DIURNAL STRATOCUMULUS IS EXPECTED.
TONIGHT...UPPER FLOW TURNS MORE WESTERLY AS THE SHRTWV OVER CENTRAL
SASKATCHEWAN DROPS DOWN INTO NORTH DAKOTA. AT THE SURFACE...THIS
ALLOWS FOR THE HIGH PRESSURE RIDGE THAT HAS BEEN OVER THE DAKOTAS
INTO MN TO START BUILDING INTO THE CWA. THUS...LOW LEVEL WIND FLOW
SHOULD BACK TOWARDS THE SOUTHWEST...ENHANCED BY LAND BREEZES. WITH
THE ADJUSTMENT TO THE WIND FIELD...CONVERGENCE AREAS SHIFT
NORTH...MORE OVER THE KEWEENAW AND TOWARDS WAWA ONTARIO.
THEREFORE...LAKE EFFECT SNOWS THAT HAVE BEEN STUCK OVER THE EASTERN
CWA WILL MOSTLY END TOWARDS SUNRISE. HAVE DECLINED TO EXTEND THE
WARNINGS FOR THE EAST PAST 00Z AS IT LOOKS MORE LIKE AN ADVISORY
SCENARIO FOR TONIGHT. DID EXTEND ADVISORIES FOR THE WESTERN CWA
THROUGH TONIGHT...THOUGH...GIVEN THE BREEZY CONDITIONS AND
PERSISTENT FINE SNOWFLAKES. WITH THE SURFACE FLOW BACKING TO THE
SOUTHWEST AND DIMINISHING WIND SPEEDS INLAND...READINGS MAY GET
QUITE COLD. COOP GUIDANCE OF -20F FOR CHAMPION SEEMS LIKELY...
ESPECIALLY GIVEN READINGS UPSTREAM IN MN. INCOMING HIGH CLOUDS LATE
THROUGH THE UPPER FLOW MAY HELP KEEP TEMPS FROM DROPPING TOO MUCH
LOWER. AS FAR AS WIND CHILLS...COLDEST AREAS WILL NOT MEET THE WIND
CRITERIA (LIKELY CALM WINDS AT THE COLDEST AREAS)...THUS AM HESITANT
AT THIS POINT TO EXTEND GOING WIND CHILL ADVISORIES.
MONDAY...SHRTWV DROPPING THROUGH NORTH DAKOTA TONIGHT MOVES INTO THE
GRAND FORKS AREA BY 00Z. MEANWHILE...A SHRTWV CURRENTLY LOCATED ON
THE WEST SIDE OF THE PACIFIC NW UPPER TROUGH IS SHOWN TO MOVE
EASTWARD ACROSS THE ROCKIES INTO KANSAS BY 00Z. IN RESPONSE TO THIS
SECOND SHRTWV...LOW PRESSURE DEVELOPS NEAR KANSAS CITY. MID-LEVEL
FRONTOGENESIS/ISENTROPIC LIFT NORTH AND NORTHEAST OF THIS LOW
COMBINED WITH A GULF OF MEXICO MOISTURE CONNECTION SHOULD SPREAD
LIGHT SNOW INTO WISCONSIN THROUGH THE DAY. IT IS POSSIBLE THAT SOME
OF THE SNOW COULD ALSO SPREAD INTO THE SOUTHERN U.P....WITH THE DRY
AIRMASS IN PLACE THE MAIN PROBLEM OF SPREADING THE SNOW NORTHWARD.
THE ONLY OTHER ITEM OF CONCERN IS THE LAKE EFFECT SNOW ACROSS THE
KEWEENAW PENINSULA. THE NAM/GFS/LOCAL WRF-ARW DEPICT A DECENT LOW
LEVEL CONVERGENCE ZONE SETTING UP THERE...IN ADDITION TO A WARMER
SOUNDING PROFILE FAVORING MORE DENDRITE PRODUCTION. THUS...SNOW TO
WATER RATIOS SHOULD GO UP. SINCE PLENTY OF WIND STILL REMAINS IN THE
BOUNDARY LAYER...AND FORECAST SNOWFALL AMOUNTS OF 3-5 INCHES...HAVE
DECIDED TO EXTEND THE ADVISORY FOR THE KEWEENAW PENINSULA TO 00Z
TUE. AS MENTIONED EARLIER...WARMER AIR MOVES INTO THE CWA...WHICH
SHOULD BRING TEMPS UP 5 TO 8 DEGREES MORE THAN THOSE TODAY.
STILL...THE VALUES REMAIN 10 TO 15 DEGREES BELOW NORMAL.
MON NIGHT INTO TUE...SHRTWV OVER NW MN IS PROGGED TO MOVE THROUGH
UPPER MI TUE MORNING...MAINTAINING COLD AIR OVER THE CWA. THIS
SHRTWV WILL ALSO HELP KEEP THE SYSTEM OVER KANSAS CITY...WHICH IS
SHOWN TO MOVE UP THROUGH LOWER MICHIGAN DURING THIS PERIOD...FAIRLY
PROGRESSIVE. HAVE KEPT CHANCE POPS GOING FOR MONDAY NIGHT ALONG THE
LAKE MICHIGAN SHORELINE FOR ANY FRONTOGENETICAL PCPN THAT MAKES IT
INTO THE CWA. OTHERWISE...THE MAIN CONCERN IS LAKE EFFECT SNOW.
WINDS REMAIN MOSTLY WESTERLY MON NIGHT...FAVORING MAINLY THE WESTERN
U.P.. HARD TO TELL IF THERE WILL BE ANY MAIN CONVERGENT BAND AT THIS
POINT...BUT IF ANYWHERE WOULD PROBABLY BE SITUATED IN NORTHERN
HOUGHTON COUNTY. FOR TUE...WINDS TURN SLIGHTLY MORE TO THE NW IN THE
WAKE OF THE SYSTEM MOVING THROUGH LOWER MICHIGAN. HOWEVER...IT NEVER
LOOKS LIKE THEY WILL FULLY GO NW AS MODELS SHOW ANOTHER SHRTWV
TROUGH DROPPING SOUTH THROUGH SOUTH CENTRAL CANADA...WHICH WOULD
HELP TO KEEP THE FLOW BACKED MORE. THUS...THE BEST AREA FOR LAKE
EFFECT ON TUE REMAINS FROM ONTONAGON COUNTY THROUGH THE
KEWEENAW...AND HAVE RAISED POPS TO LIKELY. RAISED TEMPS A FEW
DEGREES MONDAY NIGHT WITH CLOUD COVER FROM THE SYSTEM KEEPING TEMPS
UP. TUES TEMPS LOOK FAIRLY SIMILAR TO MON.
TUE NIGHT INTO WED...SHRTWV TROUGH DROPPING SOUTH THROUGH SOUTH
CENTRAL CANADA LOOKS FAIRLY POTENT...AND THE GFS/UKMET/ECMWF REFLECT
THIS IN 850MB TEMP FIELDS...SHOWING ANOTHER BATCH OF -25 TO -28C AIR
DROPPING INTO UPPER MI BY WED MORNING. THE SURFACE COLD FRONT
ASSOCIATED WITH THE TROUGH SHOULD INTENSIFY THE LOW LEVEL
CONVERGENCE OVER THE KEWEENAW PENINSULA TUE NIGHT...WHICH WILL THEN
DROP SOUTH THROUGH THE CWA ON WED. THUS...LIKELY POPS SEEM
REASONABLE AT LEAST FOR THE NW SNOWBELTS. WITH THE COLD AIR MOVING
IN ON WED...COOLED HIGH TEMPS A FEW DEGREES.
BEYOND WED...ECMWF/GFS SHOW STRONG WARM ADVECTION ACROSS THE CWA ON
THU...WHICH SHOULD HELP MODERATE TEMPS. NO CHANGES MADE TO THE
FORECAST AFTER WED.
&&
.AVIATION (FOR THE 06Z TAF ISSUANCE)...
WITH WNW FLOW OF VERY COLD AIR FCST TO PERSIST THRU SUN EVNG...
EXPECT LTL CHG IN PREVAILING CONDITIONS AT BOTH SITES THIS FCST PD.
AT CMX... LES/IFR TO LIFR VSBYS/IFR CIGS OCNL MVFR CIGS WL BE THE
RULE WITH GUSTY WINDS AT TIMES CAUSING CONSIDERABLE BLOWING OF THE
FINE SN FLAKES THAT WL EFFECTIVELY REDUCE VSBY. LOOK FOR CONDITIONS
AT SAW TO BE VFR FOR THE MOST PART WITH LESS LK MODIFICATION THERE.
SOME BKN SC/HI MVFR CIGS MAY FORM SUN AFTN WITHIN H85 THERMAL TROF
AS WAS THE CASE ON SAT AFTN.
&&
.MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)...
NW WINDS WILL REMAIN IN THE 15 TO 30 KNOT RANGE TODAY AND TONIGHT AS
A TIGHT GRADIENT PERSISTS BETWEEN ARCTIC HIGH PRESSURE BUILDING
SOUTHEAST FROM THE PLAINS AND A LINGERING TROUGH INTO THE UPPER
GREAT LAKES. 15 TO 25 KNOT WESTERLY WINDS ARE EXPECTED MONDAY INTO
EARLY TUESDAY AS A WEAK LOW MOVES THROUGH THE CENTRAL GREAT LAKES
AND A LOW PRESSURE TROUGH DEVELOPS OVER NORTHERN ONTARIO. A COLD
FRONT WILL MOVE THROUGH TUESDAY NIGHT WITH WINDS VEERING NORTHERLY
AND INCREASING TO 15 TO 30 KNOTS BY WED. HEAVY FREEZING SPRAY WILL
CONTINUE INTO MONDAY DUE TO THE STRONG WINDS AND VERY COLD ARCTIC
AIR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
MICHIGAN...
  WIND CHILL ADVISORY UNTIL 1 PM EST /NOON CST/ THIS AFTERNOON FOR
    MIZ002-004-005-009>014-084.
  LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING MIZ006-007.
  LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ085.
  LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 PM EST
    MONDAY FOR MIZ001-003.
  LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST MONDAY
    FOR MIZ002.
LAKE SUPERIOR...
  HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST MONDAY LSZ162-263>267.
LAKE MICHIGAN...
  HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST MONDAY FOR LMZ248-250.
&&
$$
SYNOPSIS/DISCUSSION...AJ
AVIATION/MARINE...JLB
</pre> mi
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MARQUETTE MI
830 PM EST SAT JAN 19 2008
.UPDATE...
SINCE WRNGS FOR ALGER/LUCE COUNTIES HAVE NOW VERIFIED...UPDATED TO
EXTEND GOING LES WRNG FOR THOSE ZNS THRU THE DAY ON SUN. OTHER SGNFT
CHG TO FCST WAS TO MODIFY TIMING FOR LES ADVY IN NRN SCHOOLCRAFT
COUNTY. LES BANDS HAVE BEEN N OF THE COUNTY FOR QUITE SOME TIME...SO
COULD NOT RATIONALIZE CONTINUED ADVY THERE. HOWEVER...SHRTWV DIVING
SEWD THRU NW ONTARIO TOWARD NW LK SUP AS SHOWN ON WV IMAGERY IS
BEGINNING TO CAUSE WINDS OVER LK SUP TO VEER MORE NW. SO EXPECT
BANDS/SHARPER LLVL CNVGC NOW IMPACTING ERN ALGER/NRN LUCE COUNTIES
TO SPREAD INLAND OVERNGT INTO AT LEAST INTO AREAS N OF M-28 AS
HINTED AT BY LATEST NAM/GFS/RUC13 MODELS. SO...STARTED LES ADVY AT
06Z AND RAN HEADLINE FOR NRN SCHOOLCRAFT THRU THE DAY ON SUN WITH
LES EXPECTED TO PERSIST IN COLD WNW FLOW OVER ERN ALGER/LUCE/NRN
SCHOOLCRAFT ZNS.
OTRW...OTHER GOING HEADLINES FOR LES/WIND CHILLS SEEM ON TRACK.
&&
.SYNOPSIS/SHORT TERM (TONIGHT AND SUNDAY)...
THE MAIN CONCERN WITH THIS FORECAST UPDATE IS THE POTENTIAL FOR LAKE
EFFECT SNOWS AND WIND CHILLS TONIGHT AND SUNDAY.
WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER EASTERN
U.P. A RIDGE IS OVER THE PACIFIC NORTHWEST...WITH A WEAK RIDGE
EXTENDING FROM WESTERN MONTANA NORTHWARD INTO ALBERTA. A WEAK
SHORTWAVE SLIDING DOWN THE LEE OF THE RIDGE IS OVER THE WESTERN U.P.
SURFACE ANALYSIS DEPICTS A 1032MB HIGH IN THE KANSAS CITY AREA WITH
A RIDGE EXTENDING NORTHWEST INTO NORTHERN SASKATCHEWAN. A WEAK
FRONTAL SYSTEM IS WASHING OUT OVER EASTERN LAKE SUPERIOR. A THERMAL
TROUGH IS PRODUCING LAKE-850MB DELTA-T OVER LAKE SUPERIOR OF 29C.
THE FRONT IS PRODUCING LOW LEVEL CONVERGENCE OVER LAKE SUPERIOR.
TOGETHER WITH THE SHORTWAVE ENERGY ARE GENERATING LAKE EFFECT SNOWS.
THE ANTICYCLONIC AHEAD OF THE RIDGE IS CAUSING STRONG WEST AND
NORTHWEST FLOW ACROSS THE AREA. THUS AREAS DOWNWIND OF LAKE SUPERIOR
CONTINUE TO PRODUCE LAKE EFFECT SNOWS. SIGNIFICANT ACCUMULATION OF
LES WILL CONTINUE THROUGH TONIGHT AS MORE WEAK SHORTWAVE SWEEP
THROUGH THE AREA TONIGHT...AND THE DELTA-T REMAIN MORE THAN 29C. LOW
LEVEL CONVERGENCE IS EXPECTED TO CONTINUE OVER LAKE SUPERIOR. THUS
LITTLE CHANGE IN THE WEATHER CAN BE EXPECTED TONIGHT.
THE LONGWAVE TROUGH WILL REMAIN OVER EASTERN CANADA ON SUNDAY. THE
TROUGH THAT WAS OVER THE U.P. TODAY WILL ROTATE RAPIDLY INTO NEW
ENGLAND AS WEAKER SHORTWAVE SWEEP THROUGH THE AREA. ANOTHER TROUGH
WILL DEVELOP IN THE LEE OF THE PACIFIC RIDGE AND SLIDE INTO SOUTH
CENTRAL CANADA. THE SURFACE HIGH OVER KANSAS CITY WILL MOVE EAST
INTO THE WESTERN KENTUCKY AND THE SOUTHERN OHIO RIVER VALLEY. THE
WEAK COLD FRONT WILL STILL STRETCH ACROSS EASTERN LAKE SUPERIOR.
HEAVY LES CAN BE EXPECTED ALONG THE LAKE SUPERIOR SHORE WHICH IS
WHAT IS IN THERE ALREADY.
&&
.LONG TERM (SUNDAY NIGHT THROUGH NEXT SATURDAY)...
MODELS INDICATE THAT ARCTIC AIRMASS COULD PERSIST INTO AT LEAST
MIDWEEK AS BITTER COLD TEMPS AND WIND CHILLS REMAIN A CONCERN INTO
THE EARLY PART OF NEXT WEEK. HEADLINES FOR WIND CHILLS WILL LIKELY
NEED TO BE EXTENDED SUNDAY NIGHT INTO MON AND MAYBE EVEN INTO TUE AS
VERY COLD PATTERN PERSISTS. AMPLIFIED UPR RIDGE OVER WESTERN CANADA
IS ALLOWING POLAR AIR A CLEAR PATH TO DESCEND INTO THE UPR GREAT
LAKES IN A NRLY FLOW. EXPECT DOUBLE DIGITS BLO ZERO TO REMAIN THE
RULE OVER THE INTERIOR OF WEST AND CENTRAL COUNTIES UNDER GENERALLY
CLEAR SKIES AND WRLY FLOW OVER THE NEXT FEW NIGHT WHILE HIGH TEMPS
STRUGGLE TO REACH NEAR ZERO. WRLY FLOW WILL CONTINUE SOME LES OVER
THE KEWEENAW PENINSULA AND ERN COUNTY SHORELINES SUN NIGHT ALTHOUGH
FLOW BACKING MORE WSW SHOULD PUSH LES BANDS BACK OFF THE ERN COUNTY
SHORELINES BY MON. POOR SNOW GROWTH SHOULD LIMIT ACCUMULATIONS TO 1
TO LOCALLY 4 INCHES SUN NIGHT INTO MON SO DO NOT ANTICIPATE
HEADLINES FOR SNOW OR BLOWING SNOW.
BY TUE...GFS...UKMET AND ECMWF ALL ADVERTISE ANOTHER SHORTWAVE
DESCENDING DOWN ACROSS UPR MI REINFORCING THE ARCTIC AIR OVER THE
REGION WITH 850 MB TEMPS DROPPING TO AROUND -25C OR COLDER BY LATE
TUE INTO WED. TROFFING OVER LAKE SUPERIOR IS ENHANCED BY THIS
SHORTWAVE AND COLDER AIR WHICH WILL IN TURN ENHANCE LOW-LVL
CONVERGENCE OVER THE KEWEENAW PENINSULA AND ERN SHORELINE AREAS.
LOOK FOR LES TO PICK UP OVER THESE AREAS FOR LATE TUE INTO
WED.
MODELS THEN POINT TO A TRANSITION IN THE PATTERN FOR LATE NEXT WEEK.
OPERATIONAL 00Z ECMWF RUN WAS GENERALLY FAVORED BY NCEP AND FOLLOWED
IT FOR DETAILS. TROF BEGINS TO TAKE SHAPE OVER THE WRN CONUS BY THE
END OF THE WEEK AS RIDGING BEGINS TO MOVE INTO THE NRN PLAINS.
MODERATING TEMPS OVER THE NRN PLAINS WILL GRADUALLY WORK INTO THE
UPR GREAT LAKES BY THE END OF THE WEEK AS 850 MB TEMPS REBOUNDING TO
AROUND -12C OR SO SHOULD HELP SHAKE BITTER COLD TEMPS FROM THE
REGION. ARRIVAL OF SHORTWAVE AND ASSOC SFC LOW PRES SYSTEM FOR FRI
INTO SAT WILL WARRANT LOW CHC POPS ACROSS THE AREA.
&&
.AVIATION (FOR THE 00Z TAF ISSUANCE)...
WITH WNW FLOW OF VERY COLD AIR FCST TO PERSIST THRU SUN...EXPECT LTL
CHG IN PREVAILING CONDITIONS AT BOTH SITES THIS FCST PD. AT CMX...
LES/IFR TO LIFR VSBYS/IFR CIGS OCNL MVFR CIGS WL BE THE RULE WITH
GUSTY WINDS AT TIMES CAUSING CONSIDERABLE BLOWING OF THE FINE SN
FLAKES THAT WL EFFECTIVELY REDUCE VSBY. LOOK FOR CONDITIONS AT SAW
TO BE VFR FOR THE MOST PART WITH LESS LK MODIFICATION THERE. SOME
BKN SC/HI MVFR CIGS MAY FORM SUN AFTN WITHIN H85 THERMAL TROF AS WAS
THE CASE ON SAT AFTN.
&&
.MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)...THE
FRONT OVER EASTERN LAKE SUPERIOR WILL REMAIN STATIONARY THROUGH
MONDAY WHILE WEAKENING. W-NW FLOW WILL REMAIN IN THE 15 TO 30 KT
RANGE DURING THIS PERIOD...WITH THE STRONGEST WINDS OCCURRING
TONIGHT. A RIDGE OF HIGH PRESSURE WILL CROSS LAKE SUPERIOR MONDAY
NIGHT INTO TUESDAY...CAUSING WINDS TO BACK MORE TOWARDS THE
WEST...THOUGH SPEEDS REMAIN BETWEEN 15 AND 25 KT. A COLD FRONT
PASSAGE IS EXPECTED TUE NIGHT. BEHIND THIS FRONT...LOOK FOR WINDS TO
FALL BELOW 20 KT. HEAVY FREEZING SPRAY WILL CONTINUE THROUGH SUNDAY
NIGHT DUE TO THE STRONG WINDS AND PERSISTENT ARCTIC AIRMASS. ANOTHER
LOW WILL LIFT OUT OF THE MIDDLE MISSISSIPPI RIVER VALLY THROUGH
NORTHERN LOWER MICHIGAN LATE ON MONDAY AND TO SOUTHERN QUEBEC ON
TUESDAY. ANOTHER HIGH PRESSURE SYSTEM DEVELOP OVER THE CENTRAL
PLAINS ON TUESDAY WILL MOVE INTO THE OHIO RIVER VALLEY AS A LOW
DEVELOPS OVER THE LAKE SUPERIOR. COLD TEMPERATURES AND STRONG WINDS
WILL PRODUCE CONSIDERABLE HEAVY FREEZING SPRAY THROUGH MONDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
MICHIGAN...WIND CHILL ADVISORY UNTIL 1 PM EST /12 PM CST/ SUNDAY FOR MIZ002-
     004-005-009>014-084.
     LAKE EFFECT SNOW ADVISORY FROM 1 AM TO 7 PM EST SUNDAY FOR
     MIZ085.
     LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST SUNDAY
     FOR MIZ001>003.
     LAKE EFFECT SNOW WARNING UNTIL 7 PM EST SUNDAY FOR MIZ006-007.
LAKE SUPERIOR...HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST MONDAY FOR
     LSZ263>267.
LAKE MICHIGAN...HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST MONDAY
     FOR LMZ221-248-250.
&&
$$
UPDATE...KC
SHORT TERM...DLG
LONG TERM...VOSS
AVIATION...KC
MARINE...DLG
</pre> mi
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MARQUETTE MI
630 PM EST SAT JAN 19 2008
UPDATED FOR 00Z TAFS
.SYNOPSIS/SHORT TERM (TONIGHT AND SUNDAY)...
THE MAIN CONCERN WITH THIS FORECAST UPDATE IS THE POTENTIAL FOR LAKE
EFFECT SNOWS AND WIND CHILLS TONIGHT AND SUNDAY.
WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER EASTERN
U.P. A RIDGE IS OVER THE PACIFIC NORTHWEST...WITH A WEAK RIDGE
EXTENDING FROM WESTERN MONTANA NORTHWARD INTO ALBERTA. A WEAK
SHORTWAVE SLIDING DOWN THE LEE OF THE RIDGE IS OVER THE WESTERN U.P.
SURFACE ANALYSIS DEPICTS A 1032MB HIGH IN THE KANSAS CITY AREA WITH
A RIDGE EXTENDING NORTHWEST INTO NORTHERN SASKATCHEWAN. A WEAK
FRONTAL SYSTEM IS WASHING OUT OVER EASTERN LAKE SUPERIOR. A THERMAL
TROUGH IS PRODUCING LAKE-850MB DELTA-T OVER LAKE SUPERIOR OF 29C.
THE FRONT IS PRODUCING LOW LEVEL CONVERGENCE OVER LAKE SUPERIOR.
TOGETHER WITH THE SHORTWAVE ENERGY ARE GENERATING LAKE EFFECT SNOWS.
THE ANTICYCLONIC AHEAD OF THE RIDGE IS CAUSING STRONG WEST AND
NORTHWEST FLOW ACROSS THE AREA. THUS AREAS DOWNWIND OF LAKE SUPERIOR
CONTINUE TO PRODUCE LAKE EFFECT SNOWS. SIGNIFICANT ACCUMULATION OF
LES WILL CONTINUE THROUGH TONIGHT AS MORE WEAK SHORTWAVE SWEEP
THROUGH THE AREA TONIGHT...AND THE DELTA-T REMAIN MORE THAN 29C. LOW
LEVEL CONVERGENCE IS EXPECTED TO CONTINUE OVER LAKE SUPERIOR. THUS
LITTLE CHANGE IN THE WEATHER CAN BE EXPECTED TONIGHT.
THE LONGWAVE TROUGH WILL REMAIN OVER EASTERN CANADA ON SUNDAY. THE
TROUGH THAT WAS OVER THE U.P. TODAY WILL ROTATE RAPIDLY INTO NEW
ENGLAND AS WEAKER SHORTWAVE SWEEP THROUGH THE AREA. ANOTHER TROUGH
WILL DEVELOP IN THE LEE OF THE PACIFIC RIDGE AND SLIDE INTO SOUTH
CENTRAL CANADA. THE SURFACE HIGH OVER KANSAS CITY WILL MOVE EAST
INTO THE WESTERN KENTUCKY AND THE SOUTHERN OHIO RIVER VALLEY. THE
WEAK COLD FRONT WILL STILL STRETCH ACROSS EASTERN LAKE SUPERIOR.
HEAVY LES CAN BE EXPECTED ALONG THE LAKE SUPERIOR SHORE WHICH IS
WHAT IS IN THERE ALREADY.
&&
.LONG TERM (SUNDAY NIGHT THROUGH NEXT SATURDAY)...
MODELS INDICATE THAT ARCTIC AIRMASS COULD PERSIST INTO AT LEAST
MIDWEEK AS BITTER COLD TEMPS AND WIND CHILLS REMAIN A CONCERN INTO
THE EARLY PART OF NEXT WEEK. HEADLINES FOR WIND CHILLS WILL LIKELY
NEED TO BE EXTENDED SUNDAY NIGHT INTO MON AND MAYBE EVEN INTO TUE AS
VERY COLD PATTERN PERSISTS. AMPLIFIED UPR RIDGE OVER WESTERN CANADA
IS ALLOWING POLAR AIR A CLEAR PATH TO DESCEND INTO THE UPR GREAT
LAKES IN A NRLY FLOW. EXPECT DOUBLE DIGITS BLO ZERO TO REMAIN THE
RULE OVER THE INTERIOR OF WEST AND CENTRAL COUNTIES UNDER GENERALLY
CLEAR SKIES AND WRLY FLOW OVER THE NEXT FEW NIGHT WHILE HIGH TEMPS
STRUGGLE TO REACH NEAR ZERO. WRLY FLOW WILL CONTINUE SOME LES OVER
THE KEWEENAW PENINSULA AND ERN COUNTY SHORELINES SUN NIGHT ALTHOUGH
FLOW BACKING MORE WSW SHOULD PUSH LES BANDS BACK OFF THE ERN COUNTY
SHORELINES BY MON. POOR SNOW GROWTH SHOULD LIMIT ACCUMULATIONS TO 1
TO LOCALLY 4 INCHES SUN NIGHT INTO MON SO DO NOT ANTICIPATE
HEADLINES FOR SNOW OR BLOWING SNOW.
BY TUE...GFS...UKMET AND ECMWF ALL ADVERTISE ANOTHER SHORTWAVE
DESCENDING DOWN ACROSS UPR MI REINFORCING THE ARCTIC AIR OVER THE
REGION WITH 850 MB TEMPS DROPPING TO AROUND -25C OR COLDER BY LATE
TUE INTO WED. TROFFING OVER LAKE SUPERIOR IS ENHANCED BY THIS
SHORTWAVE AND COLDER AIR WHICH WILL IN TURN ENHANCE LOW-LVL
CONVERGENCE OVER THE KEWEENAW PENINSULA AND ERN SHORELINE AREAS.
LOOK FOR LES TO PICK UP OVER THESE AREAS FOR LATE TUE INTO
WED.
MODELS THEN POINT TO A TRANSITION IN THE PATTERN FOR LATE NEXT WEEK.
OPERATIONAL 00Z ECMWF RUN WAS GENERALLY FAVORED BY NCEP AND FOLLOWED
IT FOR DETAILS. TROF BEGINS TO TAKE SHAPE OVER THE WRN CONUS BY THE
END OF THE WEEK AS RIDGING BEGINS TO MOVE INTO THE NRN PLAINS.
MODERATING TEMPS OVER THE NRN PLAINS WILL GRADUALLY WORK INTO THE
UPR GREAT LAKES BY THE END OF THE WEEK AS 850 MB TEMPS REBOUNDING TO
AROUND -12C OR SO SHOULD HELP SHAKE BITTER COLD TEMPS FROM THE
REGION. ARRIVAL OF SHORTWAVE AND ASSOC SFC LOW PRES SYSTEM FOR FRI
INTO SAT WILL WARRANT LOW CHC POPS ACROSS THE AREA.
&&
.AVIATION (FOR THE 00Z TAF ISSUANCE)...
WITH WNW FLOW OF VERY COLD AIR FCST TO PERSIST THRU SUN...EXPECT LTL
CHG IN PREVAILING CONDITIONS AT BOTH SITES THIS FCST PD. AT CMX...
LES/IFR TO LIFR VSBYS/IFR CIGS OCNL MVFR CIGS WL BE THE RULE WITH
GUSTY WINDS AT TIMES CAUSING CONSIDERABLE BLOWING OF THE FINE SN
FLAKES THAT WL EFFECTIVELY REDUCE VSBY. LOOK FOR CONDITIONS AT SAW
TO BE VFR FOR THE MOST PART WITH LESS LK MODIFICATION THERE. SOME
BKN SC/HI MVFR CIGS MAY FORM SUN AFTN WITHIN H85 THERMAL TROF AS WAS
THE CASE ON SAT AFTN.
&&
.MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)...THE
FRONT OVER EASTERN LAKE SUPERIOR WILL REMAIN STATIONARY THROUGH
MONDAY WHILE WEAKENING. W-NW FLOW WILL REMAIN IN THE 15 TO 30 KT
RANGE DURING THIS PERIOD...WITH THE STRONGEST WINDS OCCURRING
TONIGHT. A RIDGE OF HIGH PRESSURE WILL CROSS LAKE SUPERIOR MONDAY
NIGHT INTO TUESDAY...CAUSING WINDS TO BACK MORE TOWARDS THE
WEST...THOUGH SPEEDS REMAIN BETWEEN 15 AND 25 KT. A COLD FRONT
PASSAGE IS EXPECTED TUE NIGHT. BEHIND THIS FRONT...LOOK FOR WINDS TO
FALL BELOW 20 KT. HEAVY FREEZING SPRAY WILL CONTINUE THROUGH SUNDAY
NIGHT DUE TO THE STRONG WINDS AND PERSISTENT ARCTIC AIRMASS. ANOTHER
LOW WILL LIFT OUT OF THE MIDDLE MISSISSIPPI RIVER VALLY THROUGH
NORTHERN LOWER MICHIGAN LATE ON MONDAY AND TO SOUTHERN QUEBEC ON
TUESDAY. ANOTHER HIGH PRESSURE SYSTEM DEVELOP OVER THE CENTRAL
PLAINS ON TUESDAY WILL MOVE INTO THE OHIO RIVER VALLEY AS A LOW
DEVELOPS OVER THE LAKE SUPERIOR. COLD TEMPERATURES AND STRONG WINDS
WILL PRODUCE CONSIDERABLE HEAVY FREEZING SPRAY THROUGH MONDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
MICHIGAN...
  LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST SUNDAY
     FOR MIZ001>003.
  LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ085.
  LAKE EFFECT SNOW WARNING UNTIL 7 AM EST SUNDAY FOR MIZ006-007.
  WIND CHILL ADVISORY UNTIL 1 PM EST /12 PM CST/ SUNDAY FOR
     MIZ002-004-005-009>014-084.
LAKE SUPERIOR...
  HEAVY FREEZING SPRAY WARNING UNTIL 4 AM EST MONDAY LSZ162-263>267.
LAKE MICHIGAN...
  HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST SUNDAY
    LMZ221-248-250.
&&
$$
SHORT TERM...DLG
LONG TERM...VOSS
AVIATION...KC
MARINE...DLG
</pre> mi
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
500 PM EST SAT JAN 19 2008
.SYNOPSIS/SHORT TERM (TONIGHT AND SUNDAY)...
THE MAIN CONCERN WITH THIS FORECAST UPDATE IS THE POTENTIAL FOR LAKE
EFFECT SNOWS AND WIND CHILLS TONIGHT AND SUNDAY.
WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER EASTERN
U.P. A RIDGE IS OVER THE PACIFIC NORTHWEST...WITH A WEAK RIDGE
EXTENDING FROM WESTERN MONTANA NORTHWARD INTO ALBERTA. A WEAK
SHORTWAVE SLIDING DOWN THE LEE OF THE RIDGE IS OVER THE WESTERN U.P.
SURFACE ANALYSIS DEPICTS A 1032MB HIGH IN THE KANSAS CITY AREA WITH
A RIDGE EXTENDING NORTHWEST INTO NORTHERN SASKATCHEWAN. A WEAK
FRONTAL SYSTEM IS WASHING OUT OVER EASTERN LAKE SUPERIOR. A THERMAL
TROUGH IS PRODUCING LAKE-850MB DELTA-T OVER LAKE SUPERIOR OF 29C.
