Gale Warning 379, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
400 PM AKDT FRI APR 3 2009

.MODEL DISCUSSION...MODELS ARE DOING WELL THROUGH THE WEEKEND AND
THEN STEADILY BECOME MORE SUSPECT TOWARD THE MIDDLE OF NEXT WEEK. THE
GFS MODEL HAS BEEN SHOWING GOOD RUN TO RUN CONSISTENCY THE LAST THREE
MODEL RUNS.

.ANALYSIS AND UPPER LEVELS...AN UPPER LEVEL TROUGH EXTENDS OVER THE
CENTRAL PART OF THE STATE AND INTO THE GULF OF ALASKA WITH AN UPPER
LEVEL RIDGE OVER THE CENTRAL BERING SEA. THE JET STREAM IS BETWEEN
THESE TOW FEATURES IS APPROACHING 150 KT AT 250 MB AND WILL INCREASE
SOME OVER THE NEXT DAY. THE JET HAS A FAIRLY HIGH AMPLITUDE AS IT
CURVES AROUND THE RIDGE. THIS PATTERN WILL PERSIST UNTIL THE UPPER
RIDGE IS PUSHED SOUTH OF THE AREA ON SUNDAY.

SURFACE...A DOUBLE CENTERED LOW WITH ONE CENTER IN THE GULF OF ALASKA
AND THE OTHER CONSIDERABLY SOUTH OF THERE IS BRINGING A LARGE AMOUNT
OF MOISTURE INTO THE GULF REGION. PRESSURE GRADIENTS ARE TIGHT AROUND
THE GULF COAST THROUGH THE ALASKA PENINSULA WITH THIS LOW COMPLEX. AN
INVERTED SURFACE TROUGH IS PROTRUDING INTO SOUTH CENTRAL ALASKA AND
WILL EDGE INTO THE COPPER RIVER BASIN OVERNIGHT.
A STRONG LOW IS ALSO RESIDING SOUTHWEST OF THE ALEUTIAN ISLANDS AND
WILL SLOWLY WEAKEN AS IT MOVES INTO THE CENTRAL BERING SEA SUNDAY.
BETWEEN THESE TWO LOWS IS A HIGH AMPLITUDE RIDGE IN THE CENTRAL
BERING SEA WHICH WILL MOVE INTO THE INTERIOR OF THE STATE THIS
WEEKEND.

.SHORT TERM FORECAST... THE DEVELOPMENT OF THE LOW IN THE GULF HAS
BROUGHT A STRONG FRONT TO THE KODIAK ISLAND REGION AND ALONG THE
NORTH GULF COAST. THE SNOW AND BLOWING SNOW THROUGH EARLY AFTERNOON
HAS NOT BEEN QUITE TO THE POINT OF BLIZZARD CONDITIONS BUT THE WINDS
SHOULD CONTINUE TO INCREASE INTO THE EVENING. COLD ADVECTION WILL
ALSO INCREASE AND DROP THE TEMPERATURE...THEREFORE THERE IS STILL A
GOOD CHANCE OF THE BLIZZARD PANNING OUT.
AN ITEM TO WATCH IN THE COOK INLET REGION IS WHETHER THE INVERTED
TROUGH WILL BEGIN TO BRING SNOW BACK INTO ANCHORAGE AND COOK INLET
THIS EVENING AS THE LOW IN THE GULF MOVES EASTWARD.
SNOW HAS MOVED OUT OF THE BRISTOL BAY AREA BUT GUSTY NORTH WINDS WILL
REMAIN THROUGH THE NIGHT.
SNOW IN THE WESTERN ALEUTIANS WILL TURN TO RAIN IN THE WARM ADVECTION
WITH THE FRONT MOVING INTO THE AREA. THIS PRECIPITATION WILL SPREAD
EASTWARD AND REACH THE ALASKA PENINSULA BY SATURDAY NIGHT.

.LONG TERM FORECAST...STILL EXPECTING THE PROGRESSIVE PATTERN TO SLOW
IN RESPONSE TO AMPLIFYING JET STREAM. FOR THE BEGINNING OF THE
WEEK...AN UPPER TROUGH WILL BECOME ESTABLISHED OVER THE BERING. THE
MAIN FEATURE OF INTEREST IN THE LONG TERM LOOKS TO BE THE LARGE
LOW MOVING INTO THE BERING SEA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 171.
MARINE...GALE 120 130 150 155 170 172 175 176 185.
         STORM 132.
         HEAVY FREEZING SPRAY 130 140 165.
FIRE WEATHER...NONE.

APR 09