Wind Chill Advisory 15, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKST SAT DEC 27 2008

.MODEL DISCUSSION...MODELS IN GOOD AGREEMENT THROUGH 120 HOURS. GFS
IS OPERATIONAL MODEL OF CHOICE.

.UPPER LEVELS...
THE UPPER LEVEL LONG WAVE TROUGH OVER CENTRAL AND EASTERN ALASKA AND
THE GULF WILL SLOWLY MIGRATE EASTWARD INTO WESTERN CANADA BY 120
HOURS. RIDGE OF HIGH PRESSURE ALOFT THAT EXTENDS ACROSS THE CENTRAL
ALEUTIANS AND BERING SEA HOLDS THROUGH 120 HOURS.

.SURFACE FEATURES...
A 978 MB LOW JUST SOUTH OF CAPE YAKATAGA WILL GRADUALLY WEAKEN AS IT
TRACKS SOUTHEAST TOWARD THE SOUTHERN PANHANDLE AND THEN DISSIPATES
OVER WESTERN CANADA BY WED AFTERNOON. AS THE PRIMARY LOW CENTER MOVES
OFF TO THE EAST A BROAD AREA OF WEAK COMPLEX LOW PRESSURE WILL
DEVELOP IN ITS WAKE OVER THE GULF OF ALASKA. A RIDGE OF HIGH PRESSURE
WILL HOLD OVER THE CENTRAL BERING SEA THROUGH MON NIGHT. THE RAPIDLY
OCCLUDING WARM FRONT POISED TO MOVE INTO THE WESTERN ALEUTIANS THIS
MORNING WILL STALL OUT OVER THE SOUTHWESTERN BERING SEA AND CENTRAL
ALEUTIANS THIS EVENING.

.FORECAST ELEMENTS...
TIGHT PRESSURE GRADIENT OVER SOUTHCENTRAL AND SOUTHWESTERN ALASKA
SHOULD GRADUALLY SLACKEN AS THE LOW CENTER IN THE GULF OF ALASKA
WEAKENS AND MOVES OFF SOUTHEASTWARD. NORTHERLY GAP WINDS WILL
DIMINISH THROUGH TODAY AND TONIGHT AND FLOW WILL BECOME INCREASINGLY
WESTERLY. LOW VISIBILITIES IN BLOWING SNOW STILL A CONCERN THROUGH
THOMPSON PASS...PORTAGE VALLEY...AND ACROSS THE KUSKOKWIM DELTA.
COLD AIR ADVECTION ACROSS THE EASTERN BERING SEA...ALASKA
PENINSULA...AND EASTERN ALEUTIANS WILL CONTINUE TO SPREAD SCATTERED
SNOW SHOWERS ACROSS THESE AREAS. PERIODIC SNOW SHOWERS COMBINED WITH
AREAS OF BLOWING SNOW MAY BRIEFLY REDUCE VISIBILITIES TO AROUND ONE
HALF MILE AT TIMES. CONDITIONS EXPECTED TO CONTINUE THROUGH MONDAY
WHEN WINDS SHIFT FROM NORTHWEST TO NORTHEAST.
SOUTHEAST WINDS AHEAD OF THE WEATHER FRONT OUT WEST WILL SPREAD BOTH
RAIN AND SNOW ACROSS THE WESTERN ALEUTIANS THIS MORNING. CONDITIONS
ARE EXPECTED TO CONTINUE THROUGH MONDAY WHEN THE FRONT FINALLY
DISSIPATES.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 121 129 130 132 138 150 155 160 165 170 171 175 180
         STORM 176
         HEAVY SPRAY 121 129 130 132 138 140 141 150 160 165 180 185
FIRE WEATHER...NONE.

ASB DEC 08