High Wind in Alaska, December 26, 2010

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 AM AKST SUN DEC 26 2010

.MODEL DISCUSSION...ON THE SYNOPTIC SCALE THE MODELS ARE IN
RELATIVELY GOOD AGREEMENT THROUGH THE SHORT TERM (FIRST 84 HOURS)
FORECAST. DISCREPANCIES ARISE IN REGARDS TO THE MULTIPLE LOW CENTERS
IN THE GULF OF ALASKA FOR THE NEXT 48 HOURS. THE EC AND NAM SEEM TO
HAVE INITIALIZED BETTER THAN THE GFS...AND ALSO GENERALLY AGREE ON
THE TRACK OF THE LOWS. MEANWHILE THE GFS IS AN OUTLIER. THUS THE
FORECAST WILL LEAN TOWARD THE EC/NAM SOLUTION FOR THIS PACKAGE.

.ANALYSIS AND UPPER LEVELS...THE LONGWAVE PATTERN CONTINUES TO
CONSIST OF A DEEP LONGWAVE TROUGH IN THE GULF OF ALASKA AND A RIDGE
OF HIGH PRESSURE IN THE BERING SEA. THE RIDGE IS IN THE PROCESS OF
BECOMING A CLOSED UPPER HIGH OVER SIBERIA...WHICH IS ALLOWING LOWER
HEIGHTS TO INFILTRATE INTO THE CENTRAL BERING SEA. AT THE SURFACE...A
COMPLEX LOW IN THE GULF OF ALASKA IS BRINGING SNOW SHOWERS TO COASTAL
REGIONS AS WELL AS PARTS OF THE COPPER RIVER BASIN AND COOK INLET.
THE PRESSURE GRADIENT BETWEEN THIS LOW AND HIGH PRESSURE IN THE
BERING IS CREATING STRONG WINDS THROUGHOUT MUCH OF THE EASTERN
ALEUTIANS.

.SHORT TERM FORECAST...
.SOUTHCENTRAL...DECAYING SURFACE LOW SUPPORTED BY VORTICITY MAX
MOVING INTO PRINCE WILLIAM SOUND THIS MORNING WILL BRING SNOW SHOWERS
TO THE COAST AND A BRIEF PERIOD OF LIGHT SNOW INLAND. THE ANCHORAGE
AREA WILL LIKELY SEE A DUSTING OF SNOW BY MIDDAY AS THIS FEATURE
MOVES THROUGH THE AREA. SKIES SHOULD BREAK UP TO PARTLY CLOUDY THIS
AFTERNOON ACROSS NON-COASTAL AREAS...ALLOWING TEMPERATURES TO WARM
INTO THE TEENS FOR THE FIRST TIME IN SEVERAL DAYS IN PARTS OF
ANCHORAGE AND THE KENAI PENINSULA.

.SOUTHWEST...COLD NORTHERLY FLOW WILL CONTINUE TODAY. TEMPERATURES
BEGIN TO MODERATE TOMORROW AND WINDS DIMINISH...ALLOWING DANGEROUS
WIND CHILLS IN THE KUSKOKWIM DELTA TO RISE ABOVE DANGEROUS LEVELS BY
MONDAY AFTERNOON. OTHERWISE...BENIGN CONDITIONS AND PARTLY CLOUDY
SKIES WILL PERSIST THROUGH AT LEAST MIDWEEK.

.BERING SEA AND ALEUTIANS...RIDGE OF HIGH PRESSURE EXTENDING DOWN
FROM SIBERIA WILL BEGIN TO RETREAT BACK TO THE NORTH TODAY...ALLOWING
LOWER PRESSURES TO INFILTRATE THE REGION. A STATIONARY FRONT OVER THE
WESTERN ALEUTIANS WILL MAKE SLOW PROGRESS EASTWARD THROUGH
MIDWEEK...AS OVERALL FLOW IN THE BERING SEA BECOMES EASTERLY.

.LONG TERM FORECAST...MODELS NOW CONVERGING ON A LONGWAVE PATTERN
SHIFT TAKING PLACE BY MIDWEEK. THIS WILL CONSIST OF A TROUGH
DEVELOPING IN THE BERING WITH A RIDGE OVER MUCH OF MAINLAND ALASKA.
THIS WILL BRING A RETURN TO MORE SEASONAL TEMPERATURES FOR
SOUTHCENTRAL...AS WELL AS BETTER CHANCES FOR SNOWFALL.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...WIND CHILL ADVISORY 131 155
MARINE...GALE 170 171 176 179 180 185
         HEAVY FREEZING SPRAY 121 138 140 150 155 160 165 179 180 185

FIRE WEATHER...NONE

AMD DEC 10