Heavy Freezing Spray Warning 64, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 PM AKST TUE FEB 15 2011

.MODEL DISCUSSION...MODELS FROM THE 12Z RUN ARE DOING WELL THROUGH
FRIDAY ACROSS THE FORECAST AREA. AFTER THAT THERE IS STILL A RAPID
PLUNGE INTO UNCERTAINTY AS THE GFS AND ECMWF DRAMATICALLY DIVERGE.
THE DEPTH AND STRUCTURE OF A LONG WAVE TROUGH ENTERING THE REGION
THIS WEEKEND AS WELL AS A RIDGE EARLY NEXT WEEK MAKE THE LONGER TERM
FORECAST A CHALLENGE.

.ANALYSIS AND UPPER LEVELS...AN UPPER LEVEL RIDGE OVER THE MAINLAND
PART OF THE STATE IS ERODING AS A FRONT WORKS ON SHORE IN WESTERN
ALASKA. THE LONG WAVE UPPER LEVEL LOW IS ANCHORED WELL INTO EASTERN
RUSSIA AND IS NOT MOVING EASTWARD IN ANY HURRY.
AT THE SURFACE THE HIGH PRESSURE IS CENTERED IN THE YUKON TERRITORIES
AND EXTENDS WESTWARD REACHING ACROSS THE INTERIOR AND INTO BRISTOL
BAY. THE SURFACE LOW PRODUCING THE FRONT IN WESTERN ALASKA IS IN THE
GULF OF ANADYR AND MOVING NORTHEASTWARD. THE NEXT AND STRONGER LOW IS
SOUTHWEST OF ATTU AND IS ALREADY QUITE IMPRESSIVE ON SATELLITE
IMAGERY.

.SHORT TERM FORECAST...THE PRESSURE GRADIENT ALONG THE NORTH GULF
COAST HAS WEAKEN AND LOST ITS UPPER LEVEL SUPPORT RESULTING IN THE
WINDS RAPIDLY WEAKENING THROUGH THE COURSE OF THE DAY. HIS ALLOWED
THE HIGH WIND WARNINGS FROM NORTHEASTERN PRINCE WILLIAM SOUND THROUGH
THE COPPER RIVER DELTA TO BE CANCELED EARLY THIS AFTERNOON.
SNOWFALL IN THE KUSKOKWIM DELTA IS SPREADING EASTWARD INTO THE
KUSKOKWIM VALLEY AND BRISTOL BAY AREA BUT WILL DIMINISH SIGNIFICANTLY
AS IS RUNS INTO THE SURFACE RIDGE. AREAS EAST OF THE ALASKA RANGE
WILL MOSTLY SEE ONLY CLOUDS AS THE RIDGE DISSIPATES AND THE FRONTAL
REMNANTS MOVE EASTWARD.
THE NEXT SIGNIFICANT STORM WILL IMPACT ONLY THE WESTERN ALEUTIANS AND
WESTERN BERING SEA. THERE IS A HIGH WIND WARNING FOR THE WESTERN
ALEUTIAN ISLANDS DUE TO THIS SYSTEM BUT IT WILL MOSTLY IMPACT MARINE
AREAS WITH HURRICANE FORCE WINDS IN THE WESTERN ALEUTIANS EARLY
TOMORROW...WHICH MOVE INTO THE WESTERN BERING SEA TOMORROW AFTERNOON
INTO NIGHT.

.LONG TERM FORECAST...AS DISCUSSED EARLIER THE MODELS ARE STRUGGLING
WITH THE WEEKEND PERIOD AND BEYOND. HOWEVER IT DOES LOOK LIKELY THAT
THE MAIN STORM TRACK DURING THAT PERIOD IN THE NORTHERN BERING SEA
AND THEREFORE KEEP THE BERING SEA REGION AS WELL AS SOUTHWEST ALASKA
IN MORE SOUTHWESTERLY FLOW WHICH WILL KEEP THINGS GENERALLY WARMER
WITH MORE MOISTURE. AREAS EAST OF THE ALASKA RANGE ARE MORE LIKELY TO
STAY ON THE DRY SIDE.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING 191.
MARINE...GALE 138 150 155 160 165 170 171 179 185.
         STORM 130 132 172 175.
         HURRICANE FORCE WIND 176.
         HEAVY FREEZING SPRAY 130 132 138 140.
FIRE WEATHER...NONE.

FEB 11