FXAK68 PAFC 052131
AFDAFC

AREA FORECAST DISCUSSION 
SOUTHCENTRAL AND SOUTHWEST ALASKA
1230 PM AKST SAT DEC 5 2009

.ANALYSIS AND UPPER LEVELS...HIGH AMPLITUDE PATTERN REMAINS IN 
PLACE WITH STRONG BLOCKING RIDGE EXTENDING FROM NORTHEAST PACIFIC 
TO EASTERN MAINLAND ALASKA AND A TROUGH FROM EASTERN RUSSIA 
SOUTHWARD ACROSS THE BERING AND NORTH PACIFIC TO ABOUT 30N LATITUDE. 

ONE STORM FORCE LOW NORTH OF THE WESTERN ALEUTIANS IS SLOWLY 
EXITING OFF TO THE NORTHWEST...AND WINDS HAVE BEGUN TO DIMINISH
ACROSS THE REGION. THE BENT BACK OCCLUSION IS STILL IMPACTING THE 
FAR WESTERN ALEUTIANS WITH 55 KT WINDS AND BLIZZARD CONDITIONS. THE
WEAKENING OCCLUSION WRAPS ALL THE WAY ACROSS THE NORTHERN BERING 
THEN SOUTHEASTWARD ACROSS THE SOUTHWEST ALASKA COAST TO JUST SOUTH 
OF KODIAK ISLAND. ALTHOUGH THIS FRONT IS WEAKER THAN IT WAS IT IS 
STILL PACKING A PUNCH OVER SOUTHWEST ALASKA...WITH 40 TO 65 KT OF
WIND IN THE BRISTOL BAY REGION AND MODERATE TO HEAVY PRECIPITATION
FROM KODIAK ISLAND TO THE SOUTHWEST COAST. ANOTHER HURRICANE FORCE
STORM OVER THE NORTH PACIFIC IS GEARING UP TO TAKE A SIMILAR TRACK 
TO THIS PAST STORM.

SOUTHCENTRAL ALASKA IS SHROUDED IN HIGH CLOUDS...BUT OTHERWISE
EXPERIENCING A VERY CALM DAY UNDER THE INFLUENCE OF THE RIDGE. 

.MODEL DISCUSSION...MODELS ARE IN VERY GOOD AGREEMENT THROUGH 
TUESDAY AND FORECAST CONFIDENCE IS HIGH.

.SHORT TERM FORECAST...

SOUTHERN MAINLAND ALASKA...AS THE CURRENT BERING LOW EXITS TOWARD
EASTERN RUSSIA THE UPPER RIDGE WILL BUILD WESTWARD BEHIND
IT...HELPING TO SHOVE THE REMNANTS OF THE OCCLUSION BACK INTO THE
BERING...HELPING TO GRADUALLY DRY OUT KODIAK ISLAND AND SOUTHWEST
ALASKA LATE TONIGHT THROUGH SUNDAY AFTERNOON. WINDS WILL REMAIN VERY
STRONG ALONG THE ALASKA PENINSULA AND SOUTHWEST ALASKA COAST THROUGH
MONDAY ON THE PERIPHERY OF THE NEXT BERING STORM. MEANWHILE...AN
ARCTIC LOW OVER THE POLE WILL BEGIN TO DROP DOWN THE EAST SIDE OF 
THE RIDGE INTO CANADA WHICH WILL HELP THE RIDGE TO RETROGRADE NORTH 
AND WEST...BECOMING ANCHORED DIRECTLY OVER THE MIDDLE OF MAINLAND 
ALASKA MONDAY NIGHT. THUS...BENIGN WEATHER WILL PERSIST.

BERING SEA/ALEUTIANS...THE IMPACT OF THIS STORM WILL BE SIMILAR 
TO THE LAST...ALTHOUGH THE WINDS WILL NOT BE QUITE AS STRONG DUE 
TO THE FACT THAT THIS STORM ALREADY NEAR ITS MAXIMUM STRENGTH AND
WILL GRADUALLY WEAKEN AS IT TRACKS TO THE BERING SEA MONDAY. THE 
HIGH WIND WATCH WILL BE UPGRADED TO A WARNING FOR THE SOUTHERN 
ALASKA PENINSULA. EVERYWHERE ELSE IS EXPECTED TO REMAIN BELOW 
WARNING CRITERIA...THOUGH WINDS WILL STILL REACH A RESPECTABLE 
45 TO 55 KT ACROSS THE EASTERN BERING AND ALEUTIANS. WITH ANOTHER
SURGE OF WARM "TROPICAL-LIKE" AIR PRECIPITATION WILL FALL MAINLY 
AS RAIN. THE ONE EXCEPTION TO THIS IS THE FAR WESTERN ALEUTIANS 
WHICH WILL REMAIN ON THE COLD SIDE OF THE STORM AND WILL LIKELY 
SEE ANOTHER ROUND OF SNOW AND BLOWING SNOW. AT THIS POINT IT LOOKS
LIKE THE OCCLUSION WILL STAY NORTH OF THE WESTERN ALEUTIANS AND 
THE SNOW WILL NOT BE AS STEADY AS THE CURRENT STORM...HOWEVER IF 
THIS CHANGES THEN ANOTHER BLIZZARD IS LIKELY.

.LONG TERM FORECAST...THE BLOCKING RIDGE LOOKS LIKE IT WILL HOLD
THROUGH THE END OF NEXT WEEK...SO EXPECT A CONTINUATION OF THE
CURRENT PATTERN. THE ONE NOTABLE DIFFERENCE IS THAT THE UPPER JET
WILL HELP DIG THE UPPER TROUGH EASTWARD TOWARD THE NORTHEAST
PACIFIC...HELPING TO BEGIN TO CUT-OFF THE RIDGE AT ITS BASE. SO
INSTEAD OF THE SUBTROPICAL JET CURVING NORTHWARD TOWARD THE EASTERN
BERING...IT WILL CONTINUE EASTWARD ACROSS THE PACIFIC. WITH A MORE
ZONAL JET WELL TO THE SOUTH...STORMS AFFECTING THE BERING SEA AND
ALEUTIANS WILL BE MUCH WEAKER THAN THE CURRENT TWO.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 191.
         HIGH WIND WARNING 181. 
         HIGH SURF ADVISORY 171.
MARINE...STORM WARNING...150 155 160 165 170 172 179 180.
         GALE WARNING...130 132 138 140 171 175 176 185.
FIRE WEATHER...NONE.

SEB DEC 09