THE FRONT IS PRODUCING LOW LEVEL CONVERGENCE OVER LAKE SUPERIOR.
TOGETHER WITH THE SHORTWAVE ENERGY ARE GENERATING LAKE EFFECT SNOWS.
THE ANTICYCLONIC AHEAD OF THE RIDGE IS CAUSING STRONG WEST AND
NORTHWEST FLOW ACROSS THE AREA. THUS AREAS DOWNWIND OF LAKE SUPERIOR
CONTINUE TO PRODUCE LAKE EFFECT SNOWS. SIGNIFICANT ACCUMULATION OF
LES WILL CONTINUE THROUGH TONIGHT AS MORE WEAK SHORTWAVE SWEEP
THROUGH THE AREA TONIGHT...AND THE DELTA-T REMAIN MORE THAN 29C. LOW
LEVEL CONVERGENCE IS EXPECTED TO CONTINUE OVER LAKE SUPERIOR. THUS
LITTLE CHANGE IN THE WEATHER CAN BE EXPECTED TONIGHT.
THE LONGWAVE TROUGH WILL REMAIN OVER EASTERN CANADA ON SUNDAY. THE
TROUGH THAT WAS OVER THE U.P. TODAY WILL ROTATE RAPIDLY INTO NEW
ENGLAND AS WEAKER SHORTWAVE SWEEP THROUGH THE AREA. ANOTHER TROUGH
WILL DEVELOP IN THE LEE OF THE PACIFIC RIDGE AND SLIDE INTO SOUTH
CENTRAL CANADA. THE SURFACE HIGH OVER KANSAS CITY WILL MOVE EAST
INTO THE WESTERN KENTUCKY AND THE SOUTHERN OHIO RIVER VALLEY. THE
WEAK COLD FRONT WILL STILL STRETCH ACROSS EASTERN LAKE SUPERIOR.
HEAVY LES CAN BE EXPECTED ALONG THE LAKE SUPERIOR SHORE WHICH IS
WHAT IS IN THERE ALREADY.
&&
.LONG TERM (SUNDAY NIGHT THROUGH NEXT SATURDAY)...
MODELS INDICATE THAT ARCTIC AIRMASS COULD PERSIST INTO AT LEAST
MIDWEEK AS BITTER COLD TEMPS AND WIND CHILLS REMAIN A CONCERN INTO
THE EARLY PART OF NEXT WEEK. HEADLINES FOR WIND CHILLS WILL LIKELY
NEED TO BE EXTENDED SUNDAY NIGHT INTO MON AND MAYBE EVEN INTO TUE AS
VERY COLD PATTERN PERSISTS. AMPLIFIED UPR RIDGE OVER WESTERN CANADA
IS ALLOWING POLAR AIR A CLEAR PATH TO DESCEND INTO THE UPR GREAT
LAKES IN A NRLY FLOW. EXPECT DOUBLE DIGITS BLO ZERO TO REMAIN THE
RULE OVER THE INTERIOR OF WEST AND CENTRAL COUNTIES UNDER GENERALLY
CLEAR SKIES AND WRLY FLOW OVER THE NEXT FEW NIGHT WHILE HIGH TEMPS
STRUGGLE TO REACH NEAR ZERO. WRLY FLOW WILL CONTINUE SOME LES OVER
THE KEWEENAW PENINSULA AND ERN COUNTY SHORELINES SUN NIGHT ALTHOUGH
FLOW BACKING MORE WSW SHOULD PUSH LES BANDS BACK OFF THE ERN COUNTY
SHORELINES BY MON. POOR SNOW GROWTH SHOULD LIMIT ACCUMULATIONS TO 1
TO LOCALLY 4 INCHES SUN NIGHT INTO MON SO DO NOT ANTICIPATE
HEADLINES FOR SNOW OR BLOWING SNOW.
BY TUE...GFS...UKMET AND ECMWF ALL ADVERTISE ANOTHER SHORTWAVE
DESCENDING DOWN ACROSS UPR MI REINFORCING THE ARCTIC AIR OVER THE
REGION WITH 850 MB TEMPS DROPPING TO AROUND -25C OR COLDER BY LATE
TUE INTO WED. TROFFING OVER LAKE SUPERIOR IS ENHANCED BY THIS
SHORTWAVE AND COLDER AIR WHICH WILL IN TURN ENHANCE LOW-LVL
CONVERGENCE OVER THE KEWEENAW PENINSULA AND ERN SHORELINE AREAS.
LOOK FOR LES TO PICK UP OVER THESE AREAS FOR LATE TUE INTO
WED.
MODELS THEN POINT TO A TRANSITION IN THE PATTERN FOR LATE NEXT WEEK.
OPERATIONAL 00Z ECMWF RUN WAS GENERALLY FAVORED BY NCEP AND FOLLOWED
IT FOR DETAILS. TROF BEGINS TO TAKE SHAPE OVER THE WRN CONUS BY THE
END OF THE WEEK AS RIDGING BEGINS TO MOVE INTO THE NRN PLAINS.
MODERATING TEMPS OVER THE NRN PLAINS WILL GRADUALLY WORK INTO THE
UPR GREAT LAKES BY THE END OF THE WEEK AS 850 MB TEMPS REBOUNDING TO
AROUND -12C OR SO SHOULD HELP SHAKE BITTER COLD TEMPS FROM THE
REGION. ARRIVAL OF SHORTWAVE AND ASSOC SFC LOW PRES SYSTEM FOR FRI
INTO SAT WILL WARRANT LOW CHC POPS ACROSS THE AREA.
&&
.AVIATION (FOR THE 18Z TAF ISSUANCE)...
PERSISTENCE IS THE WAY TO GO WITH THE TAF FORECAST THROUGH THE NEXT
24 HOURS AS GUIDANCE SHOWING THE PATTERN WILL CHANGE LITTLE.
BASICALLY...NORTHWEST WINDS CONTINUE TO DRIVE ARCTIC AIR ACROSS LAKE
SUPERIOR INTO UPPER MICHIGAN...WHICH WILL HELP MAINTAIN LAKE EFFECT
SNOW SHOWERS WITH FINE SNOWFLAKES. THESE FINER SNOWFLAKES COMBINED
WITH THE WIND HAVE KEPT CMX BOUNCING BETWEEN LIFR AND IFR FOR
VSBY...AND IFR TO MVFR FOR CEILING FOR THE PAST 12 HOURS...AND THIS
SHOULD CONTINUE THROUGH TONIGHT. AT SAW...LAKE EFFECT BANDS OFF
WESTERN LAKE SUPERIOR CANNOT PENETRATE THAT FAR INLAND...THUS VFR
CONDITIONS ARE FORECAST.
&&
.MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)...THE
FRONT OVER EASTERN LAKE SUPERIOR WILL REMAIN STATIONARY THROUGH
MONDAY WHILE WEAKENING. W-NW FLOW WILL REMAIN IN THE 15 TO 30 KT
RANGE DURING THIS PERIOD...WITH THE STRONGEST WINDS OCCURRING
TONIGHT. A RIDGE OF HIGH PRESSURE WILL CROSS LAKE SUPERIOR MONDAY
NIGHT INTO TUESDAY...CAUSING WINDS TO BACK MORE TOWARDS THE
WEST...THOUGH SPEEDS REMAIN BETWEEN 15 AND 25 KT. A COLD FRONT
PASSAGE IS EXPECTED TUE NIGHT. BEHIND THIS FRONT...LOOK FOR WINDS TO
FALL BELOW 20 KT. HEAVY FREEZING SPRAY WILL CONTINUE THROUGH SUNDAY
NIGHT DUE TO THE STRONG WINDS AND PERSISTENT ARCTIC AIRMASS. ANOTHER
LOW WILL LIFT OUT OF THE MIDDLE MISSISSIPPI RIVER VALLY THROUGH
NORTHERN LOWER MICHIGAN LATE ON MONDAY AND TO SOUTHERN QUEBEC ON
TUESDAY. ANOTHER HIGH PRESSURE SYSTEM DEVELOP OVER THE CENTRAL
PLAINS ON TUESDAY WILL MOVE INTO THE OHIO RIVER VALLEY AS A LOW
DEVELOPS OVER THE LAKE SUPERIOR. COLD TEMPERATURES AND STRONG WINDS
WILL PRODUCE CONSIDERABLE HEAVY FREEZING SPRAY THROUGH MONDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
MICHIGAN...
  LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST SUNDAY
     FOR MIZ001>003.
  LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ085.
  LAKE EFFECT SNOW WARNING UNTIL 7 AM EST SUNDAY FOR MIZ006-007.
  WIND CHILL ADVISORY UNTIL 1 PM EST /12 PM CST/ SUNDAY FOR
     MIZ002-004-005-009>014-084.
LAKE SUPERIOR...
  HEAVY FREEZING SPRAY WARNING UNTIL 4 AM EST MONDAY LSZ162-263>267.
LAKE MICHIGAN...
  HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST SUNDAY
    LMZ221-248-250.
&&
$$
SHORT TERM...DLG
LONG TERM...VOSS
AVIATION/MARINE...DLG
</pre> mi
AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE MARQUETTE MI
1223 PM EST SAT JAN 19 2008
.DISCUSSION...
MAIN FORECAST CONCERNS ARE LES TRENDS ALONG WITH TEMPS/WIND CHILLS.
WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER EASTERN
CANADA DRAPED SOUTHWEST THROUGH THE UPPER GREAT LAKES...THEN INTO
SOUTH CENTRAL PLAINS...AND A RIDGE ALONG THE PACIFIC COAST. WEAK
SHORTWAVES ARE SLIDING DOWN THE LEE OF THE RIDGE AND TRACKING
THROUGH THE AREA. SURFACE ANALYSIS DEPICTS A POWERFUL RIDGE
EXTENDING FROM TEXAS NORTH THROUGH THE NORTHERN PLAINS INTO CENTRAL
CANADA. THIS CONTINUES TO DRAW VERY COLD AIR FROM CENTRAL CANADA
INTO THE UPPER GREAT LAKES. A WEAK STATIONARY FRONT EXTENDS FROM
THE LOWER GREAT LAKES INTO EASTERN LAKE SUPERIOR. THE COLD AIR AND
WEAK FRONTAL SYSTEM CONTINUES TO PRODUCE LAKE EFFECTS SNOWS OVER
EASTERN PART OF THE CWA AND ALONG WEST COAST OF THE CWA FROM
ONTONAGON NORTHEAST THROUGH THE KEWEENAW PENINSULA.
THIS AFTERNOON...THE LONGWAVE TROUGH WILL REMAIN NEARLY STATIONARY
OVER THE FORECAST AREA AS WEAK SHORTWAVE SWEEP THROUGH THE BASE OF
THE TROUGH. ONE OF THE SHORTWAVE WILL MOVE INTO THE WEST END OF THE
U.P. BY LATE AFTERNOON. THE SURFACE RIDGE WILL SHIFT ONLY A LITTLE
TOWARDS THE MIDDLE MISSISSIPPI RIVER VALLEY WHILE THE FRONTAL SYSTEM
REMAINS OVER LAKE SUPERIOR. THE WATER-850MB DELTA-T WILL BE AROUND
28C OR GREAT THROUGH THE AFTERNOON. THIS INDICATES LOW LEVEL
INSTABILITY WILL REMAIN STRONG ENOUGH TO KEEP LAKE EFFECT SNOWS
GOING ACROSS THE AREA. THE FRONTAL SYSTEM WILL KEEP STRONG LOW LEVEL
CONVERGENCE OVER LAKE SUPERIOR. REPORTS FROM SPOTTERS INDICATE
AROUND 5+ INCHES SO FAR OVER ALGER AND NORTHERN LUCE COUNTIES. THUS
PLAN TO KEEP THE WARNING GOING FOR NOW AND ADVISORY ELSEWHERE.
TEMPERATURES ARE WARMING A BIT...HOWEVER...THE WINDS ARE INCREASING
WITH THE APPROACH OF THE SHORTWAVE WHICH WILL KEEP THE LOW WIND
CHILLS GOING THIS AFTERNOON. DO NOT PLAN TO UPDATE.
TONIGHT...LOW LEVEL WINDS ARE EXPECTED TO VEER AGAIN THIS EVENING
IN THE WAKE OF THE MANITOBA SHORTWAVE. HOWEVER...THE COMBINATION OF
STRENGTHENING LAND BREEZES/LAKE INDUCED TROFFING AND THE APPROACH OF
ANOTHER SHRTWV WILL KEEP WINDS MAINLY FROM THE WNW. THE STRONGER LOW
LEVEL CONV WILL FOCUS MAINLY EAST OF MUNISING AND NEAR M-38.
ADDITIONAL AMOUNTS OF 2 TO 6 INCHES EAST AND 1 TO 3 INCHES WEST ARE
EXPECTED. AIDED BY LAKE TROFFING...THE GRADIENT WILL REMAIN STRONG
ENOUGH TONIGHT TO KEEP WINDS NEAR 10 MPH. COMBINED WITH TEMPS
FALLING INTO THE -5 TO -17 RANGE...WIND CHILL VALUES WILL AGAIN FALL
TO TH -25 TO -35 RANGE. SOME VALUES INTO THE WARNING RANGE ARE
POSSIBLE BUT MAY BE MARGINAL GIVEN BALANCE BETWEEN RADIATIONAL
COOLING/MIXING OVER INLAND LOCATIONS. HOWEVER...UPGRADE TO WARNING
MAY BE NEEDED.
SUN AND INTO MON...PERSISTENT WNW FLOW AND LAKE INDUCED WILL KEEP
LES GOING FOR THE WEST(NORTH OF M-28)AND EAST (EAST OF MUNISING)
WITH GRADUAL BACKING TREND ALLOWING LES BANDS TO LIFT OFFSHORE IN
THE EAST AND FOCUS INTO THE KEWEENAW. LIMITING FACTORS WITH
SNOWFLAKE GROWTH REMAIN. SO...OVERALL ACCUMULATIONS WILL MAINLY BE
IN THE 2-5 INCH PER 12 HOURS EAST AND 1-3 INCHES WEST. TEMPERATURES
ARE EXPECTED TO AGAIN FALL TO -10 TO -20 INLAND. LIGHTER WINDS BLO
10 MPH WILL KEEP WIND CHILL VALUES FROM BEING QUITE AS SEVERE.
&&
.AVIATION (FOR THE 18Z TAF ISSUANCE)...
PERSISTENCE IS THE WAY TO GO WITH THE TAF FORECAST THROUGH THE NEXT
24 HOURS AS GUIDANCE SHOWING THE PATTERN WILL CHANGE LITTLE.
BASICALLY...NORTHWEST WINDS CONTINUE TO DRIVE ARCTIC AIR ACROSS LAKE
SUPERIOR INTO UPPER MICHIGAN...WHICH WILL HELP MAINTAIN LAKE EFFECT
SNOW SHOWERS WITH FINE SNOWFLAKES. THESE FINER SNOWFLAKES COMBINED
WITH THE WIND HAVE KEPT CMX BOUNCING BETWEEN LIFR AND IFR FOR
VSBY...AND IFR TO MVFR FOR CEILING FOR THE PAST 12 HOURS...AND THIS
SHOULD CONTINUE THROUGH TONIGHT. AT SAW...LAKE EFFECT BANDS OFF
WESTERN LAKE SUPERIOR CANNOT PENETRATE THAT FAR INLAND...THUS VFR
CONDITIONS ARE FORECAST.
&&
.MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)...
A LOW PRESSURE TROUGH OVER EASTERN LAKE SUPERIOR WILL KEEP REMAIN
STATIONARY THROUGH MONDAY. W-NW FLOW WILL REMAIN IN THE 15 TO 30 KT
RANGE DURING THIS PERIOD...WITH THE STRONGEST WINDS OCCURRING TODAY
AND TONIGHT. A RIDGE OF HIGH PRESSURE WILL CROSS LAKE SUPERIOR
MONDAY NIGHT INTO TUESDAY...CAUSING WINDS TO BACK MORE TOWARDS THE
WEST...THOUGH SPEEDS REMAIN BETWEEN 15 AND 25 KT. A COLD FRONT
PASSAGE IS EXPECTED TUE NIGHT. BEHIND THIS FRONT...LOOK FOR WINDS TO
FALL BELOW 20 KT. HEAVY FREEZING SPRAY WILL CONTINUE THROUGH SUNDAY
NIGHT DUE TO THE STRONG WINDS AND PERSISTENT ARCTIC AIRMASS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
MICHIGAN...
  LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST SUNDAY
     FOR MIZ001>003.
  LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ085.
  LAKE EFFECT SNOW WARNING UNTIL 7 AM EST SUNDAY FOR MIZ006-007.
  WIND CHILL ADVISORY UNTIL 1 PM EST /12 PM CST/ SUNDAY FOR
     MIZ002-004-005-009>011-084.
LAKE SUPERIOR...
  HEAVY FREEZING SPRAY WARNING UNTIL 4 AM EST MONDAY LSZ162-263>267.
LAKE MICHIGAN...
  HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST SUNDAY
    LMZ221-248-250.
&&
$$
SYNOPSIS AND THIS AFTERNOON...DLG
REST OF DISCUSSION...JLB
AVIATION/MARINE...AJ
</pre> mi
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MARQUETTE MI
650 AM EST SAT JAN 19 2008
UPDATED AVIATION SECTION FOR 12Z TAF ISSUANCE.
.DISCUSSION...
MAIN FCST CONCERNS ARE LES TRENDS ALONG WITH TEMPS/WIND CHILLS.
WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH
DOMINATING CNTRL AND ERN NOAM. ONE SHORTWAVE TROUGH EMBEDDED IN THE
CYCLONIC FLOW WAS MOVING THROUGH CNTRL UPPER MI. ANOTHER UPSTREAM
SHRTWV WAS LOCATED NE OF LAKE WINNIPEG. AT THE SFC...LAKE NW FLOW
PREVAILED BTWN ARCTIC HIGH PRES INTO THE PLAINS AND WEAK TROFFING
FROM QUEBEC INTO THE GREAT LAKES. LAKE INDUCED TROFFING WAS EVIDENT
ACROSS SRN LAKE SUPERIOR SUPPORTED BY VERY LARGE LAND/LAKE TEMP
DIFFERENCE. RADAR INDICATED THAT THE DOMINANT BAND INTO THE NE CWA
LAKE SUPERIOR SHORELINE HAD TRANSITIONED TO WEAKER MULTIPLE WIND
PARALLEL BANDS AS WINDS VEERED TO 320 CBL FLOW. OTHERWISE...VERY
COLD AIR HAS MOVED INTO THE REGION WITH TEMPS OVER NRN MN AND WRN
ONTARIO WITH 850 MB TEMPS AOB -30C. SFC TEMPS WERE INTO THE -20 TO
-25 RANGE AND READINGS FROM AROUND ZERO NEAR LAKE SUPERIOR TO -15
BELOW OVER INLAND PORTIONS OF WEST UPPER MI. THE COLD AIR ALONG WITH
WINDS OF 5 TO 15 MPH HAVE DROPPED WIND CHILL VALUES INTO THE
ADVISORY RANGE FROM -20 TO -35.
TODAY...EXPECT WINDS TO GRADUALLY BACK WITH THE APPROACH OF THE
MANITOBA SHORTWAVE. THE NAM AND LCL HIGH RES WRF/ARW THAT HAVE
HANDLED EFFECTS OF LAKE TROFFING REASONABLY WELL SUGGEST THAT
HEAVIER LES BANDS WILL AGAIN SHIFT CLOSER TO THE SHORELINE EAST OF
MUNISING IN THE ERN CWA. TEMP PROFILE...WITH ONLY A SHALLOW OR NO
LAYER ABOVE -17C WERE NOT FAVORABLE FOR DENDRITIC SNOWFLAKE GROWTH
AND SHOULD LIMIT ACCUMULATIONS...DESPITE VERY LARGE INSTABILITY (850
MB TEMPS TO AROUND -26C). HOWEVER...ACCUMULATIONS IN THE 3 TO 7 INCH
RANGE ARE STILL POSSIBLE. OVER THE WEST...THE SHORTER FETCH AND EVEN
COLDER/DRIER AIR WILL KEEP ACCUMULATIONS MAINLY IN THE 1 TO 4 INCH
RANGE. MDLS SHOW THE MOST FAVORABLE LOW LEVEL CONV BTWN
ONTONAGON...M-38 AND HOUGHTON. THE WINDS NEAR THE LAKE INTO THE 15
TO 25 MPH RANGE ALONG WITH THE FINE SNOWFLAKES WILL LIMIT VSBYS AT
TIMES TO AROUND 1/4SM. WIND CHILL VALUES WILL MODERATE WITH DIURNAL
WARMING BUT WILL STILL REMAIN CLOSE TO ADVISORY RANGE DURING THE
AFTERNOON FROM -15 TO -25.
TONIGHT...LOW LEVEL WINDS ARE EXPECTED TO VEER AGAIN THIS EVENING
IN THE WAKE OF THE MANITOBA SHORTWAVE. HOWEVER...THE COMBINATION OF
STRENGTHENING LAND BREEZES/LAKE INDUCED TROFFING AND THE APPROACH OF
ANOTHER SHRTWV WILL KEEP WINDS MAINLY FROM THE WNW. THE STRONGER LOW
LEVEL CONV WILL FOCUS MAINLY EAST OF MUNISING AND NEAR M-38.
ADDITIONAL AMOUNTS OF 2 TO 6 INCHES EAST AND 1 TO 3 INCHES WEST ARE
EXPECTED. AIDED BY LAKE TROFFING...THE GRADIENT WILL REMAIN STRONG
ENOUGH TONIGHT TO KEEP WINDS NEAR 10 MPH. COMBINED WITH TEMPS
FALLING INTO THE -5 TO -17 RANGE...WIND CHILL VALUES WILL AGAIN FALL
TO TH -25 TO -35 RANGE. SOME VALUES INTO THE WARNING RANGE ARE
POSSIBLE BUT MAY BE MARGINAL GIVEN BALANCE BETWEEN RADIATIONAL
COOLING/MIXING OVER INLAND LOCATIONS. HOWEVER...UPGRADE TO WARNING
MAY BE NEEDED.
SUN AND INTO MON...PERSISTENT WNW FLOW AND LAKE INDUCED WILL KEEP
LES GOING FOR THE WEST(NORTH OF M-28)AND EAST (EAST OF MUNISING)
WITH GRADUAL BACKING TREND ALLOWING LES BANDS TO LIFT OFFSHORE IN
THE EAST AND FOCUS INTO THE KEWEENAW. LIMITING FACTORS WITH
SNOWFLAKE GROWTH REMAIN. SO...OVERALL ACCUMULATIONS WILL MAINLY BE
IN THE 2-5 INCH PER 12 HOURS EAST AND 1-3 INCHES WEST. TEMPERATURES
ARE EXPECTED TO AGAIN FALL TO -10 TO -20 INLAND. LIGHTER WINDS BLO
10 MPH WILL KEEP WIND CHILL VALUES FROM BEING QUITE AS SEVERE.
&&
.AVIATION (FOR THE 12Z TAF ISSUANCE)...
PERSISTENCE IS THE WAY TO GO WITH THE TAF FORECAST THROUGH THE NEXT
24 HOURS AS THE PATTERN STAYS MAINLY THE SAME. BASICALLY...NORTHWEST
WINDS CONTINUE TO DRIVE ARCTIC AIR ACROSS LAKE SUPERIOR INTO UPPER
MICHIGAN...WHICH WILL HELP MAINTAIN LAKE EFFECT SNOW SHOWERS WITH
FINE SNOWFLAKES. THESE FINER SNOWFLAKES COMBINED WITH THE WIND HAVE
KEPT CMX BOUNCING BETWEEN LIFR AND IFR FOR VSBY...AND IFR TO MVFR
FOR CEILING FOR THE PAST 12 HOURS...AND THIS SHOULD CONTINUE THROUGH
TONIGHT. AT SAW...LAKE EFFECT BANDS OFF WESTERN LAKE SUPERIOR CANNOT
PENETRATE THAT FAR INLAND...THUS VFR CONDITIONS ARE FORECAST.
&&
.MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)...
A LOW PRESSURE TROUGH OVER EASTERN LAKE SUPERIOR WILL KEEP REMAIN
STATIONARY THROUGH MONDAY. W-NW FLOW WILL REMAIN IN THE 15 TO 30 KT
RANGE DURING THIS PERIOD...WITH THE STRONGEST WINDS OCCURRING TODAY
AND TONIGHT. A RIDGE OF HIGH PRESSURE WILL CROSS LAKE SUPERIOR
MONDAY NIGHT INTO TUESDAY...CAUSING WINDS TO BACK MORE TOWARDS THE
WEST...THOUGH SPEEDS REMAIN BETWEEN 15 AND 25 KT. A COLD FRONT
PASSAGE IS EXPECTED TUE NIGHT. BEHIND THIS FRONT...LOOK FOR WINDS TO
FALL BELOW 20 KT. HEAVY FREEZING SPRAY WILL CONTINUE THROUGH SUNDAY
NIGHT DUE TO THE STRONG WINDS AND PERSISTENT ARCTIC AIRMASS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
MICHIGAN...
  LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST SUNDAY
     FOR MIZ001>003.
  LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ085.
  LAKE EFFECT SNOW WARNING UNTIL 7 AM EST SUNDAY FOR MIZ006-007.
  WIND CHILL ADVISORY UNTIL 1 PM EST /12 PM CST/ SUNDAY FOR
     MIZ002-004-005-009>011-084.
LAKE SUPERIOR...
  HEAVY FREEZING SPRAY WARNING UNTIL 4 AM EST MONDAY LSZ162-263>267.
LAKE MICHIGAN...
  HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST SUNDAY
    LMZ221-248-250.
&&
$$
DISCUSSION...JLB
AVIATION/MARINE...AJ
</pre> mi
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
500 AM EST SAT JAN 19 2008
.DISCUSSION...
MAIN FCST CONCERNS ARE LES TRENDS ALONG WITH TEMPS/WIND CHILLS.
WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH
DOMINATING CNTRL AND ERN NOAM. ONE SHORTWAVE TROUGH EMBEDDED IN THE
CYCLONIC FLOW WAS MOVING THROUGH CNTRL UPPER MI. ANOTHER UPSTREAM
SHRTWV WAS LOCATED NE OF LAKE WINNIPEG. AT THE SFC...LAKE NW FLOW
PREVAILED BTWN ARCTIC HIGH PRES INTO THE PLAINS AND WEAK TROFFING
FROM QUEBEC INTO THE GREAT LAKES. LAKE INDUCED TROFFING WAS EVIDENT
ACROSS SRN LAKE SUPERIOR SUPPORTED BY VERY LARGE LAND/LAKE TEMP
DIFFERENCE. RADAR INDICATED THAT THE DOMINANT BAND INTO THE NE CWA
LAKE SUPERIOR SHORELINE HAD TRANSITIONED TO WEAKER MULTIPLE WIND
PARALLEL BANDS AS WINDS VEERED TO 320 CBL FLOW. OTHERWISE...VERY
COLD AIR HAS MOVED INTO THE REGION WITH TEMPS OVER NRN MN AND WRN
ONTARIO WITH 850 MB TEMPS AOB -30C. SFC TEMPS WERE INTO THE -20 TO -25
RANGE AND READINGS FROM AROUND ZERO NEAR LAKE SUPERIOR TO -15 BELOW
OVER INLAND PORTIONS OF WEST UPPER MI. THE COLD AIR ALONG WITH WINDS
OF 5 TO 15 MPH HAVE DROPPED WIND CHILL VALUES INTO THE ADVISORY
RANGE FROM -20 TO -35.
TODAY...EXPECT WINDS TO GRADUALLY BACK WITH THE APPROACH OF THE
MANITOBA SHORTWAVE. THE NAM AND LCL HIGH RES WRF/ARW THAT HAVE
HANDLED EFFECTS OF LAKE TROFFING REASONABLY WELL SUGGEST THAT
HEAVIER LES BANDS WILL AGAIN SHIFT CLOSER TO THE SHORELINE EAST OF
MUNISING IN THE ERN CWA. TEMP PROFILE...WITH ONLY A SHALLOW OR NO
LAYER ABOVE -17C WERE NOT FAVORABLE FOR DENDRITIC SNOWFLAKE GROWTH
AND SHOULD LIMIT ACCUMULATIONS...DESPITE VERY LARGE INSTABILITY (850
MB TEMPS TO AROUND -26C). HOWEVER...ACCUMULATIONS IN THE 3 TO 7 INCH
RANGE ARE STILL POSSIBLE. OVER THE WEST...THE SHORTER FETCH AND EVEN
COLDER/DRIER AIR WILL KEEP ACCUMULATIONS MAINLY IN THE 1 TO 4 INCH
RANGE. MDLS SHOW THE MOST FAVORABLE LOW LEVEL CONV BTWN
ONTONAGON...M-38 AND HOUGHTON. THE WINDS NEAR THE LAKE INTO THE 15
TO 25 MPH RANGE ALONG WITH THE FINE SNOWFLAKES WILL LIMIT VSBYS AT
TIMES TO AROUND 1/4SM. WIND CHILL VALUES WILL MODERATE WITH DIURNAL
WARMING BUT WILL STILL REMAIN CLOSE TO ADVISORY RANGE DURING THE
AFTERNOON FROM -15 TO -25.
TONIGHT...LOW LEVEL WINDS ARE EXPECTED TO VEER AGAIN THIS EVENING
IN THE WAKE OF THE MANITOBA SHORTWAVE. HOWEVER...THE COMBINATION OF
STRENGTHENING LAND BREEZES/LAKE INDUCED TROFFING AND THE APPROACH OF
ANOTHER SHRTWV WILL KEEP WINDS MAINLY FROM THE WNW. THE STRONGER LOW
LEVEL CONV WILL FOCUS MAINLY EAST OF MUNISING AND NEAR M-38.
ADDITIONAL AMOUNTS OF 2 TO 6 INCHES EAST AND 1 TO 3 INCHES WEST ARE
EXPECTED. AIDED BY LAKE TROFFING...THE GRADIENT WILL REMAIN STRONG
ENOUGH TONIGHT TO KEEP WINDS NEAR 10 MPH. COMBINED WITH TEMPS
FALLING INTO THE -5 TO -17 RANGE...WIND CHILL VALUES WILL AGAIN FALL
TO TH -25 TO -35 RANGE. SOME VALUES INTO THE WARNING RANGE ARE
POSSIBLE BUT MAY BE MARGINAL GIVEN BALANCE BETWEEN RADIATIONAL
COOLING/MIXING OVER INLAND LOCATIONS. HOWEVER...UPGRADE TO WARNING
MAY BE NEEDED.
SUN AND INTO MON...PERSISTENT WNW FLOW AND LAKE INDUCED WILL KEEP
LES GOING FOR THE WEST(NORTH OF M-28)AND EAST (EAST OF MUNSING) WITH
GRADUAL BACKING TREND ALLOWING LES BANDS TO LIFT OFFSHORE IN THE
EAST AND FOCUS INTO THE KEWEENAW. LIMITING FACTORS WITH SNOWFLAKE
GROWTH REMAIN. SO...OVERALL ACCUMULATIONS WILL MAINLY BE IN THE 2-5
INCH PER 12 HOURS EAST AND 1-3 INCHES WEST. TEMPERATURES ARE
EXPECTED TO AGAIN FALL TO -10 TO -20 INLAND. LIGHTER WINDS BLO 10
MPH WILL KEEP WIND CHILL VALUES FROM BEING QUITE AS SEVERE.
&&
.AVIATION (FOR THE 06Z TAF ISSUANCE)...
LIFR CONDITIONS CAN BE EXPECTED AT CMX THE REST OF TONIGHT WITH
BLOWING SNOW CAUSING VISIBILITY ISSUES AND THEN CONDITIONS SHOULD
IMPROVE A BIT TO IFR FOR VISIBILITY ON SAT AGAIN WITH BLOWING SNOW.
WINDS WILL INCREASE A BIT SAT EVENING AND VIS SHOULD GO DOWN AGAIN
TO LIFR WITH BLOWING SNOW.
FOR SAW...VFR CONDITIONS EXPECTED TO CONTINUE WITH W TO NW WINDS
KEEPING THE LAKE EFFECT BANDS WELL NORTH OF THE AREA. JUST A FEW
LAKE EFFECT CLOUDS OFF WESTERN LAKE SUPERIOR WILL CONTINUE TO AFFECT
THE SITE THROUGH THE PERIOD.
&&
.MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)...
