FXUS63 KEAX 210602
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 
100 AM CDT SAT AUG 21 2004

.DISCUSSION...

EARLY MORNING SATELLITE IMAGERY AND UPPER AIR ANALYSIS SHOW 
UNSEASONABLY STRONG UPPER LOW OVER HUDSON BAY WITH MEAN TROUGH 
EXTENDING SOUTHWARD ACROSS GREAT LAKES INTO MID MS VALLEY AND OZARKS 
REGION. 04Z SUBJECTIVE SURFACE ANALYSIS INDICATES COLD FRONT 
EXTENDING ACROSS OH VALLEY BACK INTO EASTERN TX SUPPRESSING GULF 
MOISTURE SOUTH OF REGION...WHILE SECONDARY COLD FRONT ACROSS 
SOUTHERN IA INTO CENTRAL NE MARKS THE LEADING EDGE OF UNSEASONABLY 
COOL AND DRY AIR...WITH DEW POINTS IN EASTERN SD/WESTERN MN IN THE 
30S. AHEAD OF THIS FRONT LIGHT WINDS COMBINED WITH A MOIST GROUND 
FROM THURSDAY NIGHT'S RAINFALL WILL ALLOW FAVORABLE SETUP FOR DENSE 
FOG OVERNIGHT ACROSS SOUTHERN TWO THIRDS OF CWA. WILL LIKELY ISSUE 
DENSE FOG ADVISORY FOR AREAS ALONG/SOUTH OF HIGHWAY 36 THROUGH MID 
MORNING. 

MEANWHILE FURTHER WEST STRONG BELT OF WESTERLIES HAS UNDERCUT 
WESTERN RIDGE...RESULTING IN DEVELOPMENT OF REX BLOCK ACROSS AK/GULF 
OF AK...AND FALLING HEIGHTS ACROSS PACIFIC NORTHWEST. THIS IS THE 
ONSET OF A LONGWAVE PATTERN CHANGE WHICH WILL ALLOW SUMMER-LIKE 
WEATHER TO RETURN TO THE REGION EARLY NEXT WEEK...AS SOUTHWESTERLY 
FLOW DEVELOPS ACROSS THE CENTRAL CONUS. GOING FORECAST HANDLES 
WARM-UP WELL...WITH TEMPERATURES RETURNING TO NEAR 90 ACROSS 
PORTIONS OF THE CWA BY MONDAY...WITH DEW POINTS LIKELY RISING BACK 
INTO THE 70S. AS THIS WARMER AIR RETURNS TO THE REGION...MAY SEE A 
CHANCE OF ELEVATED SHOWERS/THUNDERSTORMS LATE SUNDAY NIGHT/EARLY 
MONDAY MORNING. ETA INDICATES DECENT PRESSURE ADVECTION ALONG 310K 
SURFACE ACROSS NORTHERN CWA ALONG WITH AREA OF ELEVATED INSTABILITY 
AHEAD OF WEAK SHORTWAVE DEPICTED BY BOTH ETA AND GFS. FOR NOW HAVE 
INCLUDED SLIGHT CHANCE POPS FOR THIS TIME PERIOD. 

SEAMAN

&&

.PREV DISCUSSION...

THE MID AFTERNOON SURFACE ANALYSIS DEPICTS TWO DISTINCT COLD FRONTS 
OVER THE CENTRAL UNITED STATES. THE FIRST IS PUSHING THROUGH 
SOUTHERN MISSOURI AND IS ASSOCIATED WITH THE WAVE THAT BROUGHT 
WIDESPREAD SHOWERS AND THUNDERSTORMS TO THE REGION LAST NIGHT.  THE 
SECOND COLD FRONT IS MAKING ITS WAY INTO NORTHERN IOWA, AND IS 
REMARKABLY CHILLY FOR THIS TIME OF YEAR. TEMPERATURES BEHIND THE 
FRONT IN NORTHERN MINNESOTA ARE ONLY 60 DEGREES WITH FULL SUNSHINE! 
THIS SUMMER CONTINUES TO BE ONE OF THE COOLEST IN MANY YEARS FOR THE 
CENTRAL UNITED STATES.

THE PATTERN IS BREAKING HOWEVER, AND A THERE IS CLEAR EVIDENCE OF 
THIS ON WATER VAPOR IMAGERY TODAY. THE WEST COAST RIDGE THAT HAS 
BEEN PERSISTENT NEARLY ALL SUMMER HAS BEEN SQUEEZED OFF. UNUSUALLY 
STRONG WESTERLIES OVER THE NORTHERN PACIFIC BASHED THE NORTHERN 
PERIPHERY OF THE HOT RIDGE DOWN THIS MORNING, AND THIS WILL FORCE 
THE UPPER LOW OVER CENTRAL CANADA TO MOVE EAST THIS WEEKEND. SO 
DESPITE THE VERY COLD AIRMASS OVER THE NORTHERN PLAINS THIS 
AFTERNOON, THE RAPID PROGRESSION OF THE POLAR VORTEX EAST THIS 
WEEKEND WILL ONLY PROVIDE MISSOURI WITH A GLANCING BRUSH WITH THE 
COLD AIR.

BEFORE THE BIG WARM UP EARLY NEXT WEEK, SURFACE HIGH PRESSURE WILL 
BRING VERY PLEASANT CONDITIONS TO THE REGION TOMORROW. PER MY 
EARLIER DISCUSSION SHALLOW GROUND FOG IS LIKELY TONIGHT. THE 
SHORTWAVE RESPONSIBLE FOR THE CLOUD COVER THIS AFTERNOON IS 
PROGRESSING TO THE EAST, AND SKIES SHOULD CLEAR OUT EARLY THIS 
EVENING OVER NORTHERN MISSOURI. WEAK LOW LEVEL FLOW, MOIST GROUND 
FROM LAST NIGHT'S RAIN, AND GOOD RADIATIONAL COOLING POINT TOWARD 
SOME LOCALLY DENSE FOG IN FAVORED AREAS. CLOUD COVER THIS AFTERNOON 
HAS KEPT THE MAJORITY OF MISSOURI COOL AND MOIST TODAY, SO 
SATURATION CAN BE EXPECTED EARLY TONIGHT.

AFTER THE FOG BURNS OFF TOMORROW MORNING, QUIET CONDITIONS ARE 
EXPECTED THROUGH THE REST OF THE WEEKEND. ZONAL FLOW ACROSS THE 
ROCKIES WILL INDUCE LEE SIDE TROUGHING OVER THE HIGH PLAINS AND 
SOUTHERLY WINDS WILL BRING HIGHER DEWPOINTS BACK TO THE REGION ON 
SUNDAY. THEY MAY REACH 70 DEGREES BY SUNDAY AFTERNOON SINCE LOW 
LEVEL MOISTURE HAS BUILT UP OVER TEXAS AND LOUISIANAN DURING THE 
LAST COUPLE OF DAYS. THIS AIRMASS IS HEADED OUR WAY. NEXT WEEK WILL 
PROBABLY FEEL LIKE SUMMER, AND SINCE THE LONGWAVE PATTERN HAS BROKEN 
IT MAY STICK AROUND FOR A WHILE.

KOCH

THE MEDIUM RANGE MODELS HAVE BEGUN TO CONVERGE TOWARD A SOLUTION FOR 
NEXT WEEK...WITH THE 00Z GFS COMING MORE IN LINE WITH THE ECMWF AND 
ENSEMBLE MEAN. THE ANTICIPATED PATTERN CHANGE WITH AN UPPER TROUGH 
ENTERING THE NORTHWEST CONUS WHILE THE RIDGE SLIDES EAST...WILL 
PLACE THIS REGION UNDER SOUTHWEST FLOW ALOFT. A PREDOMINANT 
SOUTHERLY FLOW AT THE SURFACE WILL ALLOW FOR AN INCREASE IN 
TEMPERATURES AND MOISTURE FOR NEXT WEEK. WITH A BIT MORE CONFIDENCE 
IN THE MODEL SOLUTIONS...ALBEIT STILL RATHER LOW...HAVE TRIED TO 
NARROW DOWN PRECIPITATION CHANCES. A SHORTWAVE IS FORECAST TO MOVE 
ACROSS THE CENTRAL PLAINS ON MONDAY. HAVE RETAINED SLIGHT 
PRECIPITATION CHANCES ACROSS EAST CENTRAL KANSAS AND CENTRAL 
MISSOURI WHERE MORE FAVORABLE FORCING AND MOISTURE WILL BE. A 
SURFACE FRONT IS EXPECTED TO STALL FROM MINNESOTA INTO WESTERN 
KANSAS THE MIDDLE OF NEXT WEEK. A PORTION OF THE UPPER TROUGH IS TO 
ADVANCE EAST AND DISLODGE THE FRONT TOWARD THE FORECAST AREA ON 
FRIDAY...WITH PRECIPITATION CHANCES INCREASING ACCORDINGLY.

STOFLET

&&

.PREV DISCUSSION...

1130 AM...
TEMPERATURES HAVE GONE NO WHERE THIS MORNING AND THICK CLOUD COVER 
WILL PLAGUE MISSOURI AND EASTERN KANSAS FOR MUCH OF THE DAY SOUTH OF 
INTERSTATE 70. I HAVE LOWERED TEMPERATURES FOR MUCH OF THE REGION. 
SEDALIA, CLINTON, WARRENSBURG, AND SEDALIA WILL STRUGGLE TO REACH 70.

FOG STILL LOOKS LIKE A GOOD BET TONIGHT. DEWPOINTS WILL NOT DROP 
MUCH TODAY GIVEN THE VERY WEAK LOW LEVEL FLOW.  CLOUD TRENDS WILL BE 
MONITORED THIS AFTERNOON AND EVENING, BUT I EXPECT A GRADUAL 
CLEARING FROM NORTH TO SOUTH. MODEL SOUNDINGS SUGGEST DRY AIR ABOVE 
A SHALLOW MOIST LAYER WHICH IS AN IDEAL SET UP FOR RADIATION FOG. 
THERE IS ALMOST NO FLOW FORECAST IN THE LOWEST 150MB EITHER, SO 
MIXING SHOULD NOT BE A PROBLEM. I'VE UPDATED THE GRIDS ACCORDINGLY, 
AND ALL BUT EXTREME NORTHERN MISSOURI MAY BE DEALING WITH DENSE FOG 
TOMORROW MORNING. (SLIGHTLY LOWER DEWPOINTS ARE EXPECTED ALONG THE 
IOWA BORDER TONIGHT.)

KOCH

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.

$$

WFO EAX