Heavy Freezing Spray Warning 13, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKST TUE JAN 20 2009

.MODEL DISCUSSION...MODELS IN FAIR AGREEMENT THROUGH ABOUT 72 HOURS.
THE GFS HAS TRENDED A BIT TOWARD THE ECMWF SOLUTION OF DEVELOPING A
CLOSED UPPER LEVEL HIGH OVER NORTHERN ALASKA BY THE END OF THIS WEEK.
NEVERTHELESS...UNCERTAINTY REMAINS ABOVE AVERAGE BEYOND DAY 3. A
SLIGHT BLEND TO THE 00Z GFS WAS USED IN THE SHORT TERM...WITH LITTLE
TO NO CHANGE IN THE MIDRANGE AND LONGRANGE FORECAST.

.ANALYSIS AND UPPER LEVELS...
A LONGWAVE RIDGE REMAINS OVER WESTERN NORTH AMERICA. A WEAKER RIDGE
IS DEVELOPING OVER WESTERN ALASKA AND IS BEGINNING TO CLEAR SKIES
THROUGHOUT MUCH OF MAINLAND ALASKA. A LONGWAVE TROUGH IN THE BERING
SEA IS MOVING SLOWLY EASTWARD WITH TWO MAIN LOW CENTERS...SOUTH OF
ADAK AND WELL SOUTHWEST OF SHEMYA. RAIN AND SNOW SHOWERS ARE
DEPARTING SOUTHCENTRAL AND MOVING NORTHEAST. MOIST SOUTHERLY FLOW
WITH EMBEDDED WAVES ARE CREATING STRONG WINDS AND PRECIP THROUGHOUT
THE CENTRAL ALEUTIANS AND PRIBILOF ISLANDS.

.SHORT TERM FORECAST...
.EAST OF THE ALASKA RANGE...MAIN ISSUE THIS MORNING IS AREAS OF FOG
DEVELOPMENT AS WEAK HIGH PRESSURE MOVES INTO AREAS OF RECENT
RAINFALL. A 1045 MB HIGH OVER NORTHERN ALASKA WILL BEGIN TO MAKE ITS
WAY TOWARD THE CANADIAN YUKON...INCREASING GAP WINDS IN THE USUAL
AREAS BEGINNING TUESDAY EVENING. HIGHEST WINDS WILL LIKELY BE FOUND
EAST OF PRINCE WILLIAM SOUND...INCLUDING VALDEZ...THOMPSON PASS...AND
THE COPPER RIVER DELTA. WINDS ARE NOT EXPECTED TO APPROACH WARNING
LEVEL.

.WEST OF THE ALASKA RANGE...
MAIN CONCERN IS THE CENTRAL ALEUTIANS AND PRIBILOFS...WHERE WIND AND
PRECIP WILL CONTINUE FOR THE NEXT 24-48 HOURS. MOST AREAS WILL BE
WARM ENOUGH TO BE NEARLY ALL RAIN...WITH THE EXCEPTION OF THE
PRIBILOFS WHICH WILL SEE MAINLY SNOW WITH RAIN MIXING IN AT TIMES. NO
WARNING LEVEL WINDS ARE EXPECTED...THOUGH STRONG WIND HEADLINES WILL
CONTINUE AS FAR EAST AS THE KUSKOKWIM DELTA.

.LONG TERM FORECAST...
THOUGH DETAILS ARE STILL SKETCHY...IT LOOKS LIKE A PATTERN CHANGE IS
COMING TO ALASKA. THE WESTERN NORTH AMERICAN RIDGE WILL BE BREAKING
DOWN TO A MORE TRANSIENT FLOW. WHILE THIS WILL BRING TEMPERATURES
BACK TO MORE SEASONAL VALUES...THE EXACT PATH OF INDIVIDUAL LOWS
REMAIN UNCLEAR THROUGH THE WEEKEND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE WARNING...150 155 160 165 170 179 180
         HEAVY FREEZING SPRAY...160
FIRE WEATHER...NONE.

AMD JAN 09