A LOW PRESSURE TROUGH OVER EASTERN LAKE SUPERIOR WILL KEEP REMAIN
STATIONARY THROUGH MONDAY. W-NW FLOW WILL REMAIN IN THE 15 TO 30 KT
RANGE DURING THIS PERIOD...WITH THE STRONGEST WINDS OCCURRING TODAY
AND TONIGHT. A RIDGE OF HIGH PRESSURE WILL CROSS LAKE SUPERIOR
MONDAY NIGHT INTO TUESDAY...CAUSING WINDS TO BACK MORE TOWARDS THE
WEST...THOUGH SPEEDS REMAIN BETWEEN 15 AND 25 KT. A COLD FRONT
PASSAGE IS EXPECTED TUE NIGHT. BEHIND THIS FRONT...LOOK FOR WINDS TO
FALL BELOW 20 KT. HEAVY FREEZING SRPAY WILL CONTINUE THROUGH SUNDAY
NIGHT DUE TO THE STRONG WINDS AND PERSISTENT ARCTIC AIRMASS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
MICHIGAN...
  LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST SUNDAY
     FOR MIZ001>003.
  LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ085.
  LAKE EFFECT SNOW WARNING UNTIL 7 AM EST SUNDAY FOR MIZ006-007.
  WIND CHILL ADVISORY UNTIL 1 PM EST /12 PM CST/ SUNDAY FOR
     MIZ002-004-005-009>011-084.
LAKE SUPERIOR...
  HEAVY FREEZING SPRAY WARNING UNTIL 4 AM EST MONDAY LSZ162-263>267.
LAKE MICHIGAN...
  HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST SUNDAY
    LMZ221-248-250.
&&
$$
DISCUSSION...JLB
AVIATION/MARINE...AJ
</pre> mi
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
309 AM MST SUN JAN 20 2008
.SHORT TERM...VALID FOR TDY AND MON...
OVERALL THE CURRENT WINTER HEADLINES ARE IN GOOD SHAPE AND WILL
MAKE NO CHANGES. A COUPLE OF MODEL ERRORS WITH THIS EVENT ARE
BECOMING APPARENT. CIRCULATION IN NE WASHINGTON NOT INITIALLY
HANDLED BY MODELS WELL...AND IS A FOCUS FOR SOME PRETTY GOOD
ASCENT TO OUR WEST STILL. AS A RESULT WE ARE SEEING DIFFLUENT
SIGNATURE ON WATER VAPOR IMAGERY SPREAD INTO OUR AREA JUST NOW.
OTHER ERROR IS THAT THE MODELS WERE DRIVING THE COLD AIR SOUTH
INTO OUR AREA TOO QUICKLY. TEMPS HAVE NOT FALLEN AT ALL OVER THE
PAST FEW HOURS...AND IN FACT HAVE WARMED IN SOME CASES. THIS IN
RESPONSE TO INCREASING WARM ADVECTION AS STRONGER DYNAMICS NEAR
US. NAM/RUC SEEM TO HAVE DECENT HANDLE ON THESE ITEMS NOW...AND
SHOW PERIOD OF MID LEVEL WARM ADVECTION INTO OUR AREA EARLY THIS
MORNING. WITH THIS ALONG WITH DEEPENING DENDRITIC LAYER WOULD
EXPECT A FEW HOURS OF ENHANCED SNOWFALL THIS MORNING...RATES
POSSIBLY NEAR AN INCH PER HOUR FOR A SHORT TIME...STARTING ACROSS
CENTRAL PARTS INCLUDING BILLINGS THEN FINALLY PUSHING SOUTH TO THE
FOOTHILLS BY 15Z OR SO. INFRARED IMAGERY INDEED SHOWS COLDER TOPS
WORKING IN FROM THE WEST...IN LINE WITH THESE THOUGHTS. SO...HAVE
UPPED EXPECTED SNOW AMOUNTS TODAY TO GENERALLY 3 TO 5 INCHES FROM
BILLINGS SOUTHWARD. SLOWER NATURE OF SYSTEM SHOULD ALSO ALLOW FOR
WARM ADVECTION TO REACH OUR SE ZONES. HAVE RAISED POPS AND SNOW
AMOUNTS IN THIS AREA...FROM LAME DEER TO EKALAKA...AND SEE NO
REASON TO CHANGE CURRENT ADVISORY IN THIS AREA. WINDS GUSTING
PRETTY GOOD IN NOTORIOUS PLACES SUCH JUDITH GAP...LIVINGSTON AND
ABERDEEN HILL...AND BLOWING/DRIFTING SNOW IS NO DOUBT WREAKING
HAVOC ON AREA ROADS.
WILL CONTINUE THE HIGH POPS ACROSS OUR SOUTHERN TIER FOR
TONIGHT... BUT COLD AIR SHOULD FINALLY SURGE IN BEFORE THEN THUS
DIMINISHING THE SNOW RATIOS. NAM CONTINUES TO SHOW UPSLOPE LIGHT
PCPN CONTINUING INTO MON. GIVEN HOW THE SYSTEM HAS STALLED ALREADY
THINK EXPANDING SOME LOW POPS FOR LIGHT SNOW OR FLURRIES NOT A BAD
IDEA...AT LEAST FOR MON MORNING. SUBSIDENCE WITH UPPER RIDGE WILL
FINALLY DRY THINGS OUT ACROSS THE AREA LATE MON AND MON NITE.
WINDS NOT DOING MUCH AT BAKER...AND TEMPS JUST A BIT BELOW ZERO
ANYWAY... SO WILL CANCEL THE WIND CHILL ADVISORY FOR FALLON
COUNTY. SHOULD SEE SOME INCREASED WIND AS THE DAY GOES AS COLD
ADVECTION PICKS BACK UP. WIND CHILLS SHOULD STAY ABOVE CRITERIA
THOUGH UNTIL POSSIBLY TONIGHT. WILL LET DAY SHIFT MAKE THAT CALL.
NAM/GFS VERY DIFFERENT WITH REGARD TO WHEN SFC RIDGE WILL GIVE WAY
TO CHINOOKING. GFS BEGINS THE WSW WINDS DURING THE DAY ON MONDAY
WHEREAS THE NAM HOLDS IT OFF TIL MON NIGHT. HAVE WENT WITH A
COMPROMISE HERE...SIMILAR TO WHAT THE SREF SHOWS. EITHER WAY
SHOULD SEE WINDS LATE MON NITE INCREASE TO THE POINT THAT BLOWING
SNOW AND POSSIBLY WIND CHILLS WILL BE A CONCERN. HAVE PAINTED SOME
BLSN IN OUR WESTERN PARTS 06-12Z TUE.
AS FOR TEMPS...HAVE TWEAKED EXPECTED HIGHS UP A BIT TODAY. HIGHS
WILL BE ACHIEVED EARLY WITH FALLING TEMPS THEREAFTER. COLD NIGHT
TONIGHT BUT WITH CLOUD COVER AROUND THEY SHOULD NOT FALL TOO
FAR...GENERALLY 5 TO 15 BELOW. HAVE LOWERED EXPECTED HIGHS A BIT
MON AS COLDEST AIR WILL BE RIGHT OVER US...AGAIN A COMPROMISE
BETWEEN THE NAM AND GFS HERE...HIGHS MAINLY SINGLE DIGITS.
JKL
.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...
AS THE WEEKEND SYSTEM PUSHES SOUTH OF THE AREA TUESDAY WILL SEE A
NORTHERLY FLOW ALOFT MOVE INTO MONTANA. A CLIPPER MOVING RAPIDLY
SOUTHWARD IN THIS FLOW WILL BRING A REVERSAL TO DOWNSLOPE WINDS
EARLY ON TUESDAY WITH CONCERNS FOR BLOWING SNOW FROM BILLINGS WEST
AS LOTS OF NEW POWDERY SNOW WILL COVER THE AREA. TEMPERATURES WILL
MODERATE WITH THE DOWNSLOPE BUT GIVEN SO MUCH SNOW TEMPERATURES
WILL BE TRICKY. THE CLIPPER MOVES INTO THE DAKOTAS AND EASTERN
MONTANA TUESDAY NIGHT AND AMPLIFIES THE CYCLONIC FLOW ALOFT
BRINGING A RISK FOR ADDITIONAL SNOWFALL. COLD AIR REINFORCES A BIT
BEHIND THE SYSTEM BUT CLOUD COVER SHOULD KEEP TUESDAY NIGHT TEMPS
FROM BEING TOO COLD. WEDNESDAY AND THURSDAY LOOK DRY AND STABLE
WITH WEAK DOWNSLOPE RESIDENT THROUGH THE PERIOD. HOW FAR EAST THE
DOWNSLOPE PLAYS A ROLE WILL BE A BIG FACTOR IN HOW MUCH MODERATION
OCCURS WITH EASTERN MONTANA LIKELY STAYING IN THE CHILL. FOR
FRIDAY THE REMNANTS OF THE WEEKEND STORM SYSTEM THAT SLID ACROSS
NORTHERN CALIFORNIA BEGINS TO EJECT IN A SOUTHWESTERLY FLOW ALOFT
ACROSS THE AREA. THIS WILL TURN THE FLOW ALOFT CYCLONIC BUT MAIN
FORCING LOOKS TO BE SOUTH AND WEST OF MONTANA. MODELS DO PROG WEAK
CYCLOGENESIS ACROSS THE AREA WHICH COULD BRING A PERIOD OF SNOW
BUT MODELS ARE NOT IN AGREEMENT TO THE DEPTH OF THIS SYSTEM SO
CONFIDENCE AT THIS POINT IS LOW. STRONGER SYSTEM MOVES ACROSS THE
EASTERN PACIFIC TO THE GULF OF ALASKA FOR NEXT WEEKEND WITH A
STRONG FLOW ALOFT INTO THE PACIFIC NORTHWEST. THIS WILL BRING AN
OROGRAPHIC PRECIPITATION PATTERN FOR THE MOUNTAINS AND STRONGER
DOWNSLOPING AND MODERATIONS. BORSUM
&&
.AVIATION...
SNOW WILL CONTINUE ACROSS MOST OF THE AREA INTO SUNDAY NIGHT.
PORTIONS OF SOUTHEAST MONTANA WILL SEE SLIGHTLY BETTER
CONDITIONS...BUT THE REMAINDER OF THE AREA WILL SEE IFR TO LIFR
CONDITIONS UNTIL SUNDAY EVENING. BORSUM
&&
.PRELIMINARY POINT TEMP/POPS...
    TDY MON     TUE     WED     THU     FRI     SAT
-------------------------------------------------------
BIL 013 905/005 904/019 010/022 013/026 012/030 017/029
    +/S 91/M    00/Q    30/B    00/N    11/B    22/S
LVM 013 908/003 907/020 007/025 016/029 017/030 023/028
    +/S 92/S    01/Q    30/B    00/N    21/B    23/S
HDN 013 906/005 908/018 006/022 008/022 007/028 012/029
    +/S 81/M    00/Q    40/B    00/B    11/B    21/B
MLS 012 913/005 910/016 003/016 004/024 004/025 008/026
    4/S 20/U    03/S    30/B    00/B    11/B    11/B
4BQ 011 910/004 914/018 002/019 003/023 003/024 007/026
    9/S 71/M    00/B    30/B    00/B    11/B    11/B
BHK 007 918/001 914/013 901/016 000/020 001/023 005/025
    2/S 20/U    02/S    30/B    00/B    11/B    12/S
SHR 015 905/004 911/015 002/021 005/024 005/026 009/026
    +/S +3/S    00/B    41/M    00/B    11/B    22/S
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WARNING IN EFFECT UNTIL 11 PM MST THIS EVENING
      FOR ZONES 28-29-34-35-40>42-57-63-68.
     SNOW AND BLOWING SNOW ADVISORY IN EFFECT UNTIL 5 PM MST THIS
      AFTERNOON FOR ZONES 30>32-36-37-58.
     WINTER STORM WARNING IN EFFECT UNTIL 5 AM MST MONDAY FOR
      ZONES 38-39-56-64>67.
WY...WINTER STORM WARNING IN EFFECT UNTIL 5 AM MST MONDAY FOR
      ZONES 98-99.
&&
$$
WEATHER.GOV/BILLINGS
</pre> mt
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
1015 AM EST SAT JAN 19 2008
.SYNOPSIS...
LOW PRESSURE ACROSS THE NORTHERN GULF OF MEXICO WILL MOVE OFF THE
SOUTHEAST UNITED STATES COAST TODAY. THE LOW WILL INTENSIFY AS IT
MOVES RAPIDLY TO THE NORTHEAST ACROSS THE OFFSHORE WATERS OF THE
CAROLINAS BY THIS EVENING. ARCTIC HIGH PRESSURE WILL BUILD INTO THE
CAROLINAS SUNDAY THROUGH MONDAY. A COASTAL TROUGH MAY DEVELOP
OFFSHORE ON TUESDAY BEFORE BEING SWEPT AWAY BY A STRONG COLD FRONT
TUESDAY NIGHT. HIGH PRESSURE TO BUILD IN FOR WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 10 AM SATURDAY...ISENTROPIC LIFT LEADING TO A WIDESPREAD AREA
OF RAINFALL ACROSS THE REGION THIS MORNING. LOW PRESSURE IS MOVING
INTO THE NE GULF OF MEXICO AND WILL CONTINUE TO LIFT NE TO OFF THE
SE STATES THIS AFTERNOON. THE LOW WILL PULL AWAY FROM THE AREA THIS
EVENING...THEN CHANCES FOR PRECIPITATION WILL DIMINISH FROM W TO E
ACROSS THE AREA. PRECIP WILL LIKELY COME TO AN END BY MIDNIGHT
INLAND...AND A COUPLE HOURS LATER ALONG THE COAST. THE POTENTIAL
CONTINUES FOR A MIX OF PRECIPITATION...POSSIBLY CHANGING TO ALL SNOW
AS THE PRECIP SHIELD EXITS THE AREA. PLAN TO CONTINUE WITH THE
WINTER WEATHER ADVISORY ACROSS THE NORTHWESTERN TIER ZONES WHERE
THERE IS A HIGHER CHANCE OF SEEING ACCUMULATING SNOW (UP TO AN
INCH). COULD SEE SOME TRACE AMOUNTS FARTHER E AS THE PRECIP EXITS.
COLD TEMPERATURES WILL SPREAD ACROSS THE FORECAST AREA OVERNIGHT AND
ANY RESIDUAL MOISTURE ON THE ROADWAYS MAY CREATE SLICK CONDITIONS
INTO SUNDAY MORNING.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...ARCTIC AIR MASS BUILDS IN SUN AS SFC CYCLONE
MOVING AWAY FROM THE REGION DEEPENS AND DEEP UPPER TROF SWINGS
THROUGH. 1000-500 THICKNESS VALUES DROP INTO THE 520S AND 850 TEMPS
DROP BELOW -10. UPPER PATTERN QUICKLY BECOMES ZONAL WITH SFC HIGH
MOVING OFFSHORE LATE SUN INTO MON AND RETURN FLOW STARTING MON
NIGHT.
TEMPERATURES WILL REMAIN WELL BELOW CLIMO...STRUGGLING TO REACH 40
ON SUN AND FALLING INTO THE TEENS/LOW 20S SUN NIGHT. SLIGHT WARM UP
ON MON...WITH TEMPS BARELY HITTING 40...THOUGH PARTIAL THICKNESS
VALUES SUGGEST TEMPS MAY NOT MAKE IT TO 40 IN MANY AREAS. TEMPS
START TO REBOUND MON NIGHT AS SRLY FLOW STARTS TO DEVELOP AND
COASTAL TROF BEGINS TAKING SHAPE. INCREASING CLOUD COVER MON NIGHT
WILL HELP KEEP TEMPS CLOSE TO CLIMO.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 3 AM SATURDAY...WEAK WARM AIR ADVECTION ON TUESDAY AHEAD OF A
COLD FRONT SHOULD BRING TEMPS TO OR SLITELY ABOVE NORMAL. THAT MAY
BECOME THE WARMEST DAY OF THE EXTENDED PERIOD WITH THE MAJORITY OF
THE LONG TERM FEATURING TEMPS BELOW NORMAL WITH THE LATEST MEX MOS
GUIDANCE HOT OFF THE PRESS ILLUSTRATING THIS.
VERY ACTIVE WEEK AND PROGRESSIVE PATTERN CONTINUES. GFS MODEL SEEMS
OVERZEALOUS WITH MOISTURE WITH THE COLD FRONT ON TUESDAY AND AS A
RESULT WILL STAY ON THE LOW CHANCE SIDE FOR PRECIP. BRIEF REPRIEVE
ON WEDNESDAY B4 NEXT PCPN EVENT. WED NITE INTO THU NIGHT FEATURES AN
OVERRUNING TYPE EVENT WITH LOW PRESSURE FROM THE GULF MOVING NE
ALONG THE OLD FRONTAL BOUNDARY FROM TUESDAY...TO OFF THE CAROLINA
COASTS BY LATE THURSDAY NIGHT. COULD BE INTERESTING WITH RESPECT TO
FREEZING AND FROZEN PCPN IF ENUF COLD AIR GETS PULLED INTO THE
SYSTEM. RIGHT NOW ITS AN ALL RAIN EVENT GIVEN LATEST THICKNESS
SCHEMES ACROSS THE AREA. HAVE GONE WITH ANOTHER BRIEF REPRIEVE ON
FRIDAY WITH CAA BEHIND THE DEPARTING LOW ACROSS THE AREA. SATURDAY
WILL FEATURE ANOTHER CHANCE FOR PCPN.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
SOUTHERN STREAM VORT PULLING UP MOISTURE FROM THE GULF WELL AHEAD OF
IT. VIA RUC AND WATER VAPOR...THE VORT IS ENTERING THE WESTERN GULF
AT THE MOMENT. SFC LOW CONTINUES TO DEVELOP IN THE CENTRAL GULF
AHEAD OF THE UPPER VORT. EXPECT OVERRUNING PCPN TO AFFECT THE AREA
TERMINALS...COMMENCING WITH THE INLAND TERMINALS 1ST BY 13Z...THEN
THE COASTAL ONES BY 15Z. IFR AND LIFR CONDITIONS WILL BECOME
PREDOMINATE AFTER 15Z AND LAST ROUGHLY THRU 07Z SUNDAY. THE HEAVIEST
RAIN WILL OCCUR BETWEEN 17Z AND 22Z SATURDAY WHERE MODERATE RAIN HAS
BEEN TEMPO`D. OVERALL...WINDS WILL REMAIN N-NNE...360-030...THRUOUT
THE DAY AT SPEEDS AROUND 10 KT. THEN BEGIN TO BACK THIS EVENING AND
OVERNITE AS THE SFC LOW PASSES EAST OF THE AREA...ALLOWING SOME
COLDER AIR TO WORK ITS WAY INTO THE AREA. THE INLAND TERMINALS WILL
LIKELY OBSERVE IP AND SN MIXING WITH THE RAIN DURING THE EVENING AND
OVERNIGHT...WITH PCPN POSSIBLY BECOMING ALL SNOW PRIOR TO ENDING
ESPECIALLY ACROSS LBT.
VFR CONDITIONS SUNDAY AND MONDAY. A WEAK SYSTEM WILL APPROACH THE
AREA TUESDAY...WITH IFR CONDITIONS POSSIBLE TUESDAY NIGHT INTO
WEDNESDAY MORNING.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 10 AM SATURDAY...WAVE HEIGHTS ARE INCREASING THIS MORNING AS
THE NORTHERLY PRESSURE GRADIENT TIGHTENS. THE LOW IS MOVING INTO THE
NE GULF OF MEXICO AND WILL QUICKLY MOVE NE OFF THE SE COAST THROUGH
THE AFTERNOON AND EVENING. COLD AIR ADVECTION IN THE WAKE OF THE LOW
WILL SUPPORT STRONGER OFFSHORE FLOW THROUGH THE EVENING. NO CHANGES
NEEDED TO THE SMALL CRAFT ADVISORY.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM SATURDAY...SUNDAY TO FEATURE ARCTIC AIR ADVECTING ACROSS
THE COASTAL WATERS...WITH SPEEDS AROUND 25 KT AND GUSTS UP TO 30 KT.
WOULD NOT BE SURPRISED TO C A FEW GUSTS UP TO 35 KT EARLIER IN THE
DAY. HAVE OUTLINED A RANGE OF SEAS ACROSS THE WATERS DUE TO THE NW
TO N OFFSHORE TRAJECTORY. SEAS AND WINDS WILL DROP BELOW SCA
CONDITIONS DURING THE MID-AFTERNOON HOURS AS THE CENTER OF THE SFC
HIGH APPROACHES FROM THE WEST CAUSING THE SFC TO RELAX SOME ACROSS
THE IMMEDIATE COASTAL WATERS. MODELS HAVE INDICATED THE CENTER OF
THE SFC HIGH PASSING OFF THE CENTRAL NC COAST MONDAY...AND WELL
OFFSHORE MONDAY NIGHT. THIS WILL CAUSE WINDS TO VEER TO THE
NE...WITH MODELS HAVING INDICATED THE DEVELOPMENT OF AN INVERTED SFC
TROF OFF THE CAROLINA COASTS BY MON NITE. THE SFC PG TO BECOME
TIGHTENED BY LATE MONDAY ESPECIALLY OVER THE SOUTHERN WATERS AND
WILL RESULT IN WIND SPEEDS ATLEAST IN THE 15-20 KT
RANGE...ESPECIALLY THE SOUTHERN WATERS.
LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 3 AM SATURDAY...TUESDAY WILL FEATURE THE BREAKDOWN OF THE
WEDGE AND THE COASTAL TROF WITH NE WINDS BECOMING S OR SW AHEAD OF
THE APPROACH OF A COLD FRONT. MODELS SEEM A BIT HIGH ON WAA WIND
SPEEDS ACROSS THE COLDER SSTS OF THE ILM COASTAL WATERS AND WOULD
LIKE TO LOWER THEM SOME. HAVE DONE THE SAME WITH SEAS WITH WINDS
VEERING TO THE WEST LATER IN THE DAY WHICH WILL ALSO AID IN KNOCKING
THEM DOWN. CFP SLATED FOR TUE NITE...ENDING THE THREAT FOR
PCPN...WITH NW WINDS PICKING UP TO 15 TO 20 KT WITH RANGE OF SEAS
EXPECTED ACROSS THE WATERS.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM EST
     SUNDAY FOR SCZ017-023-024.
NC...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM EST
     SUNDAY FOR NCZ087-096.
MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 2 PM
     EST SUNDAY FOR AMZ250-252-254-256.
&&
$$
SYNOPSIS...SRP
NEAR TERM...SRP
SHORT TERM...III/DCH
LONG TERM...DCH
AVIATION...DCH
</pre> nc
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
645 AM EST SAT JAN 19 2008
.SYNOPSIS...
LOW PRESSURE IN THE WESTERN GULF OF MEXICO WILL MOVE OFF THE
SOUTHEAST UNITED STATES COAST THIS MORNING. THE LOW WILL INTENSIFY
AS IT MOVES RAPIDLY TO THE NORTHEAST ACROSS THE OFFSHORE WATERS OF
THE CAROLINAS BY SATURDAY EVENING. ARCTIC HIGH PRESSURE WILL BUILD
INTO THE CAROLINAS SUNDAY THROUGH MONDAY. A COASTAL TROUGH MAY
DEVELOP OFFSHORE ON TUESDAY BEFORE BEING SWEPT AWAY BY A STRONG COLD
FRONT TUESDAY NIGHT. HIGH PRESSURE TO BUILD IN FOR WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 3 AM THIS MORNING...NO QUESTION...RAIN WILL OCCUR TODAY AND
QPFS IN MOST ARE WILL BE ABOVE 1". BIGGEST FORECAST MYSTERY REMAINS
HOW PRECIP ENDS OVERNIGHT. LATEST SOUNDINGS SHOW AN ENVIRONMENT THAT
WOULD PROMOTE A SLEET/RAIN MIX THAT CHANGES OVER TO MOSTLY OR ALL
SNOW AS IT ENDS. WHILE SOUNDINGS DROP BELOW FREEZING THROUGH ALL
LAYERS...ESPECIALLY INLAND...THERE IS STILL SOME QUESTION AS TO
IF/WHEN CHANGE TO FROZEN WILL OCCUR. TEMPS THROUGH THE LAYER DO NOT
DROP MUCH BELOW FREEZING SO SLEET COULD END UP BEING MORE PREVALENT
THAN SNOW.
GFS IS SHOWING STRONG FRONTOGENESIS OVER INLAND ILM COUNTIES WHICH
COULD RESULT IN SOME BANDING OF PRECIP. HAVE DECIDED TO RAISE A
WINTER WX ADVISORY FOR INLAND MOST COUNTIES...BUT WILL STOP SHORT OF
GOING WITH A WARNING(2"). SEVERAL FACTORS SHOULD HELP KEEP
SNOW/SLEET AMOUNTS UNDER 2" FOR THIS EVENT. FIRST...GROUND
TEMPS...AS WELL AS THE BOUNDARY LAYER...REMAIN ABOVE FREEING THROUGH
THE EVENT. ANOTHER MITIGATING FACTOR IS THE FACT THAT SNOW THAT DOES
FALL WILL BE EXTREMELY WET AND HEAVY AND LESS LIKELY TO ACCUMULATE
TO WARNING CRITERIA.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 AM THIS MORNING...ARCTIC AIR MASS BUILDS IN SUN AS SFC
CYCLONE MOVING AWAY FROM THE REGION DEEPENS AND DEEP UPPER TROF
SWINGS THROUGH. 1000-500 THICKNESS VALUES DROP INTO THE 520S AND 850
TEMPS DROP BELOW -10. UPPER PATTERN QUICKLY BECOMES ZONAL WITH SFC
HIGH MOVING OFFSHORE LATE SUN INTO MON AND RETURN FLOW STARTING MON
NIGHT.
TEMPERATURES WILL REMAIN WELL BELOW CLIMO...STRUGGLING TO REACH 40
ON SUN AND FALLING INTO THE TEENS/LOW 20S SUN NIGHT. SLIGHT WARM UP
ON MON...WITH TEMPS BARELY HITTING 40...THOUGH PARTIAL THICKNESS
VALUES SUGGEST TEMPS MAY NOT MAKE IT TO 40 IN MANY AREAS. TEMPS
START TO REBOUND MON NIGHT AS SRLY FLOW STARTS TO DEVELOP AND
COASTAL TROF BEGINS TAKING SHAPE. INCREASING CLOUD COVER MON NIGHT
WILL HELP KEEP TEMPS CLOSE TO CLIMO.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 3 AM FRIDAY...WEAK WARM AIR ADVECTION ON TUESDAY AHEAD OF A
COLD FRONT SHOULD BRING TEMPS TO OR SLITELY ABOVE NORMAL. THAT MAY
BECOME THE WARMEST DAY OF THE EXTENDED PERIOD WITH THE MAJORITY OF
THE LONG TERM FEATURING TEMPS BELOW NORMAL WITH THE LATEST MEX MOS
GUIDANCE HOT OFF THE PRESS ILLUSTRATING THIS.
VERY ACTIVE WEEK AND PROGRESSIVE PATTERN CONTINUES. GFS MODEL SEEMS
OVERZEALOUS WITH MOISTURE WITH THE COLD FRONT ON TUESDAY AND AS A
RESULT WILL STAY ON THE LOW CHANCE SIDE FOR PRECIP. BRIEF REPRIEVE
ON WEDNESDAY B4 NEXT PCPN EVENT. WED NITE INTO THU NIGHT FEATURES AN
OVERRUNING TYPE EVENT WITH LOW PRESSURE FROM THE GULF MOVING NE
ALONG THE OLD FRONTAL BOUNDARY FROM TUESDAY...TO OFF THE CAROLINA
COASTS BY LATE THURSDAY NIGHT. COULD BE INTERESTING WITH RESPECT TO
FREEZING AND FROZEN PCPN IF ENUF COLD AIR GETS PULLED INTO THE
SYSTEM. RIGHT NOW ITS AN ALL RAIN EVENT GIVEN LATEST THICKNESS
SCHEMES ACROSS THE AREA. HAVE GONE WITH ANOTHER BRIEF REPRIEVE ON
FRIDAY WITH CAA BEHIND THE DEPARTING LOW ACROSS THE AREA. SATURDAY
WILL FEATURE ANOTHER CHANCE FOR PCPN.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
SOUTHERN STREAM VORT PULLING UP MOISTURE FROM THE GULF WELL AHEAD OF
IT. VIA RUC AND WATER VAPOR...THE VORT IS ENTERING THE WESTERN GULF
AT THE MOMENT. SFC LOW CONTINUES TO DEVELOP IN THE CENTRAL GULF
AHEAD OF THE UPPER VORT. EXPECT OVERRUNING PCPN TO AFFECT THE AREA
TERMINALS...COMMENCING WITH THE INLAND TERMINALS 1ST BY 13Z...THEN
THE COASTAL ONES BY 15Z. IFR AND LIFR CONDITIONS WILL BECOME
PREDOMINATE AFTER 15Z AND LAST ROUGHLY THRU 07Z SUNDAY. THE HEAVIEST
RAIN WILL OCCUR BETWEEN 17Z AND 22Z SATURDAY WHERE MODERATE RAIN HAS
BEEN TEMPO`D. OVERALL...WINDS WILL REMAIN N-NNE...360-030...THRUOUT
THE DAY AT SPEEDS AROUND 10 KT. THEN BEGIN TO BACK THIS EVENING AND
OVERNITE AS THE SFC LOW PASSES EAST OF THE AREA...ALLOWING SOME
COLDER AIR TO WORK ITS WAY INTO THE AREA. THE INLAND TERMINAS WILL
LIKELY OBSERVE IP AND SN MIXING WITH THE RAIN DURING THE EVENING AND
OVERNIGHT...WITH PCPN POSSIBLY BECOMING ALL SNOW PRIOR TO ENDING
ESPECIALLY ACROSS LBT.
VFR CONDITIONS SUNDAY AND MONDAY. A WEAK SYSTEM WILL APPROACH THE
AREA TUESDAY...WITH IFR CONDITIONS POSSIBLE TUESDAY NIGHT INTO
WEDNESDAY MORNING.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 AM THIS MORNING...NRLY FLOW TODAY WILL BEGIN INCREASING AS
LOW PRESSURE IN THE NRN GOMEX CROSSES FL AND MOVES UP THE E COAST.
GRADIENT WILL TIGHTEN AS LOW DEEPENS...WITH SPEEDS LIKELY EXCEEDING
25 KT LATE TONIGHT. GOING WITH SCA FOR ALL ZONES STARTING TONIGHT
AND LASTING THROUGH THE PERIOD. OFFSHORE COMPONENT OF WINDS WILL
KEEP SEAS WITHIN 20 NM AT OR BELOW 6 FT. STRONG COLD ADVECTION IN
THE WAKE OF THE SYSTEM MAY ADD A LITTLE TO SFC WINDS...BUT COOLER
SHELF WATERS WILL PREVENT STRONGEST WINDS FROM MIXING TO THE SURFACE.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
SUNDAY TO FEATURE ARCTIC AIR ADVECTING ACROSS THE COASTAL
WATERS...WITH SPEEDS AROUND 25 KT AND GUSTS UP TO 30 KT. WOULD NOT
BE SURPISED TO C A FEW GUSTS UP TO 35 KT EARLIER IN THE DAY. HAVE
OUTLINED A RANGE OF SEAS ACROSS THE WATERS DUE TO THE NW TO N
OFFSHORE TRAJECTORY. SEAS AND WINDS WILL DROP BELOW SCA CONDITIONS
DURING THE MID-AFTERNOON HOURS AS THE CENTER OF THE SFC HIGH
APPROACHES FROM THE WEST CAUSING THE SFC TO RELAX SOME ACROSS THE
IMMEDIATE COASTAL WATERS. MODELS HAVE INDICATED THE CENTER OF THE
SFC HIGH PASSING OFF THE CENTRAL NC COAST MONDAY...AND WELL OFFSHORE
MONDAY NIGHT. THIS WILL CAUSE WINDS TO VEER TO THE NE...WITH MODELS
HAVING INDICATED THE DEVELOPMENT OF AN INVERTED SFC TROF OFF THE
CAROLINA COASTS BY MON NITE. THE SFC PG TO BECOME TIGHTENED BY LATE
MONDAY ESPECIALLY OVER THE SOUTHERN WATERS AND WILL RESULT IN WIND
SPEEDS ATLEAST IN THE 15-20 KT RANGE...ESPECIALLY THE SOUTHERN
WATERS.
LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 3AM SATURDAY...TUESDAY WILL FEATURE THE BREAKDOWN OF THE WEDGE
AND THE COASTAL TROF WITH NE WINDS BECOMING S OR SW AHEAD OF THE
APPROACH OF A COLD FRONT. MODELS SEEM A BIT HIGH ON WAA WIND SPEEDS
ACROSS THE COLDER SSTS OF THE ILM COASTAL WATERS AND WOULD LIKE TO
LOWER THEM SOME. HAVE DONE THE SAME WITH SEAS WITH WINDS VEERING
TO THE WEST LATER IN THE DAY WHICH WILL ALSO AID IN KNOCKING THEM
DOWN. CFP SLATED FOR TUE NITE...ENDING THE THREAT FOR PCPN...WITH NW
WINDS PICKING UP TO 15 TO 20 KT WITH RANGE OF SEAS EXPECTED ACROSS
THE WATERS.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM EST
     SUNDAY FOR SCZ017-023-024.
NC...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM EST
     SUNDAY FOR NCZ087-096.
MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 2 PM EST
     SUNDAY FOR AMZ254-256.
     SMALL CRAFT ADVISORY FROM 1 AM TO 2 PM EST SUNDAY FOR AMZ250-
     252.
&&
$$
SYNOPSIS...REK/DCH
NEAR TERM...III
SHORT TERM...III/DCH
LONG TERM...DCH
AVIATION...DCH
</pre> nc
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
840 PM CST SUN JAN 20 2008
.DISCUSSION...
FORECAST CHALLENGE FOR UPDATE WILL BE CLOUD TRENDS AND TEMPERATURES.
MID LEVEL SHEAR AXIS FROM HUDSON BAY SE TO CENTRAL ROCKIES CONTINUES
TO SAG SOUTHWARD PUTTING FA IN GENERAL MID LEVEL WESTERLY FLOW. MID
AND UPPER LEVEL CLOUDS CONTINUE TO PUSH EASTWARD ACROSS FA AHEAD OF
CENTRAL/NORTHERN ROCKIES SYSTEM. AREAS EAST OF VALLEY REGION HAVE
BEEN LAST TO SEE CLOUDS AND CURRENT TEMPERATURES RUNNING CLOSE TO
THIS TIME YSTDY. FARTHER WEST CLOUDS HAVE PUT A DAMPER ON COOLING.
WITH CIGS CLEAR BACK INTO MT CLOUDS LIKELY TO IMPACT REGION MOST OF
NIGHT. EASTERN AREAS SHOULD EVENTUALLY GET INTO CLOUDS WHICH SHOULD
LIMIT ADDITIONAL DROP. SOME CLEARING OVER NW ND AND RUC DOES SHOW
SOME DRYING THIS AREA LATER TONIGHT SO DVL BASIN MAY BE ABLE TO DROP
MORE LATE TONIGHT. WILL MAKE SOME ADJUSTMENTS TO TEMPERATURE OVER
AREAS EXPECTED TO BE IN CLOUDS MOST OF NIGHT MAINLY VALLEY WEST
SOUTH OF HIGHWAY 2.  WILL IN TURN INCREASE CLOUDS IN GRIDS OTHERWISE
MINIMAL ADDITIONAL CHANGES PLANNED.
&&
.AVIATION...VFR MID LEVEL CIGS WILL CONTINUE TO ADVANCE ACROSS FA.
AT THIS POINT LOOKING AT UPSTREAM CIGS NOT ANTICIPATING ANY CIGS BLO
4K FT.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
VOELKER
</pre> nd
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
1030 AM CST SUN JAN 20 2008
.DISCUSSION...
ECMWF WAS FASTER THAN THE NAM AND THE GFS. THE GFS WAS THE SLOWEST
OF THE THREE MODELS AT 84 HOURS. GFS AND RUC HANDLED THE CURRENT LOW
LEVEL WIND FIELDS BEST FROM THE VAD WINDS. NAM AND GFS WERE A BIT
WARM AT 925 HPA COMPARED TO TAMDAR SOUNDINGS. MODELS DID A BETTER
JOB AT 850 HPA WITH THE SLIGHTLY COOLER GFS CLOSER TO OBSERVED. WILL
USE THE GFS.
FOG LOOP/SURFACE OBS SHOW CLOUD DECK AROUND 9 THOUSAND FEET HAS
ENTERED WESTERN ZONES. CLOUD DECK EXTENDED INTO SOUTHERN SK. DECK
WAS MOVING TO THE SOUTHEAST BUT APPEARS TO BE DISSIPATING ON THE
EASTERN EDGE. POCKET OF MOISTURE AT 700 HPA ON GFS APPEARS TO BE
HANDLED WELL. TEMPERATURES HAVE NOT RECOVERED MUCH UNDER CLOUD DECK.
BOTH RUC AND GFS HAS BEST SUBSIDENCE OVER THE VALLEY AND MAY
DISSIPATING EAST EDGE OF CLOUD DECK. WILL CHECK ZONES.
&&
.PREVIOUS DISCUSSION /ISSUED 346 AM SUN JAN 20 2008/...
KEY CHALLENGE FOR TONIGHT WILL BE CLOUD COVER AND IMPACTS ON
TEMPERATURES IN THE DEVILS LAKE BASIN AND FAR WESTERN PORTION OF
THE FA. MID AND HIGH CLOUDS SLOWLY DRIFTING EASTWARD INTO EASTERN
ND. TEMPS HAD ALREADY PLUMMETED INTO THE NEG 20S BEFORE CLOUD DECK
MOVED IN...SO DO NOT SEE MUCH IMPACT ON TEMPS.
HIGH PRESSURE WILL CONTINUE TO DOMINATE WX PATTERN SUNDAY AND MONDAY...
WITH ARCTIC AIRMASS REMAINING IN PLACE AND KEEPING DAYTIME HIGHS BELOW
ZERO FOR ALL BUT THE SOUTHERN EDGE OF THE FA. WINDS WILL BE LESS
THAN 10 MPH...SO WIND CHILL ADVISORY WILL NOT BE REQUIRED.
NEXT CHALLENGE WILL BE TIMING OF CLIPPER MOVING THROUGH TUE
AFTERNOON AND NIGHT. GFS MUCH QUICKER WITH SYSTEM THAN THE
NAM...AND HAS SPED UP TIMING OF LOW OVER LAST TWO RUNS. TENDING
TOWARD FASTER GFS SOLUTION...BUT NOT AS AGGRESSIVE ON TIMING OF
PRECIP IN THE 12Z TO 18Z TUE TIME FRAME. DID INTRODUCE A CHANCE FOR
TUE AFTERNOON AND UPPED TUE NIGHT TO CHANCE POPS. OVERALL NOT A
TREMENDOUS AMOUNT OF MOISTURE WITH SYSTEM AND ATTM LOOKING FOR NO
MORE THAN A HALF INCH SNOW ACCUMULATION.
LITTLE CHANGES MADE TO FORECAST BEYOND DAY FOUR.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
HOPPES
</pre> nd
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1115 AM CST SUN JAN 20 2008
.DISCUSSION...
SNOW BAND SO FAR REMAINING JUST SOUTH OF OUR CWA BORDER...AND
APPEARS TO HAVE SET UP NEAREST BAND OF 850-800MB FRONTOGENESIS BASED
ON RUC13. SOME MID LEVEL DEVELOPMENT TRYING TO NUDGE NORTH WITH
800-750MB FRONTOGENESIS AREA...THOUGH THIS AREA WILL HAVE TO FIGHT
QUITE A DEEP LAYER OF DRY AIR AS IT CONTINUES TO PROGRESS NORTHEAST
THROUGH THE AFTERNOON. FOR TODAY...HAVE SLOWED DEVELOPMENT INTO FAR
SOUTHERN AREAS OF THE CWA...AND SCALED BACK POPS ALONG THE NORTHEAST
EDGE OF THE PRECIP AREA BASED ON SIMILAR EVOLUTION TO RH LEVELS
BELOW 800MB ON BOTH RUC AND NAM MODELS. THIS KEEPS EVEN SLIGHT CHC
POPS ROUGHLY SOUTHWEST OF A KHON-KFSD-KSPW LINE THROUGH 00Z.
WITH FRONTAL BOUNDARY ACTING AS PRIMARY FORCING MECHANISM FOR SNOW
AND INFLUX OF DRY LOW LEVEL AIR FROM THE SURFACE HIGH MOVING THROUGH
NORTHERN MINNESOTA...EXPECT A FAIRLY SHARP CUTOFF ALONG NORTHERN
EDGE OF SNOW. STILL HAVE TO EVALUATE NEW MODELS IN MORE DETAIL
BEFORE MAKING SIGNIFICANT CHANGES TO OVERNIGHT/EARLY MONDAY. HOWEVER
AT FIRST GLANCE LOOKS LIKE NAM TRIES TO EXPAND SOME HEAVIER PRECIP
TOO FAR NORTH OF AFOREMENTIONED KEY FRONTAL LAYER BETWEEN 850-750MB.
BOTH NAM AND RUC...AND TO SOME DEGREE GFS /THOUGH HARDER TO DISCERN
AT COARSER RESOLUTION/ SHOW A WEAK OFFSHOOT OF FRONTOGENESIS LIFT
NORTHEAST AHEAD OF THE MAIN BAND DURING THE LATE AFTERNOON/EVENING.
DO NOT THINK THIS WILL BE ABLE TO OVERCOME THE DRY AIR BY ITSELF...
BUT COULD AID TOP-DOWN SATURATION ENOUGH FOR MAIN FRONTAL BOUNDARY
WOULD BE ABLE TO PRODUCE SOME LIGHT PRECIP INTO THE FAR NORTH LATER
TONIGHT. FOR NOW...BASED ON QUICK LOOK AT GFS AND NAM...WILL LET
ADVISORY AREA RIDE AS IS...BUT MAY HAVE TO REFINE A LITTLE MORE THIS
AFTERNOON AFTER BETTER LOOK AT LATEST MODELS/PRECIP EVOLUTION.
UPDATED GRIDS/PFM/ZFP HAVE BEEN SENT.
&&
.AVIATION...
CONDITIONS WL GRADUALLY ERODE FM VFR ACROSS KSUX THIS AFTERNOON. IT
IS ANTICIPATED THAT KSUX WL STAY VFR THRU THE MORNING HRS...WITH
ALTOCUMULUS CLOUDS IN THE 6K TO 10K FEET AGL LYR. BUT THEN AS THE
LOWER ATMOSPHERE SATURATES...SNOW WL LIKELY BEGIN TO FALL AT KSUX AS
THE AFTERNOON PROGRESSES...DROPPING CIGS DOWN INTO THE MVFR CAT WITH
SOME IFR VIS. DRIER LOW LEVELS PREVAIL AT KFSD AND KHON THRU THE
DAY...AND THESE TWO SITES SHOULD STAY VFR THRU 00Z THIS EVENING...
WITH WORSENING CONDITIONS AFTER THAT.
&&
.PREV DISCUSSION...
STILL ON TRACK FOR A LONG DURATION SNOW EVENT ACROSS A GOOD PORTION
OF OUR CWA THROUGH MONDAY EVENING. CURRENT RADAR SHOWING ECHOES OVER
WESTERN SOUTH DAKOTA INTO NORTHERN AND EASTERN NEBRASKA...THOUGH
LITTLE IS REACHING THE GROUND WITH LOW LEVEL DRY AIR IN PLACE OVER
THE REGION. THE MOST SIGNIFICANT CHANGE FROM PREVIOUS FORECAST IS
THAT MODELS ARE NOW TRENDING FARTHER TO THE NORTH WITH FORCING AND
MOISTURE WITH THE SYSTEM.  WHAT THIS MEANS FOR US IS THAT MORE OF
OUR CWA WILL BE AFFECTED THAN PREVIOUSLY THOUGHT. NICE OVERRUNNING
SITUATION EXPECTED TO DEVELOP OVER THE REGION LATER THIS MORNING AS
LOW TO MID LEVEL WINDS BEGIN TO ADVECT MOISTURE FROM THE
SOUTH...OVER THE VERY COLD AIR SITUATED OVER THE NORTHERN PLAINS.
STRONG ISENTROPIC LIFT WILL INCREASE OVER THE SOUTHERN PORTIONS OF
THE CWA THROUGHOUT THE DAY...WHILE 750 MB FRONTOGENESIS WILL DEVELOP
OVER OUR SOUTHWEST IN THE MORNING...THEN SLOWLY PIVOT ACROSS OUR
SOUTH DURING THE AFTERNOON. WILL SEE LITTLE IN THE WAY OF
PRECIPITATION OVER THE NORTHEASTERN HALF OF THE FA TODAY...WITH THE
DRY LOW LEVEL AIR HOLDING STRONG.
BULK OF THE PRECIPITATION WILL OCCUR TONIGHT INTO TOMORROW MORNING
AS MID LEVEL FRONTOGENESIS/ISENTROPIC LIFT INCREASES...ESPECIALLY
OVER OUR SOUTH AND SOUTHEASTERN QUADRANT OF THE CWA. WITH MID LEVEL
TEMPERATURES HOVERING BETWEEN -15 TO -20 C OVER THE REGION...SNOW
WILL BE VERY EFFICIENT...AND WILL LIKELY SEE IN EXCESS OF A 20 TO 1
LIQUID/SNOW RATIO. PRECIPITATION WILL END FROM NORTHWEST TO
SOUTHEAST ON MONDAY AFTERNOON AS MID AND LOW LEVEL WINDS TURN FROM
THE NORTHWEST...USHERING IN MUCH DRIER AIR POSITIONED JUST TO THE
NORTH OF US. WILL HAVE LITTLE DIURNAL RANGE WITH RESPECT TO
TEMPERATURES FOR TONIGHT INTO TOMORROW WITH CLOUD COVER AND
PRECIPITATION.
IN TERMS OF HEADLINES...KEPT PREVIOUS SNOW ADVISORIES GOING...THOUGH
ADDED ADDITIONAL ADVISORIES NORTHWARD TO THE I 90 CORRIDOR. TOTAL
SNOWFALL AMOUNTS LOOK TO RANGE FROM 2 TO 3 INCHES ALONG THE I 90
CORRIDOR...TO 6 TO 8 INCHES OVER THE SOUTHERN PORTIONS OF OUR
NORTHWESTERN IOWA AND NEBRASKA ZONES. ELECTED TO KEEP A SNOW
ADVISORY...VERSUS A HEAVY SNOW WARNING...IN THESE SOUTHERN AREAS
BECAUSE OF THE LONG DURATION OF THE EVENT.
FOR THE REMAINDER OF THE SHORT TERM...DRYING OUT ON TUESDAY...THEN
ANOTHER SHOT OF REINFORCING COLD AIR ON WEDNESDAY WITH PASSAGE OF A
SHORTWAVE. COULD SEE A LITTLE LIGHT SNOW WITH THIS FEATURE...THOUGH
KEPT LOW POPS AT THIS TIME.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
IA...SNOW ADVISORY FROM NOON TODAY TO 6 PM CST MONDAY FOR IAZ020>022-
     031-032.
     SNOW ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST MONDAY FOR
     IAZ001>003-012>014.
MN...NONE.
NE...SNOW ADVISORY FROM NOON TODAY TO 6 PM CST MONDAY FOR NEZ013-014.
SD...SNOW ADVISORY FROM NOON TODAY TO 6 PM CST MONDAY FOR SDZ070-071.
     SNOW ADVISORY FROM NOON TODAY TO 12 PM CST MONDAY FOR
SDZ050-063-     068-069.
     SNOW ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST MONDAY FOR
     SDZ067.
     SNOW ADVISORY FROM 6 PM THIS EVENING TO 12 PM CST MONDAY FOR
     SDZ064>066.
&&
$$
 JH
</pre> sd
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
935 AM EST SAT JAN 19 2008
.DISCUSSION...14Z SURFACE ANALYSIS WOULD SUPPORT THE ARCTIC COLD
FRONT FROM A TUP (TUPELO MS) TO BNA (NASHVILLE) TO NEAR LEX
(LEXINGTON KY) LINE. HOWEVER...WHAT WILL HURT OUR PRECIPITATION
(PCPN) CHANCES IS THE FACT THAT DEW POINT TEMPS ARE QUITE LOW ON
EITHER SIDE OF THE ARCTIC FRONT THIS MORNING (TEENS TO 20S).
MAIN AREA OF PCPN CONTINUES TO BE TO OUR SE THIS MORNING WITH
HEAVIER PCPN INDICATED FROM CENTRAL GA TO SC...WHERE MOISTURE AND
BEST LIFT (MAINLY ISENTROPIC) IS OCCURRING. WESTERN EDGE OF THE PCPN
SHIELD COULD CLIP THE ERN MTN AREAS WHERE SNOW ADVISORIES RUN TIL
4PM EST...AS ADVERTISED BY LATEST RUC AND GFS MODELS. WEAK FORCING
IS INDICATED INTO THE AFTERNOON HOURS...ALTHO AIRMASS OUTSIDE OF THE
ERN MTNS WILL BE DIFFICULT TO SATURATE GIVEN CURRENT MID TO HIGH
CLOUD DECK AND SUCH LOW DEW POINT TEMPS. SURFACE TEMPS WILL ALSO
HINDER ANY SNOW ACCUMULATIONS.
THUS...WILL LET SNOW ADVISORIES CONTINUE BUT WILL LOWER AMOUNTS FOR
NRN MTNS OF E TN...WITH NO THREAT OF ANY SNOW ACCUMULATIONS WEST OF
THE MTNS. BEST CHANCES OF SNOW STILL APPEAR TO BE OVER CHEROKEE AND
CLAY COUNTIES...BUT SURFACE TEMPS THERE MAY BE TOO WARM FOR SNOW TO
ACCUMULATE.
&&
.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN             39  18  38  17  48 /  50  20   0   0  10
KNOXVILLE MCGHEE TYSON AIRPORT, TN  38  14  32  14  38 /  50  20   0   0  10
OAK RIDGE, TN                       38  14  31  13  43 /  50  20   0   0  10
TRI CITIES AIRPORT, TN              36  12  27   7  40 /  50  20   0   0  10
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...SNOW ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR THE FOLLOWING
     ZONES: CHEROKEE...CLAY.
TN...SNOW ADVISORY FROM 6 AM THIS MORNING TO 4 PM EST THIS AFTERNOON
     FOR THE FOLLOWING ZONES: JOHNSON...SOUTHEAST CARTER...
     SOUTHEAST GREENE...UNICOI.
     SNOW ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR THE FOLLOWING
     ZONES: BLOUNT SMOKY MOUNTAINS...COCKE SMOKY MOUNTAINS...
     EAST POLK...SEVIER SMOKY MOUNTAINS...SOUTHEAST MONROE.
VA...NONE.
&&
$$
TG
</pre> tn
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
318 AM CST SAT JAN 19 2008
.DISCUSSION...
MIDLEVEL TROUGH/VORT HAVE PRETTY MUCH CLEARED THE AREA...WITH RAIN
ACTIVITY CEASING AND MOVING TO THE NORTHEAST. CLOUD COVER
BEGINNING TO FADE AS WELL..WITH BREAKS NOTED IN LOW OVERCAST IN
LOCAL ASOS OBS. LATEST RUC RUN HAS THE CLOUD COVER OUT OF THE
WESTERN ZONES BY DAWN...WITH CLEARING ALONG THE COAST BY NOON.
ADVANCING DOME OF SFC HIGH PRESSURE BEING PULLED SOUTHWARD THROUGH
TEXAS WILL BRING ANOTHER NIGHT OF COLD TEMPS...WITH LOWS IN THE
LOW 40S CAMERON COUNTY TO NEAR FREEZING IN NORTHERN JIM HOGG AND
BROOKS COUNTIES. THE SFC HIGH MOVES EAST OVER THE WEEKEND...WITH
ONSHORE FLOW REDEVELOPING LATE SUNDAY. THIS WILL BRING BACK THE
CHANCE FOR RAIN DUE TO MORE OVERRUNNING LIKE YESTERDAY. UPPER
LEVEL WINDS DURING MOST OF THE NEXT WEEK WILL CONTINUE TO BE FROM
THE SOUTHWEST. THIS WILL KEEP COLD FRONT FROM ADVANCING INTO THE
GULF. THE NEXT FRONT IS EXPECTED LATER TUESDAY...AND MAY STALL
THROUGH THE CWA OR TRANSITION INTO ANOTHER COASTAL TROUGH DURING
THE MIDDLE OF NEXT WEEK. THIS WILL LEAD TO ANOTHER ROUND OF LIGHT
RAIN SHOWERS...ESPECIALLY NEAR THE FRONTAL ZONE. LACK OF COLD AIR
BEHIND FRONTS WILL ALLOW TEMPS TO RECOVER BACK TO NEAR NORMAL NEXT
WEEK...WITH SOME SLIGHTLY ABOVE NORMAL READINGS POSSIBLE TUESDAY
AND WEDNESDAY.
&&
.AVIATION...
LOW PRESSURE IS EXITING THE REGION WITH DRIER AIR ALOFT ADVANCING
NORTHEAST. MVFR TO OCCASIONAL IFR CIGS ARE EXPECTED THROUGH MID
MORNING THEN THE OVERCAST SKIES SHOULD RAPIDLY BREAK BY MID
MORNING AND CONTINUE TO CLEAR SW TO NE THE REST OF THE DAY. CLEAR
SKIES TONIGHT INTO EARLY SUNDAY WITH SOME POSSIBLE PATCHY GROUND
FOG DEVELOPING. CLOUDS INCREASE ONCE AGAIN SUNDAY WITH CIGS
POSSIBLY LOWERING TO MVFR LATE.
&&
.MARINE...
AT 2 AM BUOY 42020 INDICATED SEAS AT 12.5 FEET WITH AN 8 SECOND
PERIOD AND WINDS FROM THE NORTHWEST AT 30 KNOTS WITH GUSTS AROUND
35 KNOTS. STRONG NORTH TO NORTHWEST WINDS AND HIGH SEAS WILL
PERSIST MUCH OF TODAY AS THE TIGHT PRESSURE GRADIENT BETWEEN A
DEPARTING LOW PRESSURE AREA OVER THE WESTERN GULF AND BUILDING
HIGH PRESSURE OVER NORTH TEXAS IS MAINTAINED. WINDS AND SEAS
SLOWLY RELAX TONIGHT INTO SUNDAY AS THE HIGH PRESSURE RIDGE
BECOMES THE DOMINATE WEATHER FEATURE. SMALL CRAFT ADVISORIES WILL
CONTINUE FOR ALL MARINE AREAS THROUGH THE MORNING WITH FLAGS
LOWERED FOR THE LAGUNA THIS AFTERNOON AS WINDS ARE EXPECTED TO
DROP BELOW 20 KNOTS SUSTAINED. WINDS OFFSHORE MAY LOWER BELOW
SMALL CRAFT CRITERIA HOWEVER SEAS MAY BE SLOW IN SUBSIDING THUS
SMALL CRAFT ADVISORIES ARE EXTENDED INTO SUNDAY MORNING. AN
EASTERLY SWELL SETS UP LATER SUNDAY INTO THE FIRST HALF OF NEXT
WEEK AS WINDS VEER EAST TO SOUTHEAST AS HIGH PRESSURE SETTLES OVER
THE SOUTHEAST U.S. TWO COLD FRONTS MOVE INTO THE NORTHERN
GULF...ONE TUESDAY AND ANOTHER THURSDAY...BUT CONFIDENCE IS LOW ON
HOW FAR SOUTH THEY PUSH BEFORE THEY STALL. OVERALL...MARINE
CONDITIONS COULD REMAIN ROUGH THROUGH MUCH OF THE COMING WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  57  44  67  61 /   0   0  10  20
BROWNSVILLE          57  43  68  60 /   0   0  10  20
HARLINGEN            58  41  66  59 /   0   0  10  20
MCALLEN              59  42  66  57 /   0   0  10  20
RIO GRANDE CITY      58  38  64  56 /   0   0  10  10
SOUTH PADRE ISLAND   57  46  67  62 /   0   0  10  20
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...HIGH SURF ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR TXZ251-256-
     257.
GM...SMALL CRAFT ADVISORY UNTIL NOON CST TODAY FOR GMZ130-132-135.
     SMALL CRAFT ADVISORY UNTIL 6 AM CST SUNDAY FOR GMZ150-155-170-
     175.
&&
$$
THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:
HTTP://WWW.WEATHER.GOV/BROWNSVILLE
64/59
</pre> tx
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
319 PM CST SUN JAN 20 2008
.SHORT TERM...THROUGH WEDNESDAY NIGHT
ENTIRE TIME FOCUSED ON INCOMING SNOW EVENT WHICH WILL HAVE TRAVEL
IMPACTS...PERHAPS SIGNIFICANT IN SOME AREAS. ANCILLARY CONCERNS
WERE EARLY EVENING TEMP PLUNGE TONIGHT...AND WINDS/COLD ON TUES
AND WEDNESDAY.
CURRENTLY...ARCTIC AIRMASS REMAINS ENTRENCHED WITH AXIS OF 1035+MB
HIGH PRESSURE FROM ERN ND ALL THE WAY INTO DEEP SOUTH.
TEMPERATURES TODAY ABOUT 5F WARMER THAN YDAY. THICK VEIL OF
MID/HIGH LEVEL CLOUDS ALREADY ESTABLISHED ON BACKSIDE OF POOL OF
ARCTIC AIR WHERE STRONG LOW/MID LEVEL BAROCLINIC ZONE IN PLACE.
INTENSE UPPER LOW /PER GOES WATER VAPOR/ DIGGING DOWN WEST COAST
OF WA/OR AND HEIGHTS PER 20.18Z RUC HAVE REALLY RISEN LAST 12HRS
OVER THE CNTL CONUS IN DOWNSTREAM RIDGING FROM THIS FEATURE.
BACKSIDE OF THE SFC/LOW LEVEL RIDGE AXIS FEATURES A SLY LOW LEVEL
JET OVER 45KTS ALREADY IN SRN PLAINS...FURTHER TIGHTENING THE MID
LEVEL BAROCLINIC ZONE AS THE FLOW BACKS IN RESPONSE TO WRN
CONUS/CNTL CANADA POSITIVE TILT TROUGH AXIS. WATER VAPOR SHOWING
ENERGY OVER WY/ID SHEARING OUT OF THE WRN TROUGH...AND MSAS SHOWS
WEAK LEE CYCLOGENESIS IN ERN COLORADO IN RESPONSE. BROAD/MODEST
UPPER TROPOSPHERIC JET IN PLACE OVER LOCAL AREA /110KT/ BETWEEN
DEPARTING PORTION OF POLAR VORTEX AND RISING CNTL CONUS HEIGHTS.
RADAR MOSAICS OVER NEB/SD SHOW BAND OF MODERATE SNOW /VSBYS LESS
THAN 1SM/ ALREADY ESTABLISHED FROM WRN SD INTO ERN NEB...AND
LIGHTER INTO MUCH OF WRN IA...WHERE DEFORMATION/CONVERGENCE
ALREADY STRONG. THESE FEATURES ALL IN PLAY ON UPCOMING SNOW FORECAST.
SNOW EVENT...HIGH CONFIDENCE IN IMPACTING SNOW EVENT BEGINNING
LATER TONIGHT OVER NERN IA...EXPANDING AND INTENSIFYING MONDAY
OVER MUCH OF FORECAST AREA...DIMINISHING FROM WEST TO EAST MONDAY
EVENING. WITH NRN FRINGE OF SNOW BAND IN OUR FORECAST AREA...THERE
ARE SOME SIGNIFICANT CHALLENGES...NOT TO MENTION GENERAL LATITUDE
OF HEAVIER SNOW ACCUMS. LATEST NAM-WRF RUNS CONTINUE TO BE ON THE
NRN-MOST EDGE OF THE GUIDANCE ENVELOPE...WITH FOCUSING NEAR-
WARNING TYPE SNOW BAND FROM RST/LSE THROUGH MAUSTON/BLACK RIVER
FALLS. THIS VERY EASILY TRACED TO A FURTHER NORTH TRACK OF
ASSOCIATED PV ANOMALY ON 1.5 PV SFC /CURRENT ENERGY IN IDAHO/
ACROSS NRN IA AND SRN WISCONSIN...WITH SFC REFLECTION OF THE WAVE
TO DEVELOP OVER SERN IA MOVING TO MILWAUKEE BY 12Z TUESDAY. REST
OF NON-ENSEMBLE DATASETS ARE A TAD WEAKER...AND FURTHER
SOUTH...WITH SFC LOW DEVELOPMENT THROUGH NRN IL INTO LOWER MICH AS
THE UPPER PV SHIFTS THROUGH SRN IA/NRN MO. THIS HAS BIG
IMPLICATIONS ON THE NRN FRINGE OF THE SNOW BAND...BUT HAS LITTLE
IMPLICATION FOR SAY...NORTHEAST IOWA...WHERE TRACK DOESN/T MATTER
SO MUCH...IT WILL SNOW AND ACCUMULATE THERE REGARDLESS.
FROM A FORCING STANDPOINT...I HAVE NO BEEF BETWEEN THE LATEST
20.12Z NAM-WRF OR GFS. BOTH SHOW ANOMALOUS LOW LEVEL FLOW /SRN
PLAINS 850MB FLOW 3 TO 5 SIGMA ABOVE CLIMO/ WITH STRONG TO VERY
STRONG WARM ADVECTION SIGNAL AND ISENTROPIC ASCENT /275-285K
LAYER/. MOISTURE REALLY STARTS TO WORK INTO THE SYSTEM DURING DAY
ON MONDAY WITH SPEC HUMIDITIES OF 3-4 G/KG INTO NRN MO/SRN IA ON
280K SFC...AS 850MB MOISTURE FLUX IS A WELL-AGREED UPON 4 SIGMA
ABOVE CLIMO BETWEEN WRF/GFS FROM THE GULF COAST INTO MO. NOT QUITE
ALL THE WAY UP HERE...BUT MOISTURE WILL CERTAINLY BE INCREASING
AND BROUGHT TO SATURATION ISENTROPICALLY AS THE SYSTEM ORGANIZES
MORE ON MON. BOTH MODELS ALSO WELL AGREED IN 135KT UPPER JETLET
OVER GREAT LAKES MOVING ONLY VERY SLOWLY EAST KEEPING BROAD SCALE
SUPPORT FOR ASCENT OVER THE MN/WI/IA AREA. AS EXPECTED...SLOPED
FRONTOGENETICAL AXIS IN PLACE AND RELATIVELY SLOW MOVING FROM LATE
TONIGHT INTO MONDAY EVENING OVER FORECAST AREA. PATTERN NOT OVERLY
AMPLIFIED...SO ALL FORCING SIGNALS A TAD MUTED...BUT NOT TO TAKEN
LIGHTLY...ESPECIALLY GIVEN A CONSISTENT TREND IN THE BUFR
SOUNDINGS /GFS AND WRF ALL SITES SOUTH OF I-90/ HAVING DEEP
ISOTHERMAL LAYER FROM THE SFC-650MB THROUGH THE DURATION OF THE
SNOW EVENT. IT/S IMPORTANT TO NOTE THAT THE LIFT SOMETIMES RESIDES
ABOVE THIS REGION AT DIFFERENT LOCATIONS/TIMES...SO GREAT
DENDRITIC GROWTH WILL NOT ALWAYS BE ATTAINED...HOWEVER...CERTAIN
AREAS ARE APT TO SEE PROLONGED EFFICIENT SNOW PRODUCTION. THIS IS
WHERE THE CRUX OF THE SNOW AMOUNT FORECAST BECOMES DIFFICULT.
FROM A GFS/ECMWF STANDPOINT...FORCING SIGNALS A STEP WEAKER THAN
NAM/SREF...AND HENCE TOTAL QPF FROM LATE TONIGHT INTO TUES NIGHT
ABOUT 0.10 TO 0.15 LIGHTER THAN NAM/SREF MEAN. ORDINARILY NOT A
BIG DEAL...BUT WITH EXPECTED RATIOS FROM 18/1 TO 25/1 /COBB
ANALYSIS/...THAT QUICKLY BRINGS A 2-3 INCH DIFFERENCE AT ANY GIVEN
POINT...AND WHILE NAM CONTINUES TO DRIFT NORTH...ALL OTHER MODELS
HAVE TOO...AND THINK SREF MEAN /WHICH ALSO HAS DRIFTED NORTH WITH
TIME/ PROBABLY CAPTURES THE AXIS MOST DEFINITIVELY...AND
INCORPORATED THIS INTO FORECAST.
AMOUNTS...EXPECT WIDESPREAD 3 TO 4 INCH AMOUNTS ALONG AND SOUTH OF
INTERSTATE 90...GIVEN 20/1 RATIOS AVERAGED OVER THE STORM. CONCERN
LIES WITH AN OVERALL FAVORABLE SETUP FOR LONG DURATION MOD SNOW
WITH FAVORABLE DENDRITIC SOUNDINGS...MAKING NAM/WRF AND SREF MEAN
TOTAL QPFS FROM 0.30 TO 0.40 VERY ACHIEVABLE. THIS WOULD SUGGEST
A LONG DURATION EVENT OVER 6 INCHES...WITH SOME 7 TO 8 INCH
AMOUNTS NOT OUT OF THE QUESTION ON WHATEVER LATITUDE /MOST LIKELY
RST TO LSE TO MAUSTON/ THE HEAVIER BANDS/RATIOS BECOME
ESTABLISHED. THERE MAY VERY WELL NEED TO BE A SHORT TERM UPGRADE
TO WARNING GIVEN UNCERTAINTIES HERE...AND NEED TO RAISE AWARENESS
THAT SNOW LIKELY TO FALL QUITE HEAVILY FROM TIME TO TIME ON MONDAY
MORNING INTO THE AFTERNOON OVER THE FORECAST AREA. NAM-WRF HAS
BEEN SCARY-CONSISTENT IN THIS TYPE OF SETUP...GFS AND ECMWF NOT
NEARLY AS MUCH...AND PROBABLY OF MOST CONCERN...IS SREF MEAN QPF
THAT CONTINUES TO INCREASE TOWARD OPNL NAM-WRF VALUES AND SHIFT NORTH
MAKING THIS STORM DEAD-CENTER ON THE LA CROSSE FORECAST AREA.
ISSUED HIGH-END SNOW ADVISORY FOR AREAS ALONG/SOUTH OF I-90...WITH
CONCERN ANOTHER TIER OF COUNTIES TO THE NORTH MAY NEED TO BE ADDED.
WINDS WILL COME UP AS STORM ENDS FOR TUESDAY...AND TEMPERATURES
MOVE LITTLE. ANOTHER ARCTIC FRONT AND TEMP PLUNGE ON WED...WHICH
WILL LIKELY FEATURE FALLING TEMPS AND PERHAPS BLOWING SNOW.
.LONG TERM...THURSDAY THROUGH SUNDAY
EXTENDED PORTION OF THE FORECAST WILL START ON A BITTERLY COLD
NOTE ON THURSDAY MORNING IN WAKE OF MOST RECENT ARCTIC FRONTAL
SURGE. WITH CONSISTENT GFS 925MB TEMPERATURES ONLY A FEW DEGREES
WARMER THAN THIS PAST WEEKENDS NUMBERS...EXPECT WIDESPREAD SINGLE
DIGITS AND TEENS BELOW ZERO...WITH COLD SPOTS IN CNTL WISCONSIN
WELL INTO THE 20S BELOW ZERO. ONLY CAVEAT WILL BE A LITTLE WIND AS
BIG 1037MB SFC HIGH SETTLES THROUGH WRN IA/ERN NEB. BUT WINDS HAVE
CONSISTENTLY DECOUPLED IN MOST AREAS THE PAST FEW NIGHTS...SO
EXPECT A FRIGID NIGHT. AS THE LARGE CNTL CONUS HIGH SETTLES
SOUTH/EAST INTO THE SERN CONUS...STRONG WARM ADVECTION REGIME WILL
QUICKLY DO ITS BEST TO SCOUR OUT REMNANT ARCTIC AIR. SHOULD SEE
TEMPERATURES WARM QUICKLY AS HEIGHTS RISE DOWNSTREAM OF DEEP WRN
CONUS TROUGHING...WHICH IS A MANIFESTATION OF SLOW PATTERN
RETROGRESSION INTO A MEAN WRN TROUGH THROUGH THE EXTENDED. WILL
SEE SEVERAL PIECES OF ENERGY EJECT OUT OF WRN TROUGH INTO CNTL
CONUS THROUGH THE END OF WEEK INTO NEXT WEEKEND...WITH FRI/SAT
WAVE SHOWING PROMISE FOR ACCUMULATING SNOW. MODELS VERY HIT/MISS
ON AMPLITUDE/SPEED OF THIS WAVE...BUT DEGREE OF MOISTURE/WARM
ADVECTION SUGGESTS MOISTURE WILL BE AMPLE TO TAP. MAINTAINED SNOW
CHANCES FRI/FRI NIGHT IN ADVANCE OF THIS WAVE. MODERATING
TEMPERATURES WILL LIKELY FINALLY GET US BACK TO NORMAL BY WEEKEND.
&&
.AVIATION...
CLEAR/GOOD VFR CONDITIONS AT THE TAF SITES EARLY IN THE PERIOD WILL
DETERIORATE TO IFR BY MID MONDAY MORNING. INCREASING FORCING/LIFT/
MOISTURE FROM THE SOUTHWEST WILL SPREAD THICKENING/LOWERING CLOUDS
ACROSS THE TAF SITES FROM LATE THIS AFTERNOON THRU ABOUT 09Z
TONIGHT. AS LIFT/MOISTURE CONTINUE TO INCREASE AND LOWER LEVEL
SATURATION OCCURS...LIGHT SNOW THEN MDT SNOW EXPECTED TO SPREAD FROM
SOUTHWEST TO NORTHEAST ACROSS THE AREA BETWEEN 09Z-15Z...WITH
CIGS/VSBYS LOWERING INTO THE IFR RANGE A COUPLE HOURS AFTER THE -SN
STARTS.  STRONGEST/DEEPEST LIFT TO SPREAD ACROSS THE AREA FROM MID-
DAY MON INTO MON EVENING WITH IFR CONDITIONS/MDT SNOW THRU THE REST
OF MON INTO MON NIGHT. SEVERAL INCHES OF SNOW POSSIBLE AT BOTH
KRST/KLSE MON THRU MON NIGHT...FOR RUNWAY CLEARING/SNOW OPS ISSUES.
BRISK WINDS ON TUE MAY CREATE SOME DRIFTING OF THE NEW FLUFFY
SNOW...ESPECIALLY AT KRST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...SNOW ADVISORY FROM 6 AM MONDAY TO MIDNIGHT CST MONDAY NIGHT FOR
     WIZ041-WIZ042-WIZ043-WIZ044-WIZ053-WIZ054-WIZ055-WIZ061.
MN...SNOW ADVISORY FROM 6 AM MONDAY TO MIDNIGHT CST MONDAY NIGHT FOR
     MNZ086-MNZ087-MNZ088-MNZ094-MNZ095-MNZ096.
IA...SNOW ADVISORY FROM MIDNIGHT TONIGHT TO MIDNIGHT CST MONDAY NIGHT
     FOR IAZ008-IAZ009-IAZ010-IAZ011-IAZ018-IAZ019-IAZ029-IAZ030.
&&
$$
SHORT/LONG TERM...BINAU
AVIATION...RRS
</pre> wi
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
415 AM EST SUN JAN 20 2008
.SYNOPSIS...
08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS CONTINUES TO SHOW
AN AMPLIFIED PATTERN ACROSS NORTH AMERICA...WITH STRONG RIDGING FROM
THE EAST PACIFIC INTO NW CANADA...TROUGHING OVER THE PACIFIC NW...
AND A BROAD UPPER TROUGH OVER THE EAST HALF OF CANADA. NW UPPER FLOW
WHICH HAS BEEN OVER UPPER MI THE PAST FEW DAYS IS TURNING MORE
WESTERLY...DUE TO THE COMBINATION OF THE DIGGING PACIFIC NW TROUGH
AND A SHRTWV DROPPING SOUTH INTO SOUTHERN SASKATCHEWAN. THIS
WESTERLY FLOW IS GRADUALLY BRINGING WARMER AIR INTO UPPER MI AS
NOTED BY 850MB TEMP RISES OF 4C AT MPX AND INL BETWEEN 12Z AND 00Z.
HOWEVER...THE AIRMASS STILL REMAINS COLD...GIVEN THE -24C READING AT
INL AND -19C AT MPX. THUS...LAKE EFFECT CONTINUES OFF LAKE SUPERIOR.
HOWEVER...THE BANDS ARE BECOMING MORE EAST-WEST ORIENTED THANKS TO
THE UPPER LEVEL HEIGHT RISES SUPPORTING MORE WESTERLY LOW LEVEL
FLOW...IN ADDITION TO LAND BREEZES WHICH HAVE DEVELOPED. TEMPS
INLAND HAVE DROPPED INTO THE TEENS BELOW ZERO...BUT HAVE NOT DROPPED
MUCH MORE DUE TO INCREASING HIGH CLOUDS IN THE UPPER FLOW. TO THE
WEST...A FAIRLY POTENT SHRTWV CAN BE SEEN CROSSING NEVADA.
DOWNSLOPING WESTERLY FLOW AHEAD OF THIS SHRTWV HAS CAUSED PRESSURE
FALLS IN THE TEXAS PANHANDLE. FROM THE DEVELOPING LOW PRESSURE...A
WARM FRONT EXTENDS NE INTO SW IOWA.
&&
.DISCUSSION...
MAIN FORECAST CONCERN IS SNOWFALL OVER THE KEWEENAW THROUGH TONIGHT.
TODAY...SHRTWV OVER NEVADA WILL HEAD OUT INTO THE CENTRAL PLAINS...
CAUSING THE TEXAS PANHANDLE LOW TO LIFT UP TOWARDS KANSAS CITY.
MEANWHILE TO OUR NW...THE SHRTWV TROUGH OVER SOUTHERN SASKATCHEWAN
IS PROGGED TO DROP DOWN INTO NORTH DAKOTA AND NW MN. THE COMBINATION
OF BOTH FEATURES WILL RESULT IN THE UPPER FLOW TURNING SW...MORE
FAVORABLE FOR BRINGING WARMER AIR INTO THE CWA. IN FACT...MODELS
BRING 850MB TEMPS UP ABOUT 4C FROM CURRENT READINGS. THIS MAY NOT
SEEM LIKE A WHOLE LOT...BUT IT SHOULD PRODUCE A MORE FAVORABLE
ENVIRONMENT FOR DENDRITES COMPARED TO THE RECENT SMALLER SNOWFLAKES.
THIS WILL PLAY A ROLE IN TWO DIFFERENT AREAS OF CONCERN. THE FIRST
CONCERN IS THE POSSIBILITY OF SYNOPTIC PCPN WITH THE LOW LIFTING UP
TOWARDS KANSAS CITY. MODELS DEPICT MID-LEVEL FRONTOGENESIS
INCREASING OVER CENTRAL WI INTO NORTHERN LOWER MI DURING THE AFTN.
GIVEN THE LOCATION OF THIS AXIS...AND THE PRESENCE OF A 120-130 JET
STRETCHING FROM UPPER MI EASTWARD...FAVORING UPPER DIVERGENCE SOUTH
OF THE CWA...THINK MUCH OF THE PCPN SHOULD STAY TO THE SOUTH. DRY
AIR PRESENT OVER THE CWA AS INDICATED BY THE 00Z INL AND GRB
SOUNDINGS SHOULD ALSO HOLD SYNOPTIC PCPN FROM MARCHING NORTH. WILL
MAINTAIN CHANCE POPS...BUT RESTRICT THEM JUST TO THE SOUTH CENTRAL.
THE OTHER PCPN CONCERN IS LAKE EFFECT SNOW. FOR THE EASTERN
CWA...SOME LAKE EFFECT MIGHT LINGER FOR A FEW MORE HOURS PAST THE
END TIME OF THE ADVISORY...BUT SEE NO NEED TO EXTEND THE ADVISORY AT
THE PRESENT TIME. OVER THE KEWEENAW...LOW LEVEL WINDS ARE PROGGED TO
BACK A LITTLE MORE SW THAN PREVIOUSLY THOUGHT...WHICH COULD MOVE THE
CURRENT LAKE EFFECT COMPLETELY OFFSHORE FOR SOME OF THE KEWEENAW
THIS AFTERNOON. THIS IS INDICATED BY THE NAM/GFS/LOCAL WRF-ARW RUN.
HOWEVER...THE LOCAL WRF-ARW RUN DOES MANAGE TO BRING A CONVERGENT
BAND BACK INTO THE KEWEENAW AFTER 20Z. FEEL THIS SOLUTION MIGHT BE
THE BEST TO FOLLOW AS IT USUALLY HAS A BETTER HANDLE ON THE LAKE
AGGREGATE. SOUNDINGS DEPICT AT LEAST SOME DENDRITIC GROWTH BETWEEN
THE CLOUD BASE AND 850MB...WHICH MEANS WHEN THE CONVERGENT BAND
MOVES IN...THERE COULD BE SOME DECENT SNOWFALL RATES.
THEREFORE...HAVE LEFT THE GOING ADVISORY INTACT. GIVEN WARMER AIR
MOVING IN...WARMER TEMPS ARE EXPECTED TODAY. ONLY MADE MINOR
ADJUSTMENTS TO HIGHS.
TONIGHT...SHRTWV TROUGH OVER NORTH DAKOTA IS PROGGED TO SHIFT EAST
TOWARDS WESTERN LAKE SUPERIOR BY 12Z TUE. THIS TROUGH SHOULD HELP
PROMOTE A RAPID PROGRESSION OF THE SHRTWV LIFTING UP FROM THE
CENTRAL PLAINS...AND FAVOR THE GFS/UKMET IDEA OF BRINGING THE SHRTWV
INTO LOWER MI BY 12Z WITH A WEAKER SFC LOW SITUATED NEAR ALPENA AT
THE SAME TIME. THIS IS ALSO FAVORED BY HPC. MID-LEVEL FRONTOGENESIS
AND UPPER DIVERGENCE FIELDS FROM THE GFS STILL SUGGEST THE BEST
FORCING FOR PCPN TO REMAIN TO THE SOUTH...THOUGH ENOUGH CONFIDENCE
EXISTS TO RAISE POPS TO LIKELY IN SOUTHERN MNM COUNTY. THE REST OF
THE CWA WILL HAVE LOW CHANCE POPS...AND BOTH AREAS ARE FOR MAINLY IN
THE EVENING AS THE MAIN MID-LEVEL FRONTOGENESIS AREA SHIFTS EAST
AFTER 06Z. NEXT CONCERN IS WITH THE SHRTWV TROUGH...AS 850MB TEMPS
FALL 1-2C. LOW LEVEL FLOW TURNS MORE WESTERLY IN THE EVENING...SO
THE LAKE EFFECT BAND ENTERING THE KEWEENAW THIS AFTERNOON SHOULD
REMAIN FAIRLY PROGRESSIVE...STALLING OUT AND WEAKENING OVER
ONTONAGON COUNTY LATER IN THE NIGHT. HAVE EXTENDED THE ADVISORY FOR
THE KEWEENAW TO 06Z TONIGHT TO ACCOUNT FOR THE LAKE EFFECT BAND. TO
THE EAST...THE SWITCH TO MORE WEST TO EVEN NW WILL BRING THE EASTERN
EXTENT OF THE BAND DOWN INTO LUCE/ALGER COUNTIES...FOLLOWED BY THE
TYPICAL ONTARIO LAND BREEZE CONVERGENT BAND FROM NE LAKE SUPERIOR
INTO LUCE COUNTY. THE REST OF THE CWA SHOULD SEE SOME CLEARING
DURING THE OVERNIGHT HOURS TO ALLOW TEMPS TO FALL. WILL TREND TEMPS
DOWNWARD GIVEN THIS CLEARING POSSIBILITY AND A DRY AIRMASS IN PLACE.
TUE...SHRTWV TROUGH SWINGS INTO UPPER MI. WITH THIS TROUGH COMES
ANOTHER COOL BLAST OF AIR...WITH 850MB TEMPS OF -24 TO -26C ENTERING
WESTERN LAKE SUPERIOR BY 00Z WED. THUS...MORE LAKE EFFECT IS
EXPECTED. SURFACE PATTERN SHOWS LAKE INDUCED TROUGHING SETTING
UP...WITH LOW PRESSURE NEAR WHITEFISH POINT AND A TROUGH EXTENDING
WEST THROUGH TWIN LAKES. THE HEAVIEST LAKE EFFECT SNOW...WHICH WILL
NOT BE ALL THAT HEAVY GIVEN THE COLD AIR MOVING IN REDUCING SNOW TO
WATER RATIOS...WILL BE CONFINED TO THE TROUGH AS IT PROVIDES A
SOURCE OF CONVERGENCE. THUS...AGAIN THE WESTERN U.P. AND THE AREA
FROM ALGER INTO NORTHERN LUCE COUNTY IS EXPECTED TO BE UNDER THE GUN
FOR SNOW. DRY WEATHER IS EXPECTED FOR THE REST OF THE CWA...WITH
TEMPS FAIRLY SIMILAR TO THOSE ON MON. TEMPS COULD FALL LATE IN THE
DAY AS THE COLDER AIR MOVES IN.
TUE NIGHT INTO WED...SHRTWV TROUGH HEADS OFF TOWARDS QUEBEC TUE
NIGHT WHILE ANOTHER SHRTWV TROUGH DROPS SOUTH THROUGH SOUTH CENTRAL
CANADA. THIS SECOND SHRTWV TROUGH...WITH A LITTLE MORE OF A COLD AIR
PUNCH...SHOULD ENTER UPPER MI DURING THE DAY WED. THUS...CONTINUED
LAKE EFFECT WITH CONTINUED BELOW NORMAL TEMPERATURES ARE EXPECTED.
WIND FLOW DOES TURN A BIT MORE NORTHERLY WITH THE SECOND SHRTWV
TROUGH WEDNESDAY MORNING...WHICH MEANS MARQUETTE AND WESTERN ALGER
COUNTIES MAY PICK UP SOME SNOW. HOWEVER...THE MORE NORTHERLY WINDS
DO NOT LAST LONG...AS MODELS SHOW ANY LAKE EFFECT BANDS HEADING OFF
TOWARDS EASTERN ALGER COUNTY LATER WED AFTERNOON. EITHER WAY...IT
STILL LOOKS LIKELY THAT ALL OF THE WESTERN COUNTIES WILL PICK UP
MORE SNOW...THOUGH AGAIN WITH THE COLD 850MB TEMPS (DROPPING TO
AROUND -26C BY 18Z WED) SUGGESTS FINER SNOWFLAKES. ONLY MINOR TWEAKS
WERE MADE TO THE GOING LOW AND HIGH TEMPS.
WED NIGHT INTO THU...THE PATTERN STARTS TO CHANGE DURING THIS
PERIOD...AS THE SHRTWV TROUGH OVER THE CWA DIGS DOWN TOWARDS THE
OHIO VALLEY AND THE CURRENT EAST PACIFIC RIDGE GETS PUSHED EASTWARD
TOWARDS THE CWA. HOWEVER...850MB TEMPS EVEN AT 18Z THU ARE STILL
DEPICTED BELOW -18C. NOT UNTIL 00Z DO 850MB TEMPS START TO GET WARM
ENOUGH OVER WESTERN LAKE SUPERIOR TO ALLOW LAKE EFFECT TO END (-8 TO
-10C) THUS...WITH WNW WINDS THROUGH THIS PERIOD...MORE LAKE EFFECT
SNOW IS EXPECTED FOR THE WESTERN U.P. AND ALGER INTO NORTHERN LUCE
COUNTIES. TEMPS COULD GET QUITE CHILLY WED NIGHT IF SKIES CAN
CLEAR...AS NOTED BY MEX COOP GUIDANCE OF -20F AT CHAMPION. ALTHOUGH
WE ARE WARM ADVECTING ON THU...TEMPS WILL STRUGGLE TO GET MUCH
HIGHER THAN THE LOW TEENS...IF EVEN 10 ABOVE IN INLAND LOCATIONS.
BEYOND THU...THE EAST PACIFIC RIDGE BUILDS INTO THE CWA FOR
FRI...CAUSING 850MB TEMPS TO CLIMB TO PERHAPS AS HIGH AS -4C. MEX
GUIDANCE RESPONDS ACCORDINGLY BY SHOWING HIGH TEMPS IN THE MID 20S.
GIVEN THE GOOD AGREEMENT WITH THE 00Z ECMWF...HAVE RAISED HIGHS A
FEW DEGREES. NO OTHER CHANGES MADE BEYOND FRIDAY.
&&
.AVIATION (FOR THE 06Z TAF ISSUANCE)...
LES/GENERALLY IFR/LIFR VSBYS AND MVFR/OCNL IFR CIGS WL CONTINUE AT
CMX INTO MON MRNG BEFORE BACKING LLVL FLOW AND ADVECTION OF STABLE/
DRY ARCTIC AIR CONSPIRE TO AT LEAST DIMINISH THE LES AND RESULT IN
IMPROVING CONDITIONS ON MON. LATEST MODEL GUIDANCE HAS TRENDED
FARTHER N WITH PLACEMENT OF LK INDUCED TROF N OF CMX. PER NAM MODEL
FCST SDNGS...FCST IMPROVED VSBY TO VFR UNDER AN MFVR CIG TO ACCOUNT
FOR THIS DVLPMNT. ALSO TRENDED BACK FCST ARRIVAL TIME OF THE TROF/
ONSET OF IFR CONDITIONS UNTIL LATE MON EVNG THAT IS STILL EXPECTED
WITH VEERING FLOW IN THE WAKE OF DISTURBANCE PASSING TO THE S THRU
THE CNTRL GRT LKS. SINCE SAW WL BE ON THE S SIDE OF THE LK INDUCED
TROF AND UNDER THE DOMINATION OF DRY...CONTINENTAL ARCTIC
AIR...EXPECT VFR CONDITIONS THERE THRU THE PD. BUT THERE WL BE AN
INCRS IN HI/MID CLDS STARTING LATE TNGT COINCIDENT WITH THE PASSAGE
OF THE DISTURBANCE TO THE S.
&&
.MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)...
WEST TO NORTHWEST WINDS IN THE 15 TO 30 KT RANGE WILL GRADUALLY BACK
TO SOUTHWEST OR WEST AS A TIGHT GRADIENT PERSISTS BETWEEN
ARCTIC HIGH PRESSURE BUILDING SOUTHEAST FROM THE PLAINS AND A
LINGERING TROUGH INTO THE UPPER GREAT LAKES. LOW PRESSURE WILL MOVE
FAR ENOUGH SOUTH OF THE AREA SO THAT LAKE INDUCED TROUGHING TONIGHT
INTO TUE WILL KEEP MAINLY W OR WSW WINDS GOING OVER THE SOUTH
PORTION OF THE LAKE AND NW WINDS OVER THE NORTH HALF WITH WIND
VALUES MAINLY IN THE 15 TO 25 KT RANGE. A COLD FRONT WILL MOVE
THROUGH TUESDAY NIGHT WITH WINDS VEERING NORTHERLY BY WED. HEAVY
FREEZING SPRAY WILL CONTINUE THIS MORNING DUE TO THE STRONG WINDS
AND VERY COLD ARCTIC AIR. HEAVY FREEZING SPRAY WILL AGAIN DEVELOP
TUESDAY NIGHT INTO WEDNESDAY AS A REINFORCING BATCH OF ARCTIC AIR
AND STRONGER WINDS MOVES IN.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
MICHIGAN...
  LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 1 AM EST
    TUESDAY FOR MIZ001-003.
  LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST THIS
    MORNING FOR MIZ002.
  LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 5 AM EST EARLY
    THIS MORNING FOR MIZ006-007.
LAKE SUPERIOR...
  HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST THIS AFTERNOON FOR
     LSZ162-263>267.
LAKE MICHIGAN...
  HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST THIS MORNING FOR
     LMZ248-250.
&&
$$
SYNOPSIS/DISCUSSION...AJ
AVIATION...KC
MARINE...JLB
</pre> mi
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PUEBLO CO
504 AM MST MON JAN 21 2008
.UPDATE...
A QUICK UPDATE TO ISSUE A DENSE FOG ADVISORY FOR EL PASO COUNTY.
LIVE WEBCAMS ARE SHOWING FAIRLY POOR VISIBILITIES ACROSS MUCH OF
COLORADO SPRINGS. THIS IS NOT SURPRISING GIVEN THE CLEAR NIGHT
LAST NIGHT AND LCL HEIGHTS ARE PRETTY CLOSE TO THE GROUND. GIVEN
THE LIGHT SOUTH-SOUTHEAST UPSLOPE WIND ACROSS EL PASO COUNTY...I
DON`T SEE ANY REASON WHY THE FOGGY CONDITIONS WOULD IMPROVE THIS
MORNING. A DIFFICULT MORNING COMMUTE WILL BE LIKELY FOR EL PASO
COUNTY THIS MORNING. ALSO...THIS IS DENSE FREEZING FOG...SO FREE-
AIR SURFACES...LIKE BRIDGES/OVERPASSES...COULD BECOME SLICK IF NOT
TREATED. METZE
&&
.PREV DISCUSSION... /ISSUED 432 AM MST MON JAN 21 2008/
SHORT TERM...
(TODAY AND TONIGHT)
..COMPLEX WEATHER PATTERN TODAY/TONIGHT...
CURRENTLY...COLD FRONT WAS FASTER LAST NIGHT...BY ABOUT 6-9 HOURS.
07Z/21 SURFACE ANALYSIS HAD THE COLD FRONT FROM KTAD AND
TRANSITIONING TO A STATIONARY FRONT JUST SOUTH OF KSPD INTO KS.
1030-1040MB HIGH PRESSURE WAS ACROSS THE NORTHERN ROCKY MOUNTAINS
INTO THE NORTHERN PLAINS. ASSOCIATED LIFR-MVFR CEILINGS WERE ACROSS
MUCH OF EASTERN CO WITH TERRAIN PLAYING A BIG PART RIGHT NOW.
STRATUS HAS NOT MADE IT INTO COLORADO SPRINGS YET GIVEN THE
NORTHERLY DOWNSLOPE FLOW OFF THE PALMER DIVIDE...HOWEVER KCOS WIND
HAS TURNED EASTERLY AND "FOG" SATELLITE IMAGERY IS SHOWING STRATUS
SPREADING INTO SOUTHERN EL PASO COUNTY. THE STRATUS HAS WORKED ITS
WAY UP THE LOWER AR RIVER VALLEY AND CONTINUES TO FILL-IN ALONG AND
SOUTH OF HIGHWAY 50. REGIONAL RADARS ARE NEARLY ECHO ENERGY-FREE AT
THE MOMENT. EVERY ONCE IN A WHILE...A METAR REPORTS LIGHT SNOW OR
FLURRIES ACROSS NORTHEAST CO. LIVE WEB CAMS NOT SHOWING MUCH
EITHER...EXCEPT FREEZING FOG(AND SOME FREEZING DRIZZLE) AROUND
MONUMENT. MEANWHILE...WATER VAPOR IMAGERY AND RUC MODEL UPPER AIR
ANALYSES REVEALED A RELATIVELY DEEP "DRY" WEST-SOUTHWEST FLOW ACROSS
MUCH OF SOUTHERN CO AND THE DESERT SOUTHWEST. THE AREA OF LOW
PRESSURE WAS SPINNING WELL WEST OF CO ACROSS OR...AND TRENDING
TOWARDS A WESTWARD MIGRATION. IT IS RATHER BRISK-VERY WINDY ACROSS
THE VERY HIGH TERRAIN PER AWOS SENSORS. PIKES PEAK SENSOR REPORTING
SUSTAINED 49 MPH WITH GUSTS AROUND 70 MPH. TEMPERATURES ARE IN THE
SINGLE DIGITS AND TEENS ACROSS MUCH OF SOUTHEAST CO...AND OF
COURSE...ALAMOSA IS APPROACHING -20F.
TODAY AND TONIGHT...VERY COMPLEX WEATHER PATTERN OVER THE NEXT 12-24
HOURS. THERE WILL BE QUITE THE DICHOTOMY OF SENSIBLE WEATHER. RATHER
VIGOROUS WEST-SOUTHWEST FLOW ALOFT WILL CONTINUE ACROSS THE CENTRAL
ROCKIES. BRISK-VERY WINDY CONDITIONS WILL BE FELT ACROSS THE HIGHER
MOUNTAINOUS TERRAIN AND I WOULDN`T BE SURPRISED TO SEE WIND GUSTS OF
40-65 MPH ACROSS THE MOUNTAIN PEAKS AND EASTERN SLOPES OF MOST OF
OUR MOUNTAINS...ESPECIALLY THE NORTHERN SANGRE DE CRISTO MOUNTAINS
GIVEN THE RELATIVELY STRONG WEST-SOUTHWEST FLOW ORTHOGONAL TO THE
BARRIER. VERY S51OW CP AIR MASS SHOULD REMAIN WEDGED UP AGAINST
OUR EASTERN CO MOUNTAINS AND SOUTHEAST CO PLAINS. WILL TRY FOR A
LITTLE TEMPERATURE RECOVERY ALONG AND EAST OF THE I-25 CORRIDOR...
BUT IT LIKELY WILL NOT BE MUCH. THE SAN LUIS VALLEY CENTER FLOOR
WILL CONTINUE TO BE A TEMPERATURE FORECAST C51ENGE. IF THE
SOUTHWEST WINDS CAN PICK UP...THEN TEMPERATURES COULD SHOOT INTO THE
20S/30S...HOWEVER...IF THE WINDS REMAIN LIGHT...THEN HIGH
TEMPERATURES WILL STRUGGLE TO GET INTO THE TEENS. AS FOR
PRECIPITATION...THE BEST DEEP MOISTURE SHOULD BE AROUND THE SAWATCH
AND MOSQUITO MOUNTAIN RANGES AND THIS IS WHERE THE HIGHEST POPS WILL
BE LOCATED. A COUPLE OF INCHES OF SNOW CAN BE EXPECTED.
PRECIPITATION WILL BE QUITE THE C51ENGE ACROSS OUR EASTERN CO
MOUNTAINS AND ADJACENT PLAINS. THE 700-300MB LAYER IS RELATIVELY
"DRY"...ESPECIALLY ACROSS THE FAR SOUTHEAST CO PLAINS. THIS DOESN`T
PROMOTE ANY "SEEDER-FEEDER" ICE CRYSTAL PRECIPITATION FALLING FROM
ABOVE...SO ANY PRECIPITATION WOULD BE LOW LEVEL DRIVEN AND VERY
LIGHT. GIVEN THE THERMAL STRUCTURE...I WOULD THINK LIGHT SNOW AND
DEFINITELY FLURRIES WOULD BE THE GREATEST THREAT. I WILL TRY TO ADD
SOME PRECIPITATION VALUE TO THE FORECAST BY GOING WITH S--(LIGHT
SNOW AND FLURRIES) FOR ALONG AND EAST OF I-25 CORRIDOR TODAY AND
TONIGHT. THERE COULD BE THE POTENTIAL FOR FREEZING DRIZZLE/FREEZING
FOG GENERALLY WEST OF THE I-25 CORRIDOR TOWARDS THE MOUNTAINS WHERE
THE LCL HEIGHT WILL BE NEAR THE GROUND. LATEST MODEL DATA AND
SOUNDINGS SUGGEST THE COLORADO SPRINGS AREA TO HAVE LIFR-IFR
STATUS/FREEZING FOG TONIGHT WITH SURFACE-PBL FLOW
SOUTH-SOUTHEASTERLY UP THE SOUTHERN PORTION OF THE PALMER DIVIDE.
MINIMUM TEMPERATURES ALONG AND EAST OF THE I-25 CORRIDOR WILL
GREATLY DEPEND ON THE CLOUD COVER. IF THE LIFR-MVFR STRATUS
CLEARS...THEN TEMPERATURES WILL TANK. HOWEVER...IF THE CLOUD COVER
REMAINS...THEN TEMPERATURES WILL DROP SLOWLY AND JUST A LITTLE. METZE
LONG TERM...
(TUESDAY THROUGH SUNDAY)
ZONAL TO UPPER RIDGING PATTERN PROJECTED TO OCCUR OVER CWFA FROM
TUESDAY INTO THURSDAY MORNING ALLOWING FOR GENERALLY DRY
CONDITIONS...EXCEPT FOR PORTIONS OF THE WESTERN AND CENTRAL
MOUNTAINS. TEMPERATURES EXPECTED TO MODERATE SLOWLY EACH DAY FROM
TUESDAY INTO THURSDAY BUT CONTINUE TO REMAIN BELOW LATE JANUARY
SEASONAL AVERAGES.
RELATIVELY MOIST SOUTHWEST FLOW ALOFT IS PROJECTED TO PRIMARILY
IMPACT THE WESTERN MOUNTAINS WITH POPS FROM LATER THURSDAY INTO
SUNDAY...WHILE EASTERN PORTIONS OF THE CWFA SHOULD REMAIN
GENERALLY PRECIPITATION FREE. INCREASING WINDS ARE ALSO
ANTICIPATED TO DEVELOP FROM LATER THURSDAY INTO SUNDAY.
FINALLY...TEMPERATURES RUNNING NEAR CLIMATOLOGICAL AVERAGES SHOULD
BE NOTED FROM FRIDAY INTO SUNDAY.
AVIATION...
PER SHORT TERM DISCUSSION...VFR CONDITIONS WILL CONTINUE AROUND THE
ALS TERMINAL.  FOR THE COS TERMINAL AREA...IFR CEILINGS WILL DEVELOP
BETWEEN 10Z-13Z/21 AND CONTINUE MUCH OF TODAY AND TONIGHT. LIGHT
SNOW OR FLURRIES WITH VISIBILITIES OF 1-4 MILES COULD OCCUR AROUND
THE COS TERMINAL AREA THROUGH 12Z/22 WITH THE POTENTIAL OF 1/4-1/2SM
IN FZFG AND LIFR STRATUS BETWEEN 10Z-16Z/21 AND AGAIN AFTER 02Z/22.
FOR THE PUB TERMINAL AREA...IFR-MVFR CEILINGS WILL OCCUR WITH
FLURRIES POSSIBLE THROUGH 12Z/22. METZE
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL NOON MST TODAY FOR COZ084-085.
&&
$$
17/17
</pre> co
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
828 AM EST MON JAN 21 2008
.SYNOPSIS...
HIGH PRESSURE WILL BUILD IN TODAY AND BRINGING AN END TO THE LAKE
EFFECT SNOWS. THE HIGH WILL DOMINATE TONIGHT. A LOW PRESSURE SYSTEM
WILL MOVE ACROSS THE GREAT LAKES REGION TUESDAY AND THROUGH THE
SAINT LAWRENCE VALLEY TUESDAY NIGHT DRAGGING A COLD FRONT ACROSS THE
REGION. THIS SYSTEM WILL BRING LIGHT SNOW TO THE AREA. ANOTHER SHOT
OF ARCTIC AIR IS ON THE WAY FOR LATE IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
06Z RUN OF THE NAM12...CURRENT HOURLY RUC13 AND BUF-WRF ARE DOING
QUITE WELL WITH PLACEMENT AND INLAND EXTENT OF LAKE EFFECT BAND
OFF LAKE ONTARIO. THE NEXT COUPLE OF HOURS (TO AROUND 16Z)...THIS
BAND OF SNOW SHOULD BEGIN TO LIFT NORTHWARD AS LOW LEVEL FLOW
BACKS AROUND DUE TO THE PERIPHERY OF THE SURFACE HIGH SLIDING BY
TO OUR SOUTH AND INVERSION HEIGHTS LOWERING WITH RISING HEIGHTS.
SINCE WE HAVE NOT MET WARNING CRITERIA AND ADDITIONAL AMOUNTS OF
SNOW ARE EXPECTED TO BE AROUND 3 INCHES OR LESS...DOWNGRADED THE
WARNING TO AN ADVISORY AT THIS TIME. THIS BAND WILL CONTINUE TO
LIFT NORTHWARD AND BY THIS AFTERNOON...ANTICIPATE LAKE EFFECT
CONCERNS WOULD HAVE DIMINISHED. NO OTHER CHANGES NEEDED AT THIS TIME.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
GET A BIT OF A BREAK TONIGHT WITH RIDGE DOMINATING WEATHER. SURFACE
HIGH CENTERED OVER OHIO VALLEY WILL SHIFT EASTWARD AND MORE MOVE OFF
THE MID ATLANTIC COAST TONIGHT.
LOW PRESSURE SYSTEM WILL MOVE OUT THE PLAINS TODAY HEADING TOWARD
THE GREAT REGION. THE LOW WILL MOVE ACROSS THE GREAT LAKES TUESDAY
INTO QUEBEC TUESDAY NIGHT DRAGGING ITS COLD FRONT ACROSS THE LOCAL
AREA. EVEN WITH LOW PASSING TO OUR WEST THE COLD AIRMASS IN PLACE
WILL KEEP A SINGLE P-TYPE...SNOW...WITH LIGHT QPF AMOUNTS.  IN THE
WAKE OF THIS SYSTEM ANOTHER ROUND OF LAKE EFFECT SNOWS EXPECTED.
LONG WAVE TROUGH WILL GET REINFORCED OVER THE REGION WEDNESDAY AS
MORE NORTHERN STREAM ENERGY DIVES OUT OF CENTRAL CANADA. CONDITIONS
WILL BE SEASONABLE WITH THE THREAT OF SNOW SHOWERS.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
ON THURSDAY THE 500 HPA TROF DIGS SOUTH AND BEGINS TO MOVE EAST
OF NEW ENGLAND INTO THE ATLANTIC AS A RIDGE MAKES ITS WAY EAST
FROM THE ROCKIES TO THE MISSISSIPPI VALLEY...AND A STRONG SURFACE
HIGH BUILDS INTO THE OHIO VALLEY. TEMPERATURES WILL DROP
THURSDAY NIGHT AS A STRONG GRADIENT ON THE WEST SIDE OF THE UPPER
TROF DRAWS COLD AIR OUT OF CENTRAL CANADA INTO THE REGION AND WE
MAY BE DEALING WITH WIND CHILL ISSUES AS A RESULT. BY FRIDAY
EVENING THE SURFACE HIGH IS FORECAST TO BE OVER TIDEWATER
VIRGINIA...WITH A LOW LEVEL FLOW OF SOMEWHAT WARMER AND MOISTER
AIR FLOWING INTO THE OHIO VALLEY FROM THE SOUTHERN PLAINS AROUND
THE WEST SIDE OF THE HIGH. MEANWHILE A CLIPPER TYPE LOW RACES
ACROSS SOUTHERN CANADA FROM NORTH OF MONTANA ON FRIDAY TO NORTH
OF LAKE HURON BY SATURDAY EVENING. TEMPERATURES ARE EXPECTED TO
MODERATE OVER THE WEEKEND...WITH HIGHS WARMING INTO THE 25 TO
35 DEGREE RANGE SATURDAY AFTERNOON. THE CLIPPER WILL BRING A
CHANCE OF SNOW TO THE NORTHERN AND WESTERN ZONES STARTING
SATURDAY WITH MORE WIDESPREAD WARMING AND CHANCE OF PRECIP ON
SUNDAY WITH HIGHS MIDDAY SUNDAY 30 TO 40 DEGREES...ABOUT FIVE
DEGREES ABOVE NORMAL...BEFORE THE LOW SWEEPS A FRONT THROUGH
THE REGION LATE SUNDAY. IT WILL BE WARM ENOUGH IN MUCH OF THE
HUDSON VALLEY MIDDAY SUNDAY FOR THE SNOW TO MIX WITH...OR EVEN
CHANGE TO RAIN.
&&
.AVIATION /13Z MONDAY THROUGH FRIDAY/...
A WEAK FRONT LAY ACROSS THE MOHAWK VALLEY EARLY THIS MORNING
WHICH SERVED AS A FOCUS FOR SOME LIGHT SNOW SHOWERS ALONG WITH
SOME MOISTURE WHICH CAME DOWN THE MOHAWK VALLEY FROM LAKE ONTARIO.
FOR THE MOST PART...THE AIR MASS WAS LACKING MOISTURE AT THE SURFACE
WITH DEW POINTS IN THE HUDSON VALLEY TEN DEGREES BELOW THE AIR
TEMPERATURE AND ONLY A VERY LIGHT TRACE OF SNOW FELL IN THE ALBANY
AREA OVERNIGHT. FOR THE MOST PART VFR FLIGHT CONDITIONS WILL PREVAIL
WITH LOCALIZED MVFR LAKE AND TERRAIN CAUSED LOW CLOUDS AND SNOW
SHOWERS IN THE MOHAWK VALLEY...BERKSHIRES...AND THE SOUTHERN
GREEN MOUNTAINS OF VERMONT. WINDS EARLY THIS MORNING WERE LIGHT
FROM THE SOUTHWEST BUT ARE EXPECTED TO VEER WEST AND INCREASE TO
BETWEEN 10 AND 12 KNOTS BY MID MORNING WITH GUSTS AS HIGH AS 25
KNOTS IN THE ALBANY AREA RESULTING FROM FUNNELING DOWN THE MOHAWK
VALLEY. THE WINDS ARE LIKELY TO BRING A BROKEN TO OVERCAST DECK
AROUND 4500 FEET ASL OFF THE LAKE WITH CLEAR TO SCATTERED CLOUDS
NORTH AND SOUTH OF THE BAND OFF THE LAKE. LATE THIS AFTERNOON AS
THE HIGH BUILDS INTO THE REGION THE WINDS WILL SLACKEN TO 5 TO 10
KNOTS AND THE LOW CLOUDS IN THE MOHAWK VALLEY WILL BECOME SCATTERED
AS A BROKEN DECK OF MIDLEVEL CLOUDS MOVES IN FROM THE WEST. THESE
CLOUDS ARE FORECAST TO THICKEN AND LOWER FROM THE ALBANY AREA NORTH
TONIGHT BUT BECOME SCATTERED FARTHER SOUTH...WITH WINDS TONIGHT
BECOMING LIGHT FROM THE SOUTHWEST OR CALM.
OUTLOOK...
TUE...BECOMING MVFR/IFR WITH CHC OF SNOW...LOW CIGS AND VSBY IN PM.
WED...MVFR/IFR EARLY AM...LOW CIGS/VSBY AND CHANCE OF LINGERING
SHSN. THU...VFR/MVFR...CHANCE OF -SHSN.
FRI...VFR...NO SIG WX.
&&
.HYDROLOGY...
NO HYDRO PROBLEMS ARE EXPECTED THE NEXT SEVERAL DAYS. AN ARCTIC COLD
FRONT WILL MOVE THROUGH ON SATURDAY AND ANY PRECIPITATION FROM
SATURDAY INTO THE MIDDLE OF NEXT WEEK IS EXPECTED TO BE IN THE FORM
OF SNOW. WITH THE VERY COLD AIRMASS IN PLACE ACROSS THE REGION FROM
SATURDAY NIGHT THROUGH THE MIDDLE OF NEXT WEEK...THIS WILL RESULT IN
RAPID FORMATION OF ICE AGAIN ON THE MAIN STEM RIVERS IN THE HYDRO
SERVICE AREA.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...LAKE EFFECT SNOW ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
     NYZ032-038.
MA...NONE.
VT...NONE.
&&
$$
NEAR TERM...BGM
FOR THE LATEST UPDATES...PLEASE VISIT OUR WEBPAGE AT
WWW.WEATHER.GOV/ALBANY
</pre> ct
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
950 AM CST MON JAN 21 2008
.DISCUSSION...
CURRENT GRIDS LOOK TO BE IN GOOD SHAPE.  12Z KSHV RAOB SUGGESTS
AFTERNOON TEMPS TOPPING OUT IN THE LOWER TO MID 50S...BUT THIS SEEMS
UNREASONABLE...W/SHORTWAVE JUST ENTERING WESTERN ZONES...AND
ASSOCIATED CLOUD DECK PERSISTING THRU THE AFTERNOON.  KTXK REPORTING
UP ON THE LATEST OB...BUT LATEST RUC SOUNDINGS SUGGEST THIS WILL BE
BRIEF.  NO UPDATES.
&&
.AVIATION...
CLOUDS CONTINUE TO SPREAD OVER FORECAST AREA...WITH CIGS AROUND 5
THSD FT. CIGS WILL GRADUALLY LOWER THROUGHOUT THE DAY...EVENTUALLY
BECMG IFR AFTER 22/06Z AND CONTINUING UNTIL 22/18Z. VSBYS MOSTLY
VFR THROUGH 00Z...WITH AREAS OF MVFR FROM 00Z THROUGH 06Z...
THEN FREQUENT VSBYS 1-3 MI IN RAIN AND FOG FROM 06Z UNTIL 22/18Z.
WINDS SOUTHEAST 10-15 KTS THROUGHOUT THE PERIOD.
OUTLOOK FOR AFTER 22/18Z TUESDAY...MVFR DUE TO CIGS AND RAIN BUT
VSBYS GRADUALLY BECMG VFR ALL AREAS BY 23/00Z.
&&
.PREV DISCUSSION... /ISSUED 729 AM CST MON JAN 21 2008/
DISCUSSION...
QUICK ZONE UPDATE JUST SENT TO DROP TEMPORAL MENTION OF UNAUTHORIZED
SHOWERS OVER NE TX/WRN LA. BELIEVE SHOWERS SHOULD WEAKEN AS THEY MOVE
FARTHER E AWAY FROM BEST ISENTROPIC FORCING ASSOCIATED WITH THE SSW
LLJ OVER CNTRL TX...AT LEAST UNTIL LLJ AXIS NUDGES FARTHER E INTO E TX
LATE THIS AFTERNOON...AND ACROSS THE REMAINDER OF THE AREA TONIGHT.
SHOWERS DEVELOPING REMAIN VERY SHALLOW...ONLY SOME 5-6KFT DEEP...THUS
ONLY TRACE TO ONLY A FEW HUNDRETHS QPF AT MOST ARE EXPECTED UNTIL
LATER THIS AFTERNOON/TONIGHT.
UPDATE ALREADY OUT.
15
PREV DISCUSSION... /ISSUED 507 AM CST MON JAN 21 2008/
DISCUSSION...
EXTENSIVE LOW CLOUD DECK CONTINUES TO STREAM NE IN A HURRY ACROSS SE
OK/SW AR/E TX ALONG A 40-45KT SSW LLJ THIS MORNING...AND SHOULD
RAPIDLY ENCOMPASS THE REST OF SW AR/N LA BY MIDDAY. THE LLJ IS
ACTUALLY MIXING SOME OF THE WINDS DOWN TO THE SFC AS WELL...ESPECIALLY
OVER E TX...PUTTING THE BRAKES ON THE TEMPERATURE SLIDE...WITH TEMPS
EXPECTED TO SLOWLY WARM A FEW DEGREES BY SUNRISE. STEEP CAPPING
INVERSION ABOVE THE CLOUD LAYER WILL MAINTAIN THIS CLOUDINESS IN OVER
THE AREA TODAY...WITH PROGS CONTINUING TO INDICATE GOOD ISENTROPIC
FORCING ALONG THE 290-295K SURFACES ESPECIALLY OVER CNTRL TX
TODAY...GRADUALLY SHIFTING E INTO SE OK/EXTREME SW AR/WRN E TX BY LATE
THIS AFTERNOON. MEANWHILE...LEAD SHORTWAVE IS EJECTING E ACROSS AZ
THIS MORNING...AHEAD OF DEVELOPING CLOSED LOW OFF THE NRN CA COAST. AS
THIS SHORTWAVE IS ABSORBED INTO THE WESTERLIES TODAY...UPPER JET MAX
NEAR 140KTS WILL TRAVERSE E ACROSS TX BY THIS EVENING...WITH THE
REGION LYING IN THE LFQ OF THE MAIN JET OVERNIGHT ALONG THE AXIS OF
BEST ISENTROPIC FORCING ASSOCIATED WITH THE LLJ. FAVORABLE LAPSE RATES
IN THE 700-500MB LAYER DOES YIELD AN ISOLATED ELEVATED THUNDER THREAT
OVERNIGHT. THUS...EXPECTING SHOWERS/ISOLATED CONVECTION TO INCREASE IN
COVERAGE THIS EVENING...BUT STILL HAVE MY QUESTIONS AS TO EXACTLY HOW
EXTENSIVE COVERAGE WILL BE. THE MOISTURE PROFILE WILL BE SOMEWHAT
SHALLOW...AND THERE WILL BE A LACK OF LARGE SCALE FOCUSING
MECHANISMS...WITH OUR NEXT COLD FRONT STILL LYING IN WAIT FARTHER NW
ACROSS NRN OK/SE KS. THUS...THIS EVENT LOOKS TO BE ANOTHER HIGH
POP/LOW QPF EVENT...WITH RAINFALL AMOUNTS GENERALLY AROUND A QUARTER
OF AN INCH OR LESS.
NEXT LONGWAVE TROUGH WILL DROP SE INTO THE MS VALLEY TUESDAY...WHICH
WILL GIVE THIS NEXT COLD FRONT A PUSH SE TOWARDS THE AREA...NEARING
THE I-30 CORRIDOR OF NE TX/SW AR AROUND 12Z TUESDAY...SLIGHTLY FASTER
THAN THE ECMWF/NAM RUNS SUNDAY. HOWEVER...FRONT WILL BE SHALLOW...WITH
COLD ADVECTION LIKELY LAGGING THE FRONT A WAYS. THUS...AS DEEP LAYER
FLOW BECOMES WRLY BETWEEN 12-18Z...AND ENDING THE RAIN THREAT...COULD
SEE BREAKS IN THE LOW CLOUDS FOR TEMPS TO WARM IN WAKE OF THE FROPA.
NOT VERY CONFIDENT IN THE NUMBERS BEING SPIT OUT FOR MAX TEMPS
TUESDAY...THUS HAVE TRIMMED VALUES BACK A BIT NW OF I-30...AND
GENERALLY ACCEPTED THE NUMBERS ELSEWHERE AWAY FROM THE DEEPER COLD
AIR.
DESPITE A FAIRLY BENIGN WEDNESDAY FORECAST...THE SUBTROPICAL JET WILL
BECOME ACTIVE ONCE AGAIN...USHERING ABUNDANT ELEVATED PACIFIC MOISTURE
E ACROSS TX/LA AS EARLY AS TUESDAY NIGHT. THE GFS/ECMWF CONTINUES TO
GENERATE VERY LIGHT QPF AMOUNTS OVER E TX/N LA S OF I-20...MAINLY FROM
ELEVATED PRECIP. HOWEVER...COULD SEE ENOUGH OF THIS ELEVATED PRECIP
ACTUALLY REACH THE GROUND...AND FORECAST SOUNDINGS DO SUPPORT ENOUGH
EVAPORATIVE COOLING SUCH THAT IP COULD MIX IN WITH VERY -RA.
HOWEVER...BOTH MODELS ALSO SUGGEST A 2ND SHORTWAVE DROPPING SE ACROSS
THE MS VALLEY WEDNESDAY NIGHT...WHICH WOULD SHIFT MUCH COLDER/DRIER
AIR SE /OUR NEXT REINFORCING ARCTIC AIR MASS/ AND LIMIT ANY KIND OF
PRECIP. THUS...NOT ENOUGH CONFIDENCE ATTM TO ADD ANY WINTRY MIX TO THE
FORECAST GIVEN THIS SMALL TIMETABLE...BUT LATER SHIFTS WILL CONTINUE
TO MONITOR. IN ANY CASE...IT DOESN/T LOOK TO POSE A SIGNIFICANT THREAT
AS SFC TEMPS IN THESE AREAS SHOULD BE JUST ABOVE FREEZING WEDNESDAY
NIGHT.
A MORE SW FLOW ALOFT IS ESTABLISHED BY LATE THURSDAY UNDER THIS NEW
ARCTIC AIR MASS...ALTHOUGH DETAILS ARE A BIT SKETCHIER IN REGARDS TO THE
EVOLUTION/TRACK OF THE W COAST CLOSED LOW...WITH THE GFS MORE
AGGRESSIVE IN KICKING THIS LOW E LATE THURSDAY THAN THE MUCH SLOWER
ECMWF. IN ANY CASE...IT APPEARS ELEVATED PACIFIC MOISTURE WILL
INCREASE ONCE AGAIN LATE THURSDAY...WHICH COULD ALSO YIELD A WINTRY
MIX OVER MUCH OF THE AREA. HOWEVER...RETURN FLOW INCREASES BY THIS
TIME...WITH SRLY LLJ ESTABLISHED OVER TX. AMOUNT OF WARM ADVECTION
WILL DETERMINE WHETHER OR NOT A LIGHT WINTRY MIX WILL OCCUR...AND
STILL DO NOT HAVE ENOUGH CONFIDENCE TO ADD TO THE FORECAST
EITHER...GIVEN SO MANY UNCERTAINTIES. HOWEVER...THE GFS HAS REMAINED
CONSISTENT IN RECENT DAYS WITH THE EJECTION OF THE WEST COAST LOW INTO
THE WESTERLIES...SUCH THAT RAIN CHANCES WILL RETURN FOR MUCH OF NEXT
WEEKEND.
PRELIMS ARE LISTED BELOW.
15
AVIATION...
SC CONTINUES TO ROLL ACROSS E TX EARLY THIS MORNING...WITH BKN-OVC
CIGS AROUND FL060.  WITH SURFACE RIDGING NOW TO OUR E...BOUNDARY
LAYER WINDS SHOULD REMAIN SOUTHERLY THROUGH MOST OF TODAY.  AS
SUCH...I EXPECT THE CLOUD COVER TO WORK ITS WAY E.  JUST ABOUT ALL
TERMINALS SHOULD SEE VFR FLIGHT CATEGORIES THROUGH 22/0000 UTC...
WITH OVC CIGS AROUND FL050 OR HIGHER.
ISENTROPIC UPGLIDE IS SLATED TO RETURN TO E TX THIS AFTERNOON...AND
I WOULD NOT BE SURPRISED TO SEE ISOLATED -SHRA AT KLFK...KTYR...OR
KGGG AFTER 2100 UTC OR SO.  I AGREE WITH THE PUBLIC FORECASTER
THOUGH IN THAT MOST OF THE SHRA SHOULD WAIT UNTIL AFTER 22/0000 UTC
WHEN SLIGHTLY BETTER FORCING ARRIVES.  PRECIPITATION TIMING FOR THE
1200 UTC TAF PACKAGE LOOKS TO BE FAIRLY CLOSE TO ONGOING TAFS AND I
PROBABLY WILL NOT DEVIATE MUCH.  LOW CIGS SHOULD REDUCE FLIGHT
CATEGORIES TO IFR THIS EVENING FOR THE REMAINDER OF THE TAF PACKAGE.
OUTLOOK FOR TUESDAY...MVFR WITH REDUCTIONS TO IFR POSSIBLE.  /BUTTS/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV  49  44  55  31 /  20  60  30   0
MLU  50  42  55  32 /  10  50  50   0
DEQ  43  35  44  19 /  30  50  30   0
TXK  47  40  48  27 /  20  60  30   0
ELD  48  39  49  26 /  10  60  50   0
TYR  49  43  51  29 /  30  50  20   0
GGG  49  44  52  30 /  20  50  20   0
LFK  52  50  61  36 /  20  50  30   0
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&
$$
14/44
</pre> la
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GRAND FORKS ND
954 AM CST MON JAN 21 2008
.DISCUSSION...MAX TEMP FORECAST WHERE SKIES ARE CURRENTLY CLEAR
(ACROSS THE N FA) IN GOOD SHAPE. CURRENT TEMPS IN -10F TO -20F AND
EXPECT SOLAR TO PROVIDE 8F TO 13F RECOVERY.
CURRENT TEMPS WHERE SKIES ARE CURRENTLY CLOUDY (ACROSS THE S FA)
NOW ZERO TO -5F. CLOUDS EXPECTED TO EXIT MUCH OF THIS AREA BY
AFTERNOON...AND ENTIRE AREA BY LATE AFTERNOON. THINK AT LEAST 5F
RECOVERY POSSIBLE AND WILL RAISE MAX TEMPS ACCORDINGLY ACROSS THIS
AREA.
&&
.AVIATION...KFAR/KBJI WILL SEE SOME BROKEN SKIES THROUGH A GOOD
PORTION OF THE DAY. LIGHT FLURRIES WITH TEMPO VISIBILITIES DOWN TO
5 MILES POSSIBLE. BOTTOM LINE IS PREDOMINANTLY VFR CONDS THROUGH
PERIOD. KGFK SHOULD BE MOSTLY CLEAR THROUGH THE DAY.
&&
.PREV DISCUSSION... /ISSUED 906 AM CST MON JAN 21 2008/
UPDATE...CURRENT OBS INDICATE FLURRIES UNDER CLOUD COVER ACROSS
THE SOUTHERN FA. 12Z NAM/RUC SHOWING WEAK MID-LEVEL FRONTOGENESIS.
THIS FORCING WILL SLOWLY SHIFT SE THROUGH THE DAY ALONG WITH CLOUD
COVER. 12Z NAM/RUC A BIT SLOWER WITH SHIFTING CLOUD COVER TO THE
SE AND WILL ADJUST SKY GRIDS ACCORDINGLY. INTRODUCED FLURRIES.
DO NOT HAVE A GOOD HANDLE ON TEMPERATURE FOR TODAY...BUT CURRENT
MAXT GRID LOOKS REASONABLE. WILL UPDATE AGAIN IF TEMPS NEED
ADJUSTMENT.
PREV DISCUSSION... /ISSUED 359 AM CST MON JAN 21 2008/
DISCUSSION...
KEY CHALLENGE IN THE IMMEDIATE SHORT TERM WILL BE TEMPS THIS
MORNING AND MAX TEMPS DURING THE DAY TODAY. HAVE BEEN CLOUDY
ACROSS MOST OF THE FA THROUGHOUT THE NIGHT...WITH THE FAR NORTHERN
TIER COUNTIES BEGINNING TO THIN OUT AS OF 3 AM. TEMPS IN THE NORTHERN
COUNTIES WILL LIKELY DROP OFF A BIT MORE TONIGHT...BUT DO NOT
EXPECT THE REST OF THE AREA TO DROP MORE THAN 3 OR 4 DEG AFT
THE CLOUDS CLEAR OUT...THUS STARTING THE DAY OFF MUCH WARMER THAN PREV
FORECAST. WARMEST TEMPS TODAY WILL BE IN THE SOUTHWEST...WHERE
ABOVE ZERO TEMPS ARE VERY POSSIBLE.
NEXT CHALLENGE WILL BE LIGHT SNOW POTENTIAL FOR WAVE MOVING
THROUGH TONIGHT. GFS PROGGING SFC TROUGH TO PUSH THROUGH AFT
MIDNIGHT...ALTHOUGH NOT A LOT OF MOISTURE WITH IT. NAM CONTINUES
TO BE DRY. GOING WITH GFS...INTRODUCED A CHANCE OF LIGHT SNOW
MAINLY NORTH OF INTERSTATE 94...WITH NO MORE THAN A COUPLE OF
TENTHS OF ACCUMULATION LIKELY.
GFS HAS PUSHED FURTHER WEST THE CLIPPER SYSTEM MOVING THROUGH TUE
NIGHT. HAVE REDUCED POPS IN THE NORTHEAST AND PARTS OF THE EAST
ACCORDINGLY...AND ALSO REDUCED QPFS AND SNOWFALL ACCUMULATIONS AS
IT IS BEGINNING TO LOOK LIKE OUR SOUTHWESTERN AND SOUTHERN ZONES WILL
ONLY BE BRUSHED.
BEYOND TUESDAY...SHOULD SEE A LOT OF SUNSHINE AS RIDGE PUSHES IN
FROM WEST LATE IN THE WEEK. INCREASED MAX TEMPS A DEG OR TWO...BUT
STILL LOOKING LIKE HIGHS WILL BE PRIMARILY IN THE MID TEENS BY
THU. EXPANDED SLIGHT CHANCE OF LIGHT SNOW WEST TO INCLUDE ALL ZONES
WITH WAVE PUSHING ACROSS ON FRIDAY.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
TG
</pre> nd
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GRAND FORKS ND
906 AM CST MON JAN 21 2008
.UPDATE...CURRENT OBS INDICATE FLURRIES UNDER CLOUD COVER ACROSS
THE SOUTHERN FA. 12Z NAM/RUC SHOWING WEAK MID-LEVEL FRONTOGENESIS.
THIS FORCING WILL SLOWLY SHIFT SE THROUGH THE DAY ALONG WITH CLOUD
COVER. 12Z NAM/RUC A BIT SLOWER WITH SHIFTING CLOUD COVER TO THE
SE AND WILL ADJUST SKY GRIDS ACCORDINGLY. INTRODUCED FLURRIES.
DO NOT HAVE A GOOD HANDLE ON TEMPERATURE FOR TODAY...BUT CURRENT
MAXT GRID LOOKS REASONABLE. WILL UPDATE AGAIN IF TEMPS NEED
ADJUSTMENT.
&&
.AVIATION...KFAR/KBJI WILL SEE SOME BROKEN SKIES THROUGH A GOOD
PORTION OF THE DAY. LIGHT FLURRIES WITH TEMPO VISIBILITIES DOWN TO
5 MILES POSSIBLE. BOTTOM LINE IS PREDOMINANTLY VFR CONDS THROUGH
PERIOD. KGFK SHOULD BE MOSTLY CLEAR THROUGH THE DAY.
&&
.PREV DISCUSSION... /ISSUED 359 AM CST MON JAN 21 2008/
DISCUSSION...
KEY CHALLENGE IN THE IMMEDIATE SHORT TERM WILL BE TEMPS THIS
MORNING AND MAX TEMPS DURING THE DAY TODAY. HAVE BEEN CLOUDY
ACROSS MOST OF THE FA THROUGHOUT THE NIGHT...WITH THE FAR NORTHERN
TIER COUNTIES BEGINNING TO THIN OUT AS OF 3 AM. TEMPS IN THE NORTHERN
COUNTIES WILL LIKELY DROP OFF A BIT MORE TONIGHT...BUT DO NOT
EXPECT THE REST OF THE AREA TO DROP MORE THAN 3 OR 4 DEG AFT
THE CLOUDS CLEAR OUT...THUS STARTING THE DAY OFF MUCH WARMER THAN PREV
FORECAST. WARMEST TEMPS TODAY WILL BE IN THE SOUTHWEST...WHERE
ABOVE ZERO TEMPS ARE VERY POSSIBLE.
NEXT CHALLENGE WILL BE LIGHT SNOW POTENTIAL FOR WAVE MOVING
THROUGH TONIGHT. GFS PROGGING SFC TROUGH TO PUSH THROUGH AFT
MIDNIGHT...ALTHOUGH NOT A LOT OF MOISTURE WITH IT. NAM CONTINUES
TO BE DRY. GOING WITH GFS...INTRODUCED A CHANCE OF LIGHT SNOW
MAINLY NORTH OF INTERSTATE 94...WITH NO MORE THAN A COUPLE OF
TENTHS OF ACCUMULATION LIKELY.
GFS HAS PUSHED FURTHER WEST THE CLIPPER SYSTEM MOVING THROUGH TUE
NIGHT. HAVE REDUCED POPS IN THE NORTHEAST AND PARTS OF THE EAST
ACCORDINGLY...AND ALSO REDUCED QPFS AND SNOWFALL ACCUMULATIONS AS
IT IS BEGINNING TO LOOK LIKE OUR SOUTHWESTERN AND SOUTHERN ZONES WILL
ONLY BE BRUSHED.
BEYOND TUESDAY...SHOULD SEE A LOT OF SUNSHINE AS RIDGE PUSHES IN
FROM WEST LATE IN THE WEEK. INCREASED MAX TEMPS A DEG OR TWO...BUT
STILL LOOKING LIKE HIGHS WILL BE PRIMARILY IN THE MID TEENS BY
THU. EXPANDED SLIGHT CHANCE OF LIGHT SNOW WEST TO INCLUDE ALL ZONES
WITH WAVE PUSHING ACROSS ON FRIDAY.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
TG
</pre> nd
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
929 AM PST MON JAN 21 2008
UPDATED AVIATION
.DISCUSSION...ADVERTISED CHANGE IN THE WEATHER IS UNDERWAY AS
SHOWERS CONTINUE TO MOVE ONSHORE IN MOIST CYCLONIC FLOW. SHORT TERM
MODELS INCLUDING THE RUC13 ALL SEEM TO BE UNDERESTIMATING QPF IN
THE SHORT TERM. LOOKING AT MORNING SATELLITE THERE ARE NUMEROUS
SHOWERS OFFSHORE THAT WILL CONTINUE TO ROTATE ONSHORE THROUGH THE
DAY...SO IF ANYTHING AREAL COVERAGE SHOULD INCREASE THROUGH THE
DAY. SNOW LEVELS LOOKS TO BE AROUND 2500 FEET AT THIS TIME WITH
MEASURABLE SNOW REPORTED SO FAR ON TOP OF MOUNT HAMILTON AND IN THE
LOS PADRES FOREST OF MONTEREY COUNTY AT 3000 FEET. BODEGA BAY
PROFILER ESTIMATES SNOW LEVEL AT 2500 FEET AT THIS TIME. RAWS AT
ATLAS PEAK AND BEN LOMOND INDICATE SNOW LEVEL AT THE 2000-2500 FOOT
LEVEL. SNOW ADVISORY TO GO INTO EFFECT AT 4 PM FOR THE NORTH BAY
HILLS WITH ACCUMULATING SNOW EXPECTED ABOVE 1500 FEET AS QPF FIELD
AND COLDER TEMPS COME TOGETHER. WILL HAVE TO AT LEAST CONSIDER
HEADLINES FOR OUR OTHER HILL ZONES FOR THIS AFTERNOON AS MODELS
SEEM TO BE UNDERDOING QPF AND PERHAPS A BIT HIGH WITH SNOW LEVELS
AT THIS TIME.  SHOWER ACTIVITY WILL CONTINUE ON TUESDAY BUT SNOW
LEVELS WILL RISE AS THE FLOW ALOFT BECOMES MORE SOUTHWEST AS THE
UPPER LOW RESPONSIBLE FOR THE PRECIP DRIFTS FURTHER WESTWARD
OFFSHORE.
SHOWERS AND BELOW NORMAL DAYTIME HIGHS TO CONTINUE THROUGH MOST OF
THE WEEK AS THE UPPER LOW STAYS PARKED OFF THE COAST WITH RENEWED
SHORTWAVE ENERGY MOVING INTO THE TROUGH THROUGHOUT THE WEEK.
THE ECMWF AND GFS SHOW A STRONGER TROUGH BY THURSDAY NIGHT AND
FRIDAY WITH MORE WIDESPREAD AND HEAVIER RAIN LIKELY DURING THIS TIME
FRAME. WHEN ALL IS SAID AND DONE MANY OF THE COASTAL HILLS WILL END
UP WITH A PRETTY WET WEEK AS CONVECTIVE SHOWERS CONTINUE ON AND OFF
THROUGH THE PERIOD. SNOW LEVELS WILL OSCILLATE UPWARDS DURING THE
MID WEEK TIME FRAME BUT COULD GET BELOW 1500-2000 FEET AGAIN BY
SATURDAY AS THE CORE OF THE NEXT TROUGH PASSES OVERHEAD.
SOME HINT AT DRYING BY ABOUT THE SECOND HALF OF THE WEEKEND.
&&
.AVIATION...UPDATED TERMINALS TO REFLECT MORE OF A SE FLOW AT THE
SFC. HOWEVER...WINDS WILL BE SOMEWHAT PROBLEMATIC TODAY AS WEATHER
SYSTEM OFF THE COAST MAY BRIEFLY SWITCH WINDS TO THE SW.
OTHERWISE...A SHOWERY REGIME WILL DOMINATE THE REGION WITH
SCATTERED SHOWERS AND LOWERED CIGS.  SPECIFIC TIMING OF SHOWERS WILL
BE HARD AND HAVE USED MOSTLY TEMPOS.  BEST CHC FOR SHOWERS WILL BE
LATER IN THE DAY AND OVERNIGHT. CONFIDENCE IS MARGINAL.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
     4 PM TDA THROUGH 4 AM TUES...SNOW ADVISORY...N BAY MOUNTAINS.
&&
$$
PUBLIC FORECAST: R WALBRUN
AVIATION/MARINE: MEHLE
NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO
</pre> ca
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
915 AM PST MON JAN 21 2008
.DISCUSSION...ADVERTISED CHANGE IN THE WEATHER IS UNDERWAY AS
SHOWERS CONTINUE TO MOVE ONSHORE IN MOIST CYCLONIC FLOW. SHORT TERM
MODELS INCLUDING THE RUC13 ALL SEEM TO BE UNDERESTIMATING QPF IN
THE SHORT TERM. LOOKING AT MORNING SATELLITE THERE ARE NUMEROUS
SHOWERS OFFSHORE THAT WILL CONTINUE TO ROTATE ONSHORE THROUGH THE
DAY...SO IF ANYTHING AREAL COVERAGE SHOULD INCREASE THROUGH THE
DAY. SNOW LEVELS LOOKS TO BE AROUND 2500 FEET AT THIS TIME WITH
MEASURABLE SNOW REPORTED SO FAR ON TOP OF MOUNT HAMILTON AND IN THE
LOS PADRES FOREST OF MONTEREY COUNTY AT 3000 FEET. BODEGA BAY
PROFILER ESTIMATES SNOW LEVEL AT 2500 FEET AT THIS TIME. RAWS AT
ATLAS PEAK AND BEN LOMOND INDICATE SNOW LEVEL AT THE 2000-2500 FOOT
LEVEL. SNOW ADVISORY TO GO INTO EFFECT AT 4 PM FOR THE NORTH BAY
HILLS WITH ACCUMULATING SNOW EXPECTED ABOVE 1500 FEET AS QPF FIELD
AND COLDER TEMPS COME TOGETHER. WILL HAVE TO AT LEAST CONSIDER
HEADLINES FOR OUR OTHER HILL ZONES FOR THIS AFTERNOON AS MODELS
SEEM TO BE UNDERDOING QPF AND PERHAPS A BIT HIGH WITH SNOW LEVELS
AT THIS TIME.  SHOWER ACTIVITY WILL CONTINUE ON TUESDAY BUT SNOW
LEVELS WILL RISE AS THE FLOW ALOFT BECOMES MORE SOUTHWEST AS THE
UPPER LOW RESPONSIBLE FOR THE PRECIP DRIFTS FURTHER WESTWARD
OFFSHORE.
SHOWERS AND BELOW NORMAL DAYTIME HIGHS TO CONTINUE THROUGH MOST OF
THE WEEK AS THE UPPER LOW STAYS PARKED OFF THE COAST WITH RENEWED
SHORTWAVE ENERGY MOVING INTO THE TROUGH THROUGHOUT THE WEEK.
THE ECMWF AND GFS SHOW A STRONGER TROUGH BY THURSDAY NIGHT AND
FRIDAY WITH MORE WIDESPREAD AND HEAVIER RAIN LIKELY DURING THIS TIME
FRAME. WHEN ALL IS SAID AND DONE MANY OF THE COASTAL HILLS WILL END
UP WITH A PRETTY WET WEEK AS CONVECTIVE SHOWERS CONTINUE ON AND OFF
THROUGH THE PERIOD. SNOW LEVELS WILL OSCILLATE UPWARDS DURING THE
MID WEEK TIME FRAME BUT COULD GET BELOW 1500-2000 FEET AGAIN BY
SATURDAY AS THE CORE OF THE NEXT TROUGH PASSES OVERHEAD.
SOME HINT AT DRYING BY ABOUT THE SECOND HALF OF THE WEEKEND.
&&
.AVIATION...SCATTERED SHOWERS ARE EXPECTED AT ALL TERMINALS TODAY
WITH VARIABLE CIGS AROUND 3000 FT. WINDS ARE EXPECTED TO BE LIGHT
WESTERLY.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
     4 PM TDA THROUGH 4 AM TUES...SNOW ADVISORY...N BAY MOUNTAINS.
&&
$$
PUBLIC FORECAST: R WALBRUN
AVIATION/MARINE: ANDERSON/MEHLE
NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO
</pre> ca
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1157 AM CST MON JAN 21 2008
.DISCUSSION...
ISSUED 1115 AM CST MON JAN 21 2008
UPDATED THE FORECAST TODAY TO ADJUST SKY COVER WITH MORE SUNSHINE
SE OF THE IL RIVER LATE THIS MORNING AND INCREASING CLOUDS DURING
THE AFTERNOON. CONTINUED 20 TO 30 CHANCE OF LIGHT SNOW LATE THIS
AFTERNOON NW OF THE IL RIVER. INCREASED SSE WINDS TODAY TO BREEZY
LEVELS FROM 15 TO 25 MPH. HIGHS GET CLOSER TO NORMAL TODAY IN THE
UPPER 20S FROM I-74 NE AND 30 TO 35F SW OF I-74.
17Z/11 AM SURFACE ANALYSIS SHOWS 1045 MB MODIFIED ARCTIC HIGH
PRESSURE OVER THE MID ATLANTIC STATES BY VA/NC. A 1020 MB LOW
PRESSURE WAS OVER NORTH CENTRAL KS WITH IS WARM FRONT EXTENDING
OVER FAR SE IA INTO NORTHERN IL JUST NORTH OF GALESBURG...LACON
AND KANKAKEE. AREA OF LIGHT SNOW AND FLURRIES NORTH OF THIS WARM
FRONT...NORTH OF I-88 IN FAR NORTHERN IL THIS MORNING AND OVER
CENTRAL AND NORTHERN IA. INCREASING PRESSURE GRADIENT OVER CENTRAL
IL DURING THIS MORNING INCREASING SSE WINDS TO BREEZY LEVELS FROM
15 TO 25 MPH. BROKEN MID LEVEL CLOUDS ALONG AND NW OF THE IL RIVER
WHILE SUNNY SKIES ALONG AND SE OF I-55. TEMPS HAVE MODIFIED INTO
THE LOW TO MID 20S. DEWPOINTS REMAIN QUITE LOW IN THE SINGLE
DIGITS REFLECTING VERY DRY LOWER LEVELS OVER CENTRAL/SE IL.
RUC AND WRF MODELS KEEP CENTRAL IL DRY THROUGH 00Z/6 PM...WITH
QPF/LIGHT SNOW STAYING NW OF GALESBURG AS LOW PRESSURE OVER NORTH
CENTRAL KS MOVES INTO NORTH CENTRAL MO. BUT SHEF MODEL BRINGS SOME
LIGHT QPF/LIGHT SNOW INTO KNOX AND STARK COUNTY BETWEEN 21Z AND
00Z (3 TO 6 PM). DECIDED TO HOLD ONTO 20 TO 30 CHANCE OF LIGHT
SNOW NW OF THE IL RIVER BUT DURING LATE AFTERNOON. MID AND
EVENTUALLY LOW CLOUDS WILL INCREASE FROM THE WEST DURING THE
AFTERNOON...WITH SE IL ENJOYING THE MOST SUNSHINE TODAY. LOW
PRESSURE TO MOVE ACROSS NORTHERN IL OVERNIGHT SPREADING LIGHT SNOW
ACROSS THE STATE TONIGHT WITH 1 TO 2 INCHES LIKELY. BREEZY SSE WINDS
15 TO 25 MPH COMBINED WITH SOME SUNSHINE ESPECIALLY FROM I-55 SE
WILL BUMP HIGHS CLOSER TO NORMAL THIS AFTERNOON. HIGHS RANGE FROM
THE UPPER 20S FROM I-74 NE AND 30 TO 35F SW OF I-74...WITH FAR SW
AREAS FROM WINCHESTER TO LAWRENCEVILLE APPROACHING 35F.
HUETTL
&&
.AVIATION...
ISSUED 1155 AM CST MON JAN 21 2008 VFR CONDITIONS THIS AFTERNOON
WILL DETERIORATE TONIGHT ESPECIALLY BY LATE EVENING INTO OVERNIGHT
AS LIGHT SNOW DEVELOPS ACROSS CENTRAL IL. THIS IN RESPONSE TO 1021
MB LOW PRESSURE OVER NE KS DEEPENING AS IT TRACKS NE ACROSS
NORTHERN IL OVERNIGHT. LOW DEEPENS TO 1008 MB JUST EAST OF
GEORGIAN BAY CANADA BY 18Z/TUE WHILE SWINGING A COLD FRONT THROUGH
IL EARLY TUE MORNING. MID LEVEL CLOUDS FROM 6 TO 10K FT FROM THE
IL RIVER VALLEY TO SPREAD EAST ACROSS CENTRAL IL DURING THIS
AFTERNOON. LOW CLOUDS OF 3 TO 5K FT OVER CENTRAL MO TO SPREAD EAST
ACROSS CENTRAL IL EARLY THIS EVENING AFTER SUNSET. LOW CLOUDS OF 1
TO 2K FT WILL MOVE IN FROM 04Z TO 07Z AS LIGHT SNOW DEVELOPS AND
REDUCES VISIBILITIES TO 1 TO 3 MILES. IFR TO LIFR CIELINGS AND
VSBYS WILL BE POSSIBLE OVERNIGHT FROM 06Z TO 12Z WITH HEAVIER SNOW
SHOWERS ESPECIALLY AT PIA AND BMI. BREEZY SSE WINDS THIS AFTERNOON
WITH GUSTS OF 18 TO 24KTS TO TURN SSW TONIGHT AROUND 15 KTS AND
THEN WEST BEHIND THE COLD FRONT EARLY TUE MORNING WITH GUSTS
AROUND 20 KTS.
HUETTL
&&
.PREV DISCUSSION...
ISSUED 306 AM CST MON JAN 21 2008
SHORT TERM...TODAY THROUGH WEDNESDAY.
SFC RIDGE AXIS HAS SHIFTED JUST NORTHEAST OF THE AREA THIS
MORNING... AND AS EXPECTED... LOW LEVEL WARM ADVECTION HAS RESULTED
IN A SLOW BUT STEADY INCREASE IN MID-LEVEL CLOUD COVER OVERNIGHT
ACROSS MUCH OF THE NORTHERN HALF OF THE CWA... WHICH HAS ALLOWED
TEMPERATURES TO REMAIN COMPARATIVELY MILD COMPARED TO THE LAST
COUPLE OF MORNINGS. LIGHT SNOW ACTIVITY HAS REMAINED NORTH OF THE
AREA OVERNIGHT AS EXPECTED... WITH THE STEEPEST ISENTROPIC ASCENT
FOCUSED WELL TO OUR WEST. EVEN SO... WEAK RADAR RETURNS SUGGEST A
FEW FLURRIES WILL BE POSSIBLE EARLY THIS MORNING NORTH AND WEST OF
THE ILLINOIS RIVER... BUT LITTLE ELSE.
FORECAST IN THE NEAR TERM HAS BEEN REMARKABLY WELL BEHAVED OVER THE
PAST FEW DAYS... AND THERE IS STILL LITTLE CHANGE IN THE FORECAST
PHILOSOPHY THROUGH WEDNESDAY. LOW LEVEL WARM ADVECTION TODAY WILL
BRING A BRIEF RESPITE FROM THE BITTER COLD AIRMASS THAT SETTLED IN
ACROSS THE AREA THIS PAST WEEKEND... BUT WEAK SFC WAVE AND ATTENDANT
COLD FRONT WILL MOVE ACROSS THE AREA TONIGHT...BRINGING A BRIEF
PERIOD OF LIGHT SNOW TO MOST AREAS OF THE CWA...AND DRAGGING THE
COLDER AIR BACK IN BEHIND IT.
SYSTEM TONIGHT CONTINUES TO LOOK LOOSELY ORGANIZED AND RELATIVELY
PROGRESSIVE... WITH WEAK LIFT PROGRESSING WEST TO EAST FROM THIS
EVENING INTO TUESDAY MORNING. LACK OF MID-LEVEL MOISTURE AND ANY
REALLY STRONG LIFT WILL HELP KEEP QPF AMOUNTS DOWN... AND AS HAS
BEEN MENTIONED THE PAST COUPLE OF DAYS... THERE REALLY IS NO
STANDOUT AREA WITH HIGHER SNOWFALL POTENTIAL OVER ANY OTHER.
OVERALL... EXPECT ANYWHERE FROM A HALF INCH TO 2 INCHES OF SNOW WITH
A GENERAL NORTHWEST-SOUTHEAST GRADIENT.  HIGHER AMOUNTS NORTHWEST OF
THE SFC WAVE TRACK... I.E. NORTHWEST OF THE ILLINOIS VALLEY.
FORECAST SOUNDINGS EARLIER LOOKED SOMEWHAT MARGINAL FOR KEEPING ICE
CRYSTALS IN THE CLOUD LAYER BEYOND MIDNIGHT ACROSS WESTERN AND
SOUTHERN SECTIONS... BUT IT APPEARS NOW WE SHOULD REMAIN SATURATED
UP TO ABOUT THE -10C LEVEL... WHICH REMAINS A LITTLE MARGINAL.
CONSIDERING THE LACK OF STRONG LIFT AS WELL... WILL KEEP IN A
MENTION OF PATCHY FREEZING DRIZZLE AFTER MIDNIGHT IN THE SOUTHWEST
CORNER OF THE CWA... ALTHOUGH THIS IS NOT EXPECTED TO BE A MAJOR
HAZARD.
LIGHT SNOW PACK...PRESUMABLY MOST PREVALENT IN THE NORTHWEST...WILL
LEAD TO ANOTHER FRIGID MORNING ON WEDNESDAY... WITH BELOW ZERO
READINGS POSSIBLE AGAIN. CLIPPER SYSTEM APPROACHES WEDNESDAY
AFTERNOON... STILL LOOKING FAIRLY WEAK AND VERY PROGRESSIVE...WITH
NO MAJOR SNOW ACCUMULATIONS EXPECTED WITH IT AT THIS TIME.
LONG TERM...THURSDAY THROUGH SUNDAY.
PATTERN WILL SHIFT BY THE END OF THE WORKWEEK AS THE TROUGH THAT HAS
BEEN CARVED OUT ACROSS THE NORTHEASTERN CORNER OF THE CONTINENT
FINALLY BREAKS DOWN... RESULTING IN A MORE PROGRESSIVE AND MILDER
PATTERN HEADING INTO THE WEEKEND. MODELS HAVE BEEN HAVING SOME
PROBLEMS WITH THE HANDLING OF A DEEPENING TROUGH OFF THE WEST COAST
BEYOND THE DAY 4 TIMEFRAME... AND THIS HAS EVENTUAL IMPACTS ON OUR
WEATHER HEADING TOWARDS THE END OF THE WEEKEND...DEPENDING ON THE
EVOLUTION AND POSSIBLE EASTWARD EJECTION OF THE WEST COAST TROUGH.
HOWEVER... THIS DOES NOT APPEAR TO HAVE MUCH IMPACT IN THE DAYS 1-5
TIMEFRAME.
HARDIMAN
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
</pre> il
AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE MARQUETTE MI
1223 PM EST MON JAN 21 2008
UPDATED FOR 18Z TAF DISCUSSION
.SYNOPSIS...
08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS CONTINUES TO SHOW
AN AMPLIFIED PATTERN ACROSS NORTH AMERICA...WITH STRONG RIDGING FROM
THE EAST PACIFIC INTO NW CANADA...TROUGHING OVER THE PACIFIC NW...
AND A BROAD UPPER TROUGH OVER THE EAST HALF OF CANADA. NW UPPER FLOW
WHICH HAS BEEN OVER UPPER MI THE PAST FEW DAYS IS TURNING MORE
WESTERLY...DUE TO THE COMBINATION OF THE DIGGING PACIFIC NW TROUGH
AND A SHRTWV DROPPING SOUTH INTO SOUTHERN SASKATCHEWAN. THIS
WESTERLY FLOW IS GRADUALLY BRINGING WARMER AIR INTO UPPER MI AS
NOTED BY 850MB TEMP RISES OF 4C AT MPX AND INL BETWEEN 12Z AND 00Z.
HOWEVER...THE AIRMASS STILL REMAINS COLD...GIVEN THE -24C READING AT
INL AND -19C AT MPX. THUS...LAKE EFFECT CONTINUES OFF LAKE SUPERIOR.
HOWEVER...THE BANDS ARE BECOMING MORE EAST-WEST ORIENTED THANKS TO
THE UPPER LEVEL HEIGHT RISES SUPPORTING MORE WESTERLY LOW LEVEL
FLOW...IN ADDITION TO LAND BREEZES WHICH HAVE DEVELOPED. TEMPS
INLAND HAVE DROPPED INTO THE TEENS BELOW ZERO...BUT HAVE NOT DROPPED
MUCH MORE DUE TO INCREASING HIGH CLOUDS IN THE UPPER FLOW. TO THE
WEST...A FAIRLY POTENT SHRTWV CAN BE SEEN CROSSING NEVADA.
DOWNSLOPING WESTERLY FLOW AHEAD OF THIS SHRTWV HAS CAUSED PRESSURE
FALLS IN THE TEXAS PANHANDLE. FROM THE DEVELOPING LOW PRESSURE...A
WARM FRONT EXTENDS NE INTO SW IOWA.
&&
.DISCUSSION...
MAIN FORECAST CONCERN IS SNOWFALL OVER THE KEWEENAW THROUGH TONIGHT.
TODAY...SHRTWV OVER NEVADA WILL HEAD OUT INTO THE CENTRAL PLAINS...
CAUSING THE TEXAS PANHANDLE LOW TO LIFT UP TOWARDS KANSAS CITY.
MEANWHILE TO OUR NW...THE SHRTWV TROUGH OVER SOUTHERN SASKATCHEWAN
IS PROGGED TO DROP DOWN INTO NORTH DAKOTA AND NW MN. THE COMBINATION
OF BOTH FEATURES WILL RESULT IN THE UPPER FLOW TURNING SW...MORE
FAVORABLE FOR BRINGING WARMER AIR INTO THE CWA. IN FACT...MODELS
BRING 850MB TEMPS UP ABOUT 4C FROM CURRENT READINGS. THIS MAY NOT
SEEM LIKE A WHOLE LOT...BUT IT SHOULD PRODUCE A MORE FAVORABLE
ENVIRONMENT FOR DENDRITES COMPARED TO THE RECENT SMALLER SNOWFLAKES.
THIS WILL PLAY A ROLE IN TWO DIFFERENT AREAS OF CONCERN. THE FIRST
CONCERN IS THE POSSIBILITY OF SYNOPTIC PCPN WITH THE LOW LIFTING UP
TOWARDS KANSAS CITY. MODELS DEPICT MID-LEVEL FRONTOGENESIS
INCREASING OVER CENTRAL WI INTO NORTHERN LOWER MI DURING THE AFTN.
GIVEN THE LOCATION OF THIS AXIS...AND THE PRESENCE OF A 120-130 JET
STRETCHING FROM UPPER MI EASTWARD...FAVORING UPPER DIVERGENCE SOUTH
OF THE CWA...THINK MUCH OF THE PCPN SHOULD STAY TO THE SOUTH. DRY
AIR PRESENT OVER THE CWA AS INDICATED BY THE 00Z INL AND GRB
SOUNDINGS SHOULD ALSO HOLD SYNOPTIC PCPN FROM MARCHING NORTH. WILL
MAINTAIN CHANCE POPS...BUT RESTRICT THEM JUST TO THE SOUTH CENTRAL.
THE OTHER PCPN CONCERN IS LAKE EFFECT SNOW. FOR THE EASTERN
CWA...SOME LAKE EFFECT MIGHT LINGER FOR A FEW MORE HOURS PAST THE
END TIME OF THE ADVISORY...BUT SEE NO NEED TO EXTEND THE ADVISORY AT
THE PRESENT TIME. OVER THE KEWEENAW...LOW LEVEL WINDS ARE PROGGED TO
BACK A LITTLE MORE SW THAN PREVIOUSLY THOUGHT...WHICH COULD MOVE THE
CURRENT LAKE EFFECT COMPLETELY OFFSHORE FOR SOME OF THE KEWEENAW
THIS AFTERNOON. THIS IS INDICATED BY THE NAM/GFS/LOCAL WRF-ARW RUN.
HOWEVER...THE LOCAL WRF-ARW RUN DOES MANAGE TO BRING A CONVERGENT
BAND BACK INTO THE KEWEENAW AFTER 20Z. FEEL THIS SOLUTION MIGHT BE
THE BEST TO FOLLOW AS IT USUALLY HAS A BETTER HANDLE ON THE LAKE
AGGREGATE. SOUNDINGS DEPICT AT LEAST SOME DENDRITIC GROWTH BETWEEN
THE CLOUD BASE AND 850MB...WHICH MEANS WHEN THE CONVERGENT BAND
MOVES IN...THERE COULD BE SOME DECENT SNOWFALL RATES.
THEREFORE...HAVE LEFT THE GOING ADVISORY INTACT. GIVEN WARMER AIR
MOVING IN...WARMER TEMPS ARE EXPECTED TODAY. ONLY MADE MINOR
ADJUSTMENTS TO HIGHS.
TONIGHT...SHRTWV TROUGH OVER NORTH DAKOTA IS PROGGED TO SHIFT EAST
TOWARDS WESTERN LAKE SUPERIOR BY 12Z TUE. THIS TROUGH SHOULD HELP
PROMOTE A RAPID PROGRESSION OF THE SHRTWV LIFTING UP FROM THE
CENTRAL PLAINS...AND FAVOR THE GFS/UKMET IDEA OF BRINGING THE SHRTWV
INTO LOWER MI BY 12Z WITH A WEAKER SFC LOW SITUATED NEAR ALPENA AT
THE SAME TIME. THIS IS ALSO FAVORED BY HPC. MID-LEVEL FRONTOGENESIS
AND UPPER DIVERGENCE FIELDS FROM THE GFS STILL SUGGEST THE BEST
FORCING FOR PCPN TO REMAIN TO THE SOUTH...THOUGH ENOUGH CONFIDENCE
EXISTS TO RAISE POPS TO LIKELY IN SOUTHERN MNM COUNTY. THE REST OF
THE CWA WILL HAVE LOW CHANCE POPS...AND BOTH AREAS ARE FOR MAINLY IN
THE EVENING AS THE MAIN MID-LEVEL FRONTOGENESIS AREA SHIFTS EAST
AFTER 06Z. NEXT CONCERN IS WITH THE SHRTWV TROUGH...AS 850MB TEMPS
FALL 1-2C. LOW LEVEL FLOW TURNS MORE WESTERLY IN THE EVENING...SO
THE LAKE EFFECT BAND ENTERING THE KEWEENAW THIS AFTERNOON SHOULD
REMAIN FAIRLY PROGRESSIVE...STALLING OUT AND WEAKENING OVER
ONTONAGON COUNTY LATER IN THE NIGHT. HAVE EXTENDED THE ADVISORY FOR
THE KEWEENAW TO 06Z TONIGHT TO ACCOUNT FOR THE LAKE EFFECT BAND. TO
THE EAST...THE SWITCH TO MORE WEST TO EVEN NW WILL BRING THE EASTERN
EXTENT OF THE BAND DOWN INTO LUCE/ALGER COUNTIES...FOLLOWED BY THE
TYPICAL ONTARIO LAND BREEZE CONVERGENT BAND FROM NE LAKE SUPERIOR
INTO LUCE COUNTY. THE REST OF THE CWA SHOULD SEE SOME CLEARING
DURING THE OVERNIGHT HOURS TO ALLOW TEMPS TO FALL. WILL TREND TEMPS
DOWNWARD GIVEN THIS CLEARING POSSIBILITY AND A DRY AIRMASS IN PLACE.
TUE...SHRTWV TROUGH SWINGS INTO UPPER MI. WITH THIS TROUGH COMES
ANOTHER COOL BLAST OF AIR...WITH 850MB TEMPS OF -24 TO -26C ENTERING
WESTERN LAKE SUPERIOR BY 00Z WED. THUS...MORE LAKE EFFECT IS
EXPECTED. SURFACE PATTERN SHOWS LAKE INDUCED TROUGHING SETTING
UP...WITH LOW PRESSURE NEAR WHITEFISH POINT AND A TROUGH EXTENDING
WEST THROUGH TWIN LAKES. THE HEAVIEST LAKE EFFECT SNOW...WHICH WILL
NOT BE ALL THAT HEAVY GIVEN THE COLD AIR MOVING IN REDUCING SNOW TO
WATER RATIOS...WILL BE CONFINED TO THE TROUGH AS IT PROVIDES A
SOURCE OF CONVERGENCE. THUS...AGAIN THE WESTERN U.P. AND THE AREA
FROM ALGER INTO NORTHERN LUCE COUNTY IS EXPECTED TO BE UNDER THE GUN
FOR SNOW. DRY WEATHER IS EXPECTED FOR THE REST OF THE CWA...WITH
TEMPS FAIRLY SIMILAR TO THOSE ON MON. TEMPS COULD FALL LATE IN THE
DAY AS THE COLDER AIR MOVES IN.
TUE NIGHT INTO WED...SHRTWV TROUGH HEADS OFF TOWARDS QUEBEC TUE
NIGHT WHILE ANOTHER SHRTWV TROUGH DROPS SOUTH THROUGH SOUTH CENTRAL
CANADA. THIS SECOND SHRTWV TROUGH...WITH A LITTLE MORE OF A COLD AIR
PUNCH...SHOULD ENTER UPPER MI DURING THE DAY WED. THUS...CONTINUED
LAKE EFFECT WITH CONTINUED BELOW NORMAL TEMPERATURES ARE EXPECTED.
WIND FLOW DOES TURN A BIT MORE NORTHERLY WITH THE SECOND SHRTWV
TROUGH WEDNESDAY MORNING...WHICH MEANS MARQUETTE AND WESTERN ALGER
COUNTIES MAY PICK UP SOME SNOW. HOWEVER...THE MORE NORTHERLY WINDS
DO NOT LAST LONG...AS MODELS SHOW ANY LAKE EFFECT BANDS HEADING OFF
TOWARDS EASTERN ALGER COUNTY LATER WED AFTERNOON. EITHER WAY...IT
STILL LOOKS LIKELY THAT ALL OF THE WESTERN COUNTIES WILL PICK UP
MORE SNOW...THOUGH AGAIN WITH THE COLD 850MB TEMPS (DROPPING TO
AROUND -26C BY 18Z WED) SUGGESTS FINER SNOWFLAKES. ONLY MINOR TWEAKS
WERE MADE TO THE GOING LOW AND HIGH TEMPS.
WED NIGHT INTO THU...THE PATTERN STARTS TO CHANGE DURING THIS
PERIOD...AS THE SHRTWV TROUGH OVER THE CWA DIGS DOWN TOWARDS THE
OHIO VALLEY AND THE CURRENT EAST PACIFIC RIDGE GETS PUSHED EASTWARD
TOWARDS THE CWA. HOWEVER...850MB TEMPS EVEN AT 18Z THU ARE STILL
DEPICTED BELOW -18C. NOT UNTIL 00Z DO 850MB TEMPS START TO GET WARM
ENOUGH OVER WESTERN LAKE SUPERIOR TO ALLOW LAKE EFFECT TO END (-8 TO
-10C) THUS...WITH WNW WINDS THROUGH THIS PERIOD...MORE LAKE EFFECT
SNOW IS EXPECTED FOR THE WESTERN U.P. AND ALGER INTO NORTHERN LUCE
COUNTIES. TEMPS COULD GET QUITE CHILLY WED NIGHT IF SKIES CAN
CLEAR...AS NOTED BY MEX COOP GUIDANCE OF -20F AT CHAMPION. ALTHOUGH
WE ARE WARM ADVECTING ON THU...TEMPS WILL STRUGGLE TO GET MUCH
HIGHER THAN THE LOW TEENS...IF EVEN 10 ABOVE IN INLAND LOCATIONS.
BEYOND THU...THE EAST PACIFIC RIDGE BUILDS INTO THE CWA FOR
FRI...CAUSING 850MB TEMPS TO CLIMB TO PERHAPS AS HIGH AS -4C. MEX
GUIDANCE RESPONDS ACCORDINGLY BY SHOWING HIGH TEMPS IN THE MID 20S.
GIVEN THE GOOD AGREEMENT WITH THE 00Z ECMWF...HAVE RAISED HIGHS A
FEW DEGREES. NO OTHER CHANGES MADE BEYOND FRIDAY.
&&
.AVIATION (FOR THE 18Z TAF ISSUANCE)...
LAKE EFFECT SNOW HAS TEMPORARILY ENDED AT KCMX AS WINDS ARE SW AND
WILL KEEP BANDS OFFSHORE AND THIS SHOULD CONTINUE TO BRING VFR
CONDITIONS INTO THE AFTERNOON. WINDS BECOME WESTERLY THIS
EVENING...SO IFR CONDITIONS RETURN THROUGH TONIGHT INTO TUE MORNING
AT KCMX. VFR CONDITIONS EXPECTED AT KSAW THROUGH THE PERIOD EXCEPT
COULD GO MVFR WITH LIGHT SNOW LATE THIS AFTERNOON THROUGH THIS
EVENING ON THE NORTHERN FRINGE OF THE SYSTEM PASSING TO THE SOUTH.
&&
.MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)...
WEST TO NORTHWEST WINDS IN THE 15 TO 30 KT RANGE WILL GRADUALLY BACK
TO SOUTHWEST OR WEST AS A TIGHT GRADIENT PERSISTS BETWEEN
ARCTIC HIGH PRESSURE BUILDING SOUTHEAST FROM THE PLAINS AND A
LINGERING TROUGH INTO THE UPPER GREAT LAKES. LOW PRESSURE WILL MOVE
FAR ENOUGH SOUTH OF THE AREA SO THAT LAKE INDUCED TROUGHING TONIGHT
INTO TUE WILL KEEP MAINLY W OR WSW WINDS GOING OVER THE SOUTH
PORTION OF THE LAKE AND NW WINDS OVER THE NORTH HALF WITH WIND
VALUES MAINLY IN THE 15 TO 25 KT RANGE. A COLD FRONT WILL MOVE
THROUGH TUESDAY NIGHT WITH WINDS VEERING NORTHERLY BY WED. HEAVY
FREEZING SPRAY WILL CONTINUE THIS MORNING DUE TO THE STRONG WINDS
AND VERY COLD ARCTIC AIR. HEAVY FREEZING SPRAY WILL AGAIN DEVELOP
TUESDAY NIGHT INTO WEDNESDAY AS A REINFORCING BATCH OF ARCTIC AIR
AND STRONGER WINDS MOVES IN.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
MICHIGAN...
  LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 1 AM EST
    TUESDAY FOR MIZ001-003.
  LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST THIS
    MORNING FOR MIZ002.
  LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 5 AM EST EARLY
    THIS MORNING FOR MIZ006-007.
LAKE SUPERIOR...
  HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST THIS AFTERNOON FOR
     LSZ162-263>267.
LAKE MICHIGAN...
  HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST THIS MORNING FOR
     LMZ248-250.
&&
$$
SYNOPSIS/DISCUSSION...AJ
AVIATION...MICHELS
MARINE...JLB
</pre> mi
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
308 PM CST MON JAN 21 2008
.DISCUSSION...
INTERESTING SNOW EVENT UNFOLDING ACROSS THE SOUTHERN AND
SOUTHEASTERN SECTIONS OF THE FORECAST AREA TODAY...AND MAIN
FORECAST CONCERN REVOLVES AROUND HOW IT WILL EVOLVE OVER THE REST
OF THE AFTERNOON AND INTO THE EVENING HOURS.
WIDESPREAD AREA OF APPROXIMATELY 2 INCH SNOW AMOUNTS HAVE BEEN
RECEIVED FROM SPOTTERS THIS AFTERNOON...TO THE SOUTH OF AN
OWATONNA TO SAINT JAMES LINE. MORE LOCALIZED AREA OF 3 TO 4 INCH
AMOUNTS SEEN IN FARIBAULT...FREEBORN...AND STEELE
COUNTIES...ASSOCIATED WITH HIGH REFLECTIVITY BAND THAT MOVED
NORTHWARD INTO SOUTHERN MINNESOTA AND STRENGTHENED UPON DOING SO.
NAILING DOWN SNOW AMOUNTS HAS BEEN QUITE TRICKY...WITH HIGHER
REFLECTIVITIES ASSOCIATED WITH LARGE FLAKES...WITH SMALL GRANULAR
PRECIPITATION PARTICLES IN THE LOWER REFLECTIVITIES. RADAR TRENDS
HAVE SHOWN THAT THIS WARM ADVECTION INDUCED HIGHER REFLECTIVITY
BAND IS SHIFTING MORE INTO SOUTHEAST MINNESOTA/SOUTHWEST
WISCONSIN...SO ADDITIONAL RAPID ACCUMULATION IS NOT EXPECTED.
RUC/NAM FORECASTS...COMBINED WITH RADAR SIGNALS...INDICATE THAT
DEFORMATION/MID LEVEL FRONTOGENESIS IS TAKING OVER AS THE MAIN
FORCING MECHANISM...LIKELY RESULTING IN SMALLER GRAINS/FLAKES.
SOME CONTEMPLATION OCCURRED REGARDING A POSSIBLE UPGRADE TO A
HEAVY SNOW WARNING FOR A SMALL PORTION OF SOUTH CENTRAL MINNESOTA
/OWATONNA TO ALBERT LEA/...WHERE FRONTOGENESIS AND RELATED OMEGA
PROGS SHOW THE MOST FAVORABLE LOCATIONS FOR ADDITIONAL
ACCUMULATION...ABOVE WHAT HAS FALLEN AND WILL CONTINUE TO FALL FOR
THE REMAINDER OF THIS AFTERNOON. WITH SMALLER SNOWFALL RATES
EXPECTED...AS DISCUSSED ABOVE...COORDINATION WITH DMX AND ARX
SOLIDIFIED THE INITIAL LEANINGS TO STAYING WITH THE ADVISORY. IT
WILL BE CLOSE...HOWEVER. SNOW SHOULD LARGELY TAPER BY
MIDNIGHT...AS THE SURFACE LOW SHIFTS INTO NORTHWESTERN
ILLINOIS...CONTINUING ITS EASTWARD PUSH.
NEXT ISSUES TONIGHT ARE TEMPERATURES AND RESULTANT WIND CHILLS. WE
SHOULD SEE SOME BREAKS IN THE CLOUDS...AND WITH MUCH LOWER DEW
POINTS/TEMPERATURES UPSTREAM...TEMPERATURES SHOULD DO SOME
BOTTOMING OUT OVER THE NORTHERN PART OF THE FORECAST
AREA...ESPECIALLY IN THE AXN/LXL REGION. LOW LEVEL WARM ADVECTION
IN ADVANCE OF THE NEXT CLIPPER SYSTEM WILL QUICKLY ENSUE LATE
TONIGHT...LEADING TO A RISE IN TEMPERATURES AFTER MIDNIGHT. WINDS
WILL BE AROUND 10 MPH FOR MUCH OF THE NIGHT...AND WITH CURRENTLY
FORECAST HOURLY TEMPERATURES...PARTS OF THE AREA DO REACH WIND
CHILL ADVISORY CRITERIA FOR A COUPLE OF HOURS BEFORE RISING. WITH
A LITTLE UNCERTAINTY AS TO HOW LOW THE TEMPERATURES WILL DROP
BEFORE ONSET OF THE RISE...WE HAVE ELECTED TO HOLD OFF ON AN
ADVISORY FOR THE TIME BEING. WILL PASS ALONG CONCERN TO THE
EVENING SHIFT HOWEVER.
AFOREMENTIONED CLIPPER SYSTEM IS TAKING A MORE SOUTHWESTERLY TRACK
THAN PREVIOUS FORECASTS...SO WE HAVE REMOVED THE SNOW CHANCES FOR
THE FORECAST AREA FOR TOMORROW NIGHT AND WEDNESDAY...FAVORING A
SCATTERED FLURRY MENTION INSTEAD. TEMPERATURES TAKE ANOTHER TUMBLE
ON THE BACKSIDE OF THE TROUGH...WITH WELL BELOW ZERO LOWS FORECAST
FOR THURSDAY MORNING...AS ARCTIC HIGH SINKS THROUGH THE UPPER
MIDWEST. WOULD NOT BE SURPRISED TO SEE SOME 20 BELOW READINGS
ALONG THE I-90 CORRIDOR...WHERE THE FRESH SNOW HAS FALLEN AND THE
HIGH WILL BE IN CLOSEST PROXIMITY.
WE QUICKLY MAKE A RETURN TO WARMER AIR TOWARD THE WEEKEND...WITH
HIGHS ACTUALLY APPROACHING FREEZING FOR THE FIRST TIME SINCE THE
BEGINNING OF THE MONTH. PRECIPITATION CHANCES IN THE EXTENDED LOOK
TO INCREASE FOR FRIDAY...WITH WARM ADVECTION INCREASING...AND ALSO
FOR THE BEGINNING OF NEXT WEEK...WITH DEEP LOW PRESSURE SYSTEM SET
TO ORGANIZE AND PUSH THROUGH THE REGION ON SUNDAY NIGHT/MONDAY.
QUESTIONS WITH THIS REVOLVE AROUND PRECIP TYPE WITH MODEL
DISCREPANCIES ON EXACTLY WHERE THE WARM SECTOR WILL BE LOCATED.
&&
.PREV DISCUSSION...
/ISSUED 112 PM CST MON JAN 21 2008/
WE HAVE ADDED A FEW COUNTIES TO OUR SNOW ADVISORY AND EXTENDED THE
TIME OF A PORTION OF IT UNTIL 03Z. 25 TO 35 DBZ SNOW BAND HAS
DEVELOPED IN EXPECTED FRONTOGENETIC REGION ACROSS SOUTH CENTRAL
MINNESOTA...AND IS LIFTING...AS PROGGED...TO THE EAST NORTHEAST.
REPORTS FROM SOUTHEAST MINNESOTA INDICATE THAT...UNLIKE BENEATH
THE LIGHTER ECHOES...LARGE FLAKES /FINALLY AS EXPECTED/ ARE
FALLING AND ACCUMULATING QUITE RAPIDLY. A DECISION ON SOME OF THE
WISCONSIN COUNTIES WILL HAVE TO BE MADE FOR REGULAR PACKAGE
ISSUANCE TIME...WITH RUC/NAM FORECASTS TAKING THE FRONTOGENETIC
AREA VERY NEAR THE DURAND...ELLSWORTH...AND EAU CLAIRE VICINITIES.
&&
.AVIATION.../18Z TAF ISSUANCE/
SNOW CONTINUES ACROSS EAU...MSP...RWF...AND RNH TAF SITES IN
RESPONSE TO CONVEYOR BELT OF MOISTURE OVERIDING WARM FRONTAL
BOUNDARY ABOVE CENTRAL IOWA. SHORT DURATION VFR CIGS AND VSBYS
WILL BE ENCOUNTERED PRIOR TO 00Z AT THESE AIRPORTS. GFS40 ISENTROPIC
ANAL MUCH OF THE ACTIVITY WILL END BY 03Z TIME FRAME. 0.5 REFLECTIVELY
SIGNATURES INDICATING A DECREASING TREND OF INTENSITY ACROSS FAR
SOUTH CENTRAL MN. BEST FRONTOGENTIC FORCING AND DR DENDRITE TEMPERATURES
WILL ALSO BE SHOVED SOUTH BY THE EARLY EVENING HOURS...LIMITING ANY
APPRECIABLE SNOW AMOUNTS THEREAFTER. VSBYS WILL RETURN TO VFR MODE
BY 04Z ALL TAF SITES...WITH MVFR TO VFR CIGS BECOMING THE NORM ALL
LOCATIONS ALSO THIS TIME FRAME. ANOTHER FAST MOVING UPPER LEVEL
TROUGH WILL BRING A SHORT LIVED DECK OF MVFR CIGS TO ALL MN TAF
SITES BY 15Z ON TUE...AND ACROSS WEST CENTRAL WI BY 18Z.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...SNOW ADVISORY UNTIL 9 PM CST THIS EVENING FOR FREEBORN-GOODHUE-
     RICE-STEELE-WASECA.
     SNOW ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR FARIBAULT-MARTIN.
WI...NONE.
&&
$$
KAT/AJZ
</pre> mn
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
112 PM CST MON JAN 21 2008
.UPDATE...
UPDATED PUBLIC DISCUSSION.
&&
.DISCUSSION...
WE HAVE ADDED A FEW COUNTIES TO OUR SNOW ADVISORY AND EXTENDED THE
TIME OF A PORTION OF IT UNTIL 03Z. 25 TO 35 DBZ SNOW BAND HAS
DEVELOPED IN EXPECTED FRONTOGENETIC REGION ACROSS SOUTH CENTRAL
MINNESOTA...AND IS LIFTING...AS PROGGED...TO THE EAST NORTHEAST.
REPORTS FROM SOUTHEAST MINNESOTA INDICATE THAT...UNLIKE BENEATH
THE LIGHTER ECHOES...LARGE FLAKES /FINALLY AS EXPECTED/ ARE
FALLING AND ACCUMULATING QUITE RAPIDLY. A DECISION ON SOME OF THE
WISCONSIN COUNTIES WILL HAVE TO BE MADE FOR REGULAR PACKAGE
ISSUANCE TIME...WITH RUC/NAM FORECASTS TAKING THE FRONTOGENETIC
AREA VERY NEAR THE DURAND...ELLSWORTH...AND EAU CLAIRE VICINITIES.
&&
.AVIATION.../12Z TAF ISSUANCE/
LIGHT SNOW LOOKS TO MAKE IT TO ALL TAF SITES TODAY...WITH SOME
CHANCES OF IFR CONDITIONS AT RWF...MSP...AND WI TAF SITES. EARLY
LOOK AT 12Z MPX RAOB DATA SHOWS MOISTENING DOWN TO 3100 FT AS
ARCTIC MASS HAS RAPIDLY MOISTENED WITH PACIFIC MOISTURE FEEDING
INTO OUR ONCE VERY DRY AIR MASS. UPPER SUPPORT IS INCREASING AND
WIND PROFILERS FROM UPSTREAM /SRN TO CTRL PLAINS/ ARE SHOWING A
RESPONSE WITH A 65 KT MORNING LOW LEVEL JET IN THE SRN TO CTRL
PLAINS POINTED INTO IA AND SRN MN. SO EXPECT CIGS TO CONTINUE TO
LOWER THROUGH THE MORNING WITH SNOW EVENTUALLY MAKING IT DOWN. AS
SYSTEM TO OUR SOUTH SORT OF REDEFINES ITSELF...AREA BECOMES UNDER
MORE DEFORMATION THAN WARM AIR ADVECTION BY MID AFTN...NAMELY EAU.
SO KEEP SNOW PREDOMINANT AT MOST SITES FROM LATE MRNG THRU AFTN
AND FROM THE GET GO AT RWF. AS THE LOW MOVES INTO WI...A BAGGY LOW
LEVEL GRADIENT IS LEFT IN ITS PLACE THIS EVE AND EXPECT MVFR CIGS
TO BE WIDESPREAD...SLOWLY BEGINNING TO SCOOT DURING THE OVERNIGHT
AS A MORE PROGRESSIVE PATTERN SETS UP INTO MIDWEEK.
&&
.PREV DISCUSSION...
/ISSUED 543 AM CST MON JAN 21 2008/
THICKENING CLOUDS HAVE PRETTY MUCH STEADIED TEMPERATURES LAST FEW
HOURS WITH SLIGHT RISES IN SW MN WHERE WINDS HAVE GAINED A
SOUTHEAST COMPONENT. UPPER WINDS HAVE BACKED ENOUGH IN LAST 12 TO
24 HOURS AS TROUGH SLOWLY DIGS OUT WEST TO ALLOW SOME HIGHER LEVEL
MOISTURE TO MOVE INTO AREA. LIMITED MOISTURE HAS KEPT ANY SNOW
FROM ACCUMULATING THUS FAR...BUT VISIBILITY BEGINNING TO COME
DOWN IN SC MN INTO THE 3-5 MILE RANGE. BEST WARM ADVECTION ABOVE
850 MB AS SYSTEM COMES THRU. BY 12Z WAA AT 700 MB ACTUALLY QUITE
STRONG INTO S MN AS 700 MB WINDS INCREASE TO AROUND 30 KT
WITH WAA CONTINUING INTO THE EARLY AFTERNOON AROUND FRM AND THRU
THE AFTERNOON IN SE MN INTO THE EAU AREA. SWLY FLOW SHOULD
CONTINUE LONG ENOUGH TO CONTINUE MOISTENING AND EXPECT VISIBILITIES
TO BEGIN TO DROP AND SNOW TO BEGIN ACCUMULATING BETTER BY 12Z. THE
00Z OMA RAOB SHOWED .25 PWATS WHICH SHOULD BE WORKING INTO S MN.
SNOW RATIOS WILL BE HIGH IN THE 15 TO 20 TO ONE RANGE GIVEN THE
COLD AIRMASS. WILL CONTINUE WITH THE SNOW ADVISORY ACROSS OUR S
TIEROF COUNTIES FOR TODAY...BUT THINK AMOUNTS WILL BE A BIT LESS
THAN WE HAVE GOING NOW SINCE LITTLE ACCUM HAS OCCURRED IN THE
OVERNIGHT. METERS HAVE BEEN SHOWING -SN ACROSS MUCH OF SODAK WITH
VISBYS STEADILY DROPPING IN SODAK WITH -SN MOVING INTO W MN. THUS
MOVED THE MENTION OF -SN A BIT FARTHER N IN MN. TEMPERATURES WILL
BE TRICKY NEXT COUPLE DAYS WITH PUSH/PULL PATTERN AS A COUPLE WEAK
SYSTEMS COME THRU WITH WIND SHIFTS AND CLOUDS. A WINDOW OF
OPPORTUNITY FOR TEMPS TO DROP TONIGHT AS SURFACE RIDGE MOVES
ACROSS AREA...BUT LATE TONIGHT WEST WINDS INCREASE AHEAD OF
UPSTREAM COLD FRONT. MAY SEE SOME FLURRIES WITH FRONTAL PASSAGE
MAINLY IN CENTRAL MN INTO WI. GFS AND CANADIAN MODEL QUITE SIMILAR
ON WEAK CLIPPER MOVING THRU LATE TUES NIGHT/EARLY WED WITH LOW
TRACKING ACROSS SODAK INTO E NEBRASKA WHICH WOULD KEEP SNOW
CHANCES MAINLY SW OF OUR AREA. STILL LOOKING LIKE A SIGNIFICANT
WARMING TREND BRINGING US BACK TO AT LEAST NORMAL TEMPERATURES
LATE IN THE WEEK.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...SNOW ADVISORY UNTIL 9 PM CST THIS EVENING FOR FREEBORN-GOODHUE-
     RICE-STEELE-WASECA.
     SNOW ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR FARIBAULT-MARTIN.
WI...NONE.
&&
$$
KAT/MTF/BAP
</pre> mn
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
300 PM CST MON JAN 21 2008
.SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT...HIGH PRESSURE CENTERED
OVER THE MID ATLANTIC SEABOARD THIS AFTERNOON WAS STILL DOMINATING
OVER OUR CWA AND PROVIDING MOSTLY SUNNY SKIES OVER THE EASTERN TWO
THIRDS OF OUR CWFA THIS AFTERNOON. TEMPERATURES HAVE REBOUNDED
NICELY AFTER A RATHER COLD START AND RISEN INTO THE UPPER 40S AND
LOWER 50S. THE SURFACE HIGH WILL CONTINUE TO SHIFT EAST TONIGHT INTO
THE ATLANTIC AND ALLOW FOR WEATHER CHANGES FROM THE WEST. WATER
VAPOR IMAGERY/RUC ANALYSIS SHOWS A SHORT WAVE OVER COLORADO THAT
WILL MOVE EAST TONIGHT AS WELL. AS IT DOES...A SURFACE LOW OVER
NORTHWEST NEW MEXICO WILL DEEPEN AND MOVE OFF TO THE NORTHEAST. THIS
LOW WILL SEND A TRAILING COLD FRONT THROUGH OUR CWFA TUESDAY. WAA
WILL BEGIN INCREASING FROM THE WEST TONIGHT AND BRING US INCREASING
RAIN CHANCES. REGIONAL RADARS SHOW LIGHT RAIN ALONG THE INTERSTATE
20 CORRIDOR IN NORTHERN LOUISIANA THAT WILL SHIFT INTO OUR PARISHES
THIS EVENING. WHILE THIS IS OCCURRING OUR EASTERN SITES WILL BEGIN
TO RAPIDLY COOL. OVERNIGHT LOWS WILL LIKELY OCCUR AT MIDNIGHT AND
REMAIN STEADY OR WARM SLIGHTLY AFTER MIDNIGHT. ALL SITES ARE
EXPECTED TO REMAIN ABOVE FREEZING AT THE SURFACE BUT FORECAST
SOUNDINGS STILL SHOW SOME POTENTIAL FOR LIGHT SLEET MIXED WITH RAIN
AT THE ONSET OF RAIN IN OUR NORTHEAST AND EAST COUNTIES. ANY MIXED
PRECIPITATION THAT OCCURS SHOULD BE VERY BRIEF AS THE ATMOSPHERE
SHOULD WARM RESULTING IN ALL RAIN. THE COLD FRONT IS EXPECTED TO BE
ENTERING OUR DELTA COUNTIES BY SUNRISE TUESDAY MORNING AND BE JUST
NORTHWEST OF JACKSON BY NOON AND NEAR HATTIESBURG BY SUNSET. THE
RAIN SHOULD BE WIDESPREAD TUESDAY OVER MUCH OF OUR AREA...BUT MUCH
OF THE RAINFALL WILL BE LIGHT AS PWS ARE ONLY EXPECTED TO POOL NEAR
AN INCH AHEAD OF THE FRONT. MODELS ARE STILL INDICATING SOME
ELEVATED INSTABILITY AROUND NOON AS THE FRONT MOVES INTO CENTRAL
MISSISSIPPI. WL MENTION THUNDER TUESDAY GENERALLY ALONG AND SOUTH OF
INTERSTATE 20. THE GFS PROLONGS RAIN TUESDAY NIGHT IN OUR SOUTH DUE
TO A WEAK SHORTWAVE MOVING OVER THE AREA BUT HIGH PRESSURE BEHIND
THE FRONT WILL BE BUILDING INTO THE AREA AND SHOULD PUSH THE FRONT
FAR ENOUGH SOUTH TO END RAIN CHANCES SHORTLY AFTER MIDNIGHT.
WEDNESDAY MORNING LOWS WILL BE BACK DOWN TO FREEZING IN THE NORTH
AND RANGE TO THE LOWER 40S IN THE SOUTH. /22/
.LONG TERM...WEDNESDAY THROUGH MONDAY...MADE A FEW CHANGES TO THE
PREVIOUS LONG TERM THIS AFTERNOON. STRONG COLD FRONT WILL MOVE
THROUGH THE AREA TUESDAY NIGHT AND HIGH PRESSURE WILL FIRMLY HAVE A
GRIP ON THE ARKLAMISS BY WEDNESDAY AFTERNOON. A REINFORCING SHOT OF
COLD AIR WILL PUSH ACROSS THE AREA WEDNESDAY NIGHT INTO THURSDAY.
STUCK NEAR GUIDANCE FOR OVERNIGHT LOWS THURSDAY...BUT DID CUT WELL
BELOW GUIDANCE FOR HIGHS ON THURSDAY. BOTH THE EURO AND THE GFS
INDICATE COLD H925 WITH THE GFS BEING COLDER RANGING FROM -10 TO -3C
ACROSS THE AREA. THE EURO IS A LITTLE WARMER...BUT THIS WILL STILL
EQUATE TO A COLD DAY ON THURSDAY WITH HIGHS GENERALLY IN THE UPPER
30S TO NEAR 40.
HIGH PRESSURE WILL PREVAIL OVER THE AREA INTO FRIDAY...BUT THE HIGH
OVER THE EAST COAST WILL BEGIN TO SHIFT TO THE SOUTH AND A MOIST
SOUTHEASTERLY FLOW WILL BEGIN FRIDAY AFTERNOON. BOTH THE GFS/EURO
PUSH MID LEVEL SHORT WAVES ACROSS THE AREA SATURDAY AND SUNDAY AND
THIS COMBINED WITH THE MOIST FLOW SHOULD KICK OF SOME SHOWER THROUGH
THE WEEKEND. THE LATEST RUN OF THE GFS KEEP THE RIDGE TO THE
SOUTHEAST AND KEEPS US IN SOUTHERLY FLOW INTO TUESDAY WITH A POTENT
SYSTEM MOVING THROUGH THE AREA LATE TUESDAY. THE EURO MOVES DEEPER
SHORT WAVES ACROSS THE AREA...ONE ON SATURDAY AND A MORE SIGNIFICANT
ONE LATE ON TUESDAY. WITH ALL OF THIS SAID PRETTY MUCH JUST WENT
WITH GUIDANCE FOR POPS...BUT DID RAISE AFTERNOON HIGHS ABOVE
GUIDANCE SATURDAY THROUGH MONDAY AS THE GFS/EURO INDICATE VERY
H850/H925 TEMPS. STUCK WITH THE PREVIOUS LONG TERM FORECAST UNLESS
OTHERWISE MENTIONED ABOVE SO WILL ATTACH THE PREVIOUS LONG TERM
DISCUSSION./15/
PREVIOUS LONG TERM...WEDNESDAY THROUGH MONDAY. DID NOT MAKE ANY REAL
CHANGES TO THE FORECAST AT THIS TIME. LOOKS LIKE THE WEATHER WILL BE
QUIET FOR THE MOST PART...BUT THERE MAY BE A FEW COLD DAYS BEFORE
THE NEXT CHANCE OF RAIN BY THE END OF THE WEEK. TWEAKED TEMPERATURES
IN A FEW SPOTS...OVERALL GUIDANCE WAS GOOD.
A COLD AIRMASS SETTLES OVER THE AREA BY THURSDAY...BRINGING ANOTHER
SHOT OF ARCTIC AIR. LOW TEMPERATURES WILL BE BACK IN THE LOWER AND
MID 20S FOR MUCH OF THE AREA BY WEDNESDAY NIGHT...WITH VALUES A FEW
DEGREES COOLER BY THURSDAY NIGHT. HIGHS MAY NOT GET OUT OF THE
40S...BOTH WEDNESDAY AND THURSDAY. THE HIGH SHIFTS EAST BY FRIDAY
AFTERNOON. CIRCULATION AROUND THE HIGH BRINGS IN SOME MOIST AND WARM
AIR FROM THE GULF. FLOW ALOFT WAS ZONAL FOR MOST OF THE
WEEK...HOWEVER A SHORT WAVE SWINGS THROUGH AROUND THURSDAY AND THE
RIDGE BUILDS INTO THE PLAINS BY FRIDAY. THE UPPER RIDGE SHIFTS EAST
AND FLATTENS BY FRIDAY. THE UPPER JET WAS BRINGING PLENTY OF PACIFIC
MOISTURE INTO THE SOUTHWEST US. THE MODEL SHOWS A POTENT UPPER LOW
SCALING THE WEST COAST BEFORE MOVING INLAND AROUND SATURDAY. A WARM
FRONT SEEMS TO DEVELOP ACROSS THE SOUTHERN STATES AROUND SATURDAY.
ALTHOUGH...MODELS DO NOT SHOW MUCH INSTABILITY...BUT SUSPECT IT WILL
INCREASE THROUGH THE PERIOD. ANYWAY...MAINTAINED THUNDER FOR
SATURDAY...MAY HAVE TO ADD THUNDER FOR THE FRIDAY NIGHT PERIOD.
OVERALL THE EXTENDED FORECAST WAS GOOD. /07/
&&
.AVIATION...CLOUDS AND RAIN WILL INCREASE FROM THE WEST TONIGHT
ALTHOUGH...VFR CONDITIONS CAN BE EXPECTED THROUGH 06Z TUESDAY.
CEILINGS
WILL GRADUALLY LOWER FROM THE WEST AFTER MIDNIGHT. MVFR CEILINGS CAN
BE EXPECTED IN THE WEST BY 08Z GRADUALLY DECREASING TO IFR BY 12Z
TUESDAY. SOME LIFR CEILINGS CAN ALSO BE EXPECTED. THUNDERSTORMS WILL
BE POSSIBLE OVER THE CENTRAL AND SOUTHERN PORTIONS OF THE AREA BY
18Z AND CONTINUE THROUGH 23Z.  /22/
&&
.PRELIMINARY POINT TEMPS/POPS...
JACKSON       39  53  36  50 /  41  60  13   6
MERIDIAN      34  53  36  51 /  28  59  14   6
VICKSBURG     42  53  37  47 /  51  61  13   6
HATTIESBURG   38  60  41  52 /  16  54  17   9
NATCHEZ       44  59  39  51 /  36  51  35   8
GREENVILLE    38  45  32  47 /  78  76   7   6
GREENWOOD     38  46  32  48 /  69  77   7   6
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
SHORT TERM/AVIATION: 22
LONG TERM:15/07
</pre> ms
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
1212 PM CST MON JAN 21 2008
...UPDATE TO PUBLIC AND AVIATION DISCUSSIONS...
.UPDATE...
HAVE STARTED RECEIVING GROUND TRUTH TO RADAR RETURNS OVER THE PAST
COUPLE OF HOURS ROUGHLY SOUTH OF HIGHWAY 60 AND WEST OF HIGHWAY
65. MOST OF THE REPORTS CONSISTED OF VERY LIGHT SNOW OR SLEET...OR
A COMBINATION OF THE TWO. THE RADAR ECHOES AND REPORTS HAVE
COINCIDED FAIRLY WELL WITH SOME COOLER CLOUD TOPS...COLDER THAN
-15C...AS DEPICTED ON IR IMAGERY. LIKELY GETTING AT LEAST SOME ICE
CRYSTALS IN THE CLOUDS IN THESE AREAS...THUS AIDING THE
PRECIPITATION PROCESS. MODELS ARE HANDLING THIS MID LEVEL MOISTURE
RATHER POORLY...WITH THE EXCEPTION OF THE RUC13. HAVE FOLLOWED
THIS MODEL CLOSELY FOR THE REMAINDER OF TODAY. EXPECT THE LIGHT
SHOWERY TYPE FROZEN PRECIPITATION TO CONTINUE AS WEAK SLUGS OF
ISENTROPIC UPGLIDE SHIFT THROUGH THE AREA. ACCUMULATIONS WILL BE
VERY MINOR. MADE UPDATES TO POP AND WEATHER GRIDS TO ACCOUNT FOR
ABOVE THINKING. HAVE ALSO LOWERED TEMPERATURES OVER MANY
AREAS...ESPECIALLY THOSE THAT SAW A QUICK INCREASE IN CLOUDS JUST
AFTER SUNRISE. HOURLY AND FIRE WEATHER GRIDS HAVE ALSO BEEN
TWEAKED. UPDATED PUBLIC AND FIRE WEATHER FORECASTS ALREADY SENT.
SCHAUMANN
&&
.DISCUSSION...
MODELS REMAIN IN GOOD AGREEMENT SO THE IMPACT OF FREEZING RAIN /
DRIZZLE ON ROADWAYS TONIGHT REMAINS MAIN FORECAST CONCERN.
SHORT TERM...TODAY THROUGH TUESDAY
GULF STRATUS NEARING THE RED RIVER WILL CONTINUE TO MAKE GOOD
NORTHWARD PROGRESS ON 50+ KNOT LLVL JET. BASED UPON GFS
SOUNDINGS...HAVE MAINTAINED LOW POPS FOR LIGHT RAIN OVER SE KS AND
WRN MO THIS AFTERNOON BUT DELAYED POPS UNTIL TONIGHT OVER THE REST
OF THE REGION.
SOUNDINGS CONTINUE TO SHOW LIMITED DEPTH OF SATURATED
COLUMN TO GENERALLY BETWEEN H9-H75 OVER THE WESTERN HALF OF THE
CWA...WITH THE DRYING BELOW H9 EXPECTED TO LIMIT THE AMOUNT OF LIGHT
FREEZING PCPN FROM HIGHWAY 65 WESTWARD INTO SE KS. AS FRONT NEARS
THIS EVENING...VEERING WINDS TO ENHANCE CONVERGENCE SATURATING
COLUMN TO GREATER DEPTH INCLUDING THE BOUNDARY LAYER PRIMARILY EAST
OF HIGHWAY 65. TIMING / LENGTH OF PCPN AGAINST THE ARRIVAL OF SUB
FREEZING TEMPERATURES EXPECTED TO RESULT IN ONLY A GLAZE OF ICING
OVER MOST AREAS...THOUGH AREAS SOUTH OF I-44 WILL NEED TO BE
MONITORED CLOSELY.
SUBSIDENCE / DRYING ON TUESDAY TO END ANY REMAINING FREEZING
DRIZZLE OR LIGHT SNOW FROM WEST TO EAST DURING THE MORNING.
LONG TERM...WEDNESDAY INTO THE WEEKEND
SECOND NORTHERN STREAM CLIPPER TO BRING A REINFORCING SHOT OF
COLD AIR AND POSSIBLY A FEW FLURRIES TO CENTRAL MO WEDNESDAY.
00Z ECMWF TRENDING QUICKER IN KICKING ENERGY OUT OF WRN
TROF...POSSIBLY LEADING TO ANOTHER LIGHT PRECIPITATION EVENT ON
FRIDAY INTO THE WEEKEND.
&&
.AVIATION...
FOR THE 18Z TAF CYCLE...CEILINGS ACROSS SOUTHEAST KANSAS AND
NORTHEAST OKLAHOMA ARE BEGINNING TO SLIP INTO THE MVFR CATEGORY.
EXPECT THESE MVFR CEILINGS TO SPREAD INTO SOUTHWEST MISSOURI
AROUND MID AFTERNOON. WILL ALSO SEE SHOWERS OF LIGHT SLEET
CONTINUE ACROSS THE AREA THROUGH ABOUT ABOUT 22Z. CEILINGS WILL
CONTINUE TO LOWER TONIGHT...LIKELY REACHING THE IFR CATEGORY
BETWEEN 06Z AND 08Z. MAY EVEN SEE CEILINGS APPROACH THE LIFR
CATEGORY LATE TONIGHT...ALONG WITH MVFR VISIBILITIES. LIGHT FROZEN
PRECIPITATION IS ALSO EXPECTED UNTIL THE LATE OVERNIGHT HOURS.
LIGHT FREEZING RAIN...LIGHT SNOW...LIGHT SLEET AND FREEZING
DRIZZLE WILL ALL BE POSSIBLE. CEILINGS AND VISIBILITIES WILL
SLOWLY IMPROVE FROM MID TO LATE MORNING ON TUESDAY. WINDS WILL
REMAIN BRISK OUT OF THE SOUTH INTO EARLY THIS EVENING BEFORE
SHIFTING TO THE NORTHWEST BEHIND A COLD FRONT. CONSIDERED WIND
SHEAR GROUP WITH VEERING WINDS THIS EVENING AND WITH COLD FRONTAL
PASSAGE LATER THIS EVENING. KEPT IT OUT FOR NOW BUT WILL CONTINUE
TO MONITOR.
SCHAUMANN
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
</pre> mo