Heavy Freezing Spray Warning 217, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKST FRI NOV 30 2012

.MODEL DISCUSSION...
GUIDANCE IS IN GOOD AGREEMENT ONCE AGAIN FOR THE SHORT TERM PORTION
OF THE FORECAST. FOR THE AFTERNOON FORECAST PACKAGE THE NAM WAS
GENERALLY USED FOR ITS BETTER REPRESENTATION OF SMALL SCALE
FEATURES.

.ANALYSIS AND UPPER LEVELS...
THERE IS A STRONG UPPER LEVEL RIDGE OVER THE BERING SEA. THERE IS AN
UPPER LEVEL LOW OVER THE NORTHWEST TERRITORIES OF CANADA WITH AN
ATTACHED LOW OVER THE YUKON TERRITORY. A TROUGH STRETCHES FROM THE
YUKON LOW INTO THE NORTHERN GULF OF ALASKA. STRONG WINDS OVER THE
MATANUSKA VALLEY AND THROUGH THE VALDEZ AREA ARE AIDED BY STRONG
PRESSURE/TEMPERATURE GRADIENTS AND UPPER LEVEL SUPPORT.

.SHORT TERM FORECAST...
STRONG WINDS OVER THE MATANUSKA VALLEY WILL DIMINISH TONIGHT AS THE
UPPER LEVEL SUPPORT DECREASES. STRONG WINDS WILL CONTINUE IN THE
VALDEZ AREA THROUGH TONIGHT AS THEY REMAIN CLOSER TO THE UPPER LEVEL
TROUGH. AS THE TROUGH MOVES SOUTH SATURDAY MORNING WINDS WILL
DIMINISH THERE AS WELL. THERE WILL STILL BE SOME WINDS THROUGH THESE
AREAS AS THE OVER-ALL PATTERN KEEPS THE GRADIENT IN PLACE...BUT THEY
WILL BE WELL BELOW THEIR CURRENT VALUES.

THE UPPER LEVEL RIDGE WILL REMAIN BASICALLY IN PLACE THROUGH THE
WEEKEND WITH NORTHERLY FLOW OVER SOUTHERN ALASKA. HOWEVER...THERE
WILL BE A SUBTLE SHIFT IN THE PATTERN AS THE RIDGE GOES FROM
POSITIVELY TILTED (NUDGING ACROSS CENTRAL ALASKA) TO NEGATIVELY
TILTED (NUDGING INTO EXTREME NORTHEAST RUSSIA) BY THE END OF
WEEKEND INTO MONDAY. THIS WILL ALLOW THE YUKON LOW TO SLIDE WESTWARD
AND BEGIN TO CARVE OUT AN UPPER LEVEL LOW OVER SOUTHERN ALASKA AND
THE NORTHERN GULF.

FOR SOUTH CENTRAL ALASKA...SOME HIGH CLOUDS ARE EXPECTED ON THE
WEEKEND AND INTO MONDAY...BUT NO PRECIPITATION...AS NORTHERLY FLOW
ALOFT CONTINUES.

FOR SOUTHWEST ALASKA...A COUPLE OF WEAK SHORT WAVES IN THE NORTHERLY
FLOW WILL SLIDE SOUTHWARD ACROSS SOUTHWEST ALASKA ON THE WEEKEND.
THIS WILL BRING JUST A SLIGHT CHANCE OF PRECIPITATION TO THE
KUSKOKWIM VALLEY/DELTA AREA SATURDAY AND SATURDAY NIGHT.
PRECIPITATION WILL BE LIKELY FOR THE ALASKA PENINSULA LATE SATURDAY
NIGHT THROUGH SUNDAY AS THOSE SYSTEMS MOVE INTO THE GULF OF ALASKA.

.LONG TERM FORECAST...
THE BERING SEA RIDGE WILL RETROGRADE INTO NORTHEAST RUSSIA BY THE
MIDDLE OF THE WEEK. THIS WILL ALLOW THE SOUTHERN ALASKA LOW TO
SETTLE IN OVER SOUTHWEST ALASKA. THIS WILL ALLOW A CHANCE OF
PRECIPITATION OVER SOUTH CENTRAL ALASKA FOR THE MIDDLE TO LATTER
PORTION OF NEXT WEEK...MAINLY COASTAL AREAS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING 111 131 135.
MARINE...STORM WARNING 127 128.
         GALE WARNING 121 126 130 132 150 155.
         HEAVY FREEZING SPRAY 121 129 130 140 141 160.
FIRE WEATHER...RED FLAG WARNING 111.

LUDWIG NOV 12