Heavy Freezing Spray Warning 92, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 PM AKST SUN FEB 26 2012

.ANALYSIS AND UPPER LEVELS...RATHER PROGRESSIVE PATTERN WITH THE JET
STREAM OVER THE ALEUTIANS AND THEN TURING NORTHEAST OVER THE GULF OF
ALASKA. SATELLITE CONTINUES TO SHOW A DEEP MOISTURE FEED INTO THE
FRONT MOVING THROUGH THE GULF THIS AFTERNOON. IN ADDITION TO THE DEEP
MOISTURE THERE IS ENOUGH COLD AIR IN THE GULF REGION TO KEEP MOST OF
THE PRECIPITATION SNOW.
THE PARENT LOW IS IN THE BRISTOL BAY REGION AND MOVING EASTWARD. THE
AIR BEHIND THIS LOW IS QUITE COLD AND IS DROPPING THE TEMPERATURES IN
THE PRIBILOF ISLANDS THROUGH THE DAY AS THE STRONG NORTHWEST WINDS
KICK UP...CAUSING BLIZZARD CONDITIONS THERE. SOUTHWEST ALASKA WILL
BEGIN TO GET INTO THIS COLDER AIR OVERNIGHT AS THE WINDS ROTATE
AROUND TO THE NORTHWEST. THERE IS STILL A QUESTION AS TO WHETHER
THERE WILL BE BLIZZARD CONDITIONS PERSISTING ALONG THE KUSKOKWIM
DELTA COAST TONIGHT WHEN THE COLD ADVECTION MOVES IN...OR WHETHER THE
FRONTAL BOUNDARY BETWEEN BETHEL AND THE COAST WILL CUT OFF THE
SNOWFALL COMPLETELY AS IT MOVES EASTWARD.

.MODEL DISCUSSION...MODELS ARE DOING WELL AND ARE CONSISTENT IN THEIR
SOLUTIONS FROM THE 12Z RUNS. RUN TO RUN CONSISTENCY HAS BEEN GOOD AS
WELL.

.SHORT TERM FORECAST...THE KACHEMAK BAY AREA HAS MIXED WITH RAIN BUT
THAT IS ABOUT THE ONLY PLACE. CORDOVA WAS EXPECTED TO TURN TO OR MIX
WITH RAIN THIS AFTERNOON BUT INSTEAD REMAINED SNOW THROUGH MID
AFTERNOON. THIS ALLOWED HEAVY SNOW AND WIND TO COMBINE FOR BLIZZARD
CONDITIONS AND HEAVY SNOWFALL. VALDEZ HAS BEEN EXPERIENCING MODERATE
TO HEAVY SNOWFALL THROUGH THE DAY AND WILL GRADUALLY IMPROVE
OVERNIGHT AFTER THE UPPER WAVE PASSES TO THEIR EAST LATE THIS
EVENING.
THE STORY IN THE ANCHORAGE AREA HAS BEEN DICTATED BY THE DOWNSLOPE
WINDS OFF THE CHUGACH MOUNTAINS. UPPER LEVEL FLOW WAS CONDUCIVE FOR A
HEAVY SNOWFALL BUT THE DOWNWARD MOTION OF THE WINDS OFF THE MOUNTAINS
IN THE STRONG EAST TO SOUTHEAST WINDS KEPT THE PRECIPITATION LIGHT
OVER TOWN AND IN EAGLE RIVER. SNOWFALL WILL INCREASE IN INTENSITY
DURING THE EVENING AS THE WINDS DIMINISH BUT THE LIFTING WILL ALSO
DIMINISH AROUND MIDNIGHT LEAVING ONLY MODEST SNOWFALL AMOUNTS IN THE
2 TO 4 INCH RANGE TONIGHT FOR THE ANCHORAGE AREA.

SOUTHWEST ALASKA WILL BEGIN TO GET INTO THIS COLDER AIR OVERNIGHT AS
THE WINDS ROTATE AROUND TO THE NORTHWEST. THERE IS STILL A QUESTION
AS TO WHETHER THERE WILL BE BLIZZARD CONDITIONS PERSISTING ALONG THE
KUSKOKWIM DELTA COAST TONIGHT WHEN THE COLD ADVECTION MOVES IN...OR
WHETHER THