FXAK67 PAJK 111428
AFDAJK
SOUTHEAST ALASKA FORECAST DISCUSSION
630 AM ADT SAT AUG 11 2007
 
.SYNOPSIS... 
.SHORT RANGE...HIGH PRESSURE BUILDING IN SFC/ALF FROM THE NW.
WEAK SFC LOW MOVED SOUTH DOWN THE COAST OVERNIGHT AND IS NOW JUST
SOUTH OF CAPE ST JAMES. STILL PLENTY OF CLOUD COVER AND PATCHY
FOG OVER SE AK THIS MORNING...DENSE FOG ADVISORY ISSUED AT 6 AM
FOR ANGOON AREA...VALID TIL 8 AM...WHERE OBS AND WEB CAM IMAGES
SHOW VSBY LESS THAN 1/4 MILE. WILL ALSO UPDATE COASTAL MARINE
ZONE 52...ICY CAPE TO CAPE SUCKLING...TO HAVE A BIT STRONGER WEST
WINDS. CRUISE SHIP OB FROM NEAR BUOY 82 AT 5 AM REPORTED WEST
WIND 20KTS. THIS LOOKS TO BE ASSOCIATED WITH SFC PRESSURES RISING
MORE RAPIDLY THAN EXPECTED OVER THE NE GULF.  

DECIDED TO FOLLOW GFS AND EURO MODEL SOLUTIONS TODAY. THIS IS
MAINLY BECAUSE NAM MODEL INSISTS ON FAR TOO MUCH PRECIP IN PLACES
IT IS NOT EVEN OCCURRING. POCKET OF COOL TEMPS ALOFT KEEPING AMS
UNSTABLE TODAY. LIFTED INDEX VALUES FROM 12Z UPPER AIR SOUNDINGS
AT YAKUTAT AND ANNETTE ARE BELOW ZERO. SHOWERS SHOULD POP UP
AGAIN TODAY ZONES 29 AND 28...POSSIBLY ZONE 27 AS WELL. THE JET
STREAM WAS IN A BETTER POSITION FRI TO GENERATE TSTMS THAN TODAY
BUT THEY ARE STILL NOT OUT OF THE QUESTION OVER SE CORNER OF
PAMHANDLE. IN CENTRAL AND NRN PANHANDLE...A HALF DAY SAT WITH
CLOUD COVER WILL INHIBIT ONSET OF CONVECTION. INCREASING
SUBSIDENCE FROM APPCHG RIDGE LATER TODAY WILL THEN HELP DISSIPATE
CLOUDS AND STABILIZE AMS OVER NORTHERN ZONES. THIS WILL ALLOW MAX
TEMPS TO WARM NICELY THIS AFTN. S PANHANDLE WILL BEGIN TO
STABLIZE SAT EVENING AND CLEAR OUT MORE LATE SAT NIGHT. TA       

.LONG RANGE...THE FORECASTING MODELS THIS MORNING ARE IN GOOD
AGREEMENT THROUGH TUE NIGHT BUT THEN THEY DIFFER SOME WITH THE
PLACEMENT OF AN UPPER LEVEL LOW OVER SOUTH CENTRAL AK WED. THE
MODELS CONTINUE TO DIVERGE SOME THROUGH THE END OF THE WEEK WITH
THE INTERACTION BETWEEN THE NORTHERN AND SOUTHERN STREAMS. SO
FORECAST CONFIDENCE REMAINS LOW FROM WED THROUGH THE END OF THE
WEEK. USED THE 11/00Z GFS40 FOR THE MOST PART THEN BLENDED WITH
THE 11/00Z ECMWF FROM WED THROUGH THE END OF THE WEEK.
 
THE DRY AND SUNNY CONDITIONS WILL PERSIST INTO TUE NIGHT WITH THE
MODERATE OMEGA BLOCK OVER THE STATE. THE UPPER HIGH OVER OVER
WESTERN AK WILL FLATTEN OUT AS THE UPPER LEVEL LOW OVER THE
BERING TRACKS EAST OVER THE Y-K DELTA TUE. THIS WILL INCREASE THE
ONSHORE FLOW OVER THE NORTHERN GULF TUE MAINLY OVER PAYA. THE
UPPER HIGH OVER THE GULF WILL PUSH A MARINE LAYER OVER THE
EASTERN GULF THROUGH EARLY NEXT WEEK. THE COASTAL AREA MAY SEE AN
INCREASE IN LOW CLOUDS ON MON AND TUE.
 
THE WINDS OVER THE SE AK WILL REMAIN ON THE WEAK SIDE AS THERE
WILL NOT BE THAT MUCH OF A PRESSURE GRADIENT. EXCEPT ON SUN
MORNING...THERE WILL BE NORTHERLY WINDS TO 20 KT OVER LYNN CANAL
AS A 1011MB SURFACE LOW OVER DIXON ENTRANCE WILL INCREASE THE
PRESSURE GRADIENT WITH A 1025MB HIGH OVER SW YUKON.
 
AS MENTIONED ABOVE THERE IS LOW FORECASTER CONFIDENCE FROM TUE
NIGHT THROUGH THE END OF THE WEEK BECAUSE THERE IS A FEW
DIFFERENT SOLUTION IN HOW THE UPPER LEVEL LOW OVER THE SOUTH
CENTRAL INTERACTS WITH THE SOUTHERN STREAM UPPER LOW IN THE NORTH
PACIFIC. FIRST OFF...THE GFS IS PLACING THE NORTHERN LOW FURTHER
SOUTH IN THE GULF AND THIS WOULD INCREASE THE CHANCE OF CLOUDS
AND PRECIP FOR PAYA EARLIER. THE ECMWF AND THE GFS ENSEMBLE MEAN
BOTH HAVE THIS FEATURE FURTHER NORTH NEAR PWS. DID LEAN TOWARDS
THE ECMWF PATTERN AND SLOWED DOWN THE PROGRESS OF A WEAKENING
FRONT MOVING ACROSS THE NORTHERN GULF AS THE UPPER LOW MOVES
EAST. THIS FRONT SHEARS APART BEFORE IT GETS TO PAYA BUT THERE
WILL BE A CHANCE OF RAIN TO THE WEST ON WED. THE NEW 06 GFS DID
SLOW DOWN THE FRONT AND IS LOOKING MORE LIKE THE ECMWF AND THE
ENSEMBLE.
 
FOR THURSDAY AND FRIDAY...THE NORTHERN LOW WILL FUJIWHARA WITH
THE SOUTHERN LOW. THE NORTHERN LOW WILL SPIN INTO THE SOUTH
CENTRAL GULF AS THE SOUTHERN LOW DRIFTS INTO B.C. IN DOING SO A
WARM FRONT INCREASE THE CLOUDS OVER THE PANHANDLE AND WILL
INCREASE THE CHANCE OF RAIN OVER THE SOUTHERN HALF THURSDAY
MORNING INTO FRIDAY. THE FAR NORTHERN AREAS WILL BE SPARED THE
RAIN WITH EAST TO SOUTHEAST FLOW ALOFT BUT THE NORTH CENTRAL
AREAS WILL SEE A SLIGHT CHANCE. ABJ
 
 
.AJK...WATCHES/WARNINGS/ADVISORIES 
PUBLIC...NONE
MARINE...NONE