Gale Warning 1071, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 AM AKST MON DEC 20 2010

.MODEL DISCUSSION...MODELS IN VERY GOOD AGREEMENT THROUGH 120 HOURS.
GFS PREFERRED THROUGH THE SHORT TERM FOR CONSISTENCY. TRENDED INTO
THE HPC SOLUTION IN THE MID AND LONG RANGE.

.ANALYSIS AND SHORT TERM FORECAST...
REMNANTS OF OCCLUDED FRONT EXTEND FROM THE NORTHERN SUSITNA VALLEY TO
PRINCE WILLIAM SOUND AND INTO THE GULF. FEATURE IS DRIFTING SLOWLY
EASTWARD AS IT GRADUALLY DETERIORATES. FRONT LEVEL 1 TO 3 INCHES OF
SNOW IN ITS WAKE ACROSS THE SUSITNA VALLE...MAT VALLEY...AND
ANCHORAGE BOWL OVERNIGHT BUT PRECIPITATION IS BEGINNING TO TAPER OFF
AND PARTLY SUNNY SKIES ARE EXPECTED ACROSS WHOLE OF SOUTHCENTRAL BY
LATE AFTERNOON.
999 MB LOW JUST WEST OF SHEMYA MAINTAINS INTENSITY AS IT MOVES ACROSS
THE WESTERN ALEUTIANS TODAY. GALE FORCE WINDS AND A MIX OF RAIN AND
SNOW ASSOCIATED WITH THIS SURFACE...BUT PATH OF LOW SHOULD MINIMIZE
ITS IMPACT ON ALEUTIAN SETTLEMENTS.
COMPLEX LOW PRESSURE HOLDS OVER THE GULF OF ALASKA THROUGH TUESDAY.
HIGH PRESSURE BUILDS OVER THE BERING SEA ON TUESDAY. GAP WINDS
THROUGH NORTH AND NORTHEASTERN CHANNELS WILL RETURN IN FORCE ON
TUESDAY...AND CONTINUE THROUGH THE WEEKEND.

.UPPER LEVELS AND LONG TERM FORECAST...
LONG WAVE TROUGH OVER MAINLAND ALASKA DEEPENS THROUGH TUESDAY NIGHT
WHILE STRONG UPPER LEVEL RIDGE BUILDS OVER THE ALEUTIANS AND BERING
SEA. STRONG COLD ADVECTION ALONG ALASKAS WEST COAST AND THE EASTERN
BERING SEA WILL KNOCK TEMPERATURES OVER MAINLAND SOUTHWEST ALASKA
INTO THE SUBZERO RANGE AGAIN AS THE HOLIDAY WEEKEND APPROACHES.
SURFACE GRADIENT ACROSS SOUTHERN ALASKA AND THE EASTERN GRADIENT
TIGHTENS DRAMATICALLY WEDNESDAY MORNING AS SURFACE HIGH OVER BERING
ATTEMPTS TO PRESS EASTWARD. GAP WINDS THROUGH NORTH AND NORTHEASTERN
CHANNELS WILL RETURN IN FORCE ON WEDNESDAY AND CONTINUE THROUGH
SATURDAY. UPPER LEVEL SHORT WAVE MIGRATING DOWN THE EASTERN FLANK OF
THE UPPER LEVEL RIDGE WILL ENHANCE NORTHERLY FLOW AT THE SURFACE.
POTENTIAL FOR WARNING LEVEL WINDS THROUGH ALASKA PENINSULA CHANNELS
ON WEDNESDAY WHERE SURFACE FORCING AND UPPER LEVEL SUPPORT WILL BE
MAXIMIZED. OTHERWISE CLEAR AND COLD FOR MOST MAINLAND AREAS. AREAS OF
STRATUS AND FOG DEVELOPING OVER THE BERING.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 121 130 132 150 160 172 175 179 352 411 412 413 414
         HEAVY SPRAY 121 129 130 140 141 414
FIRE WEATHER...NONE.

ASB DEC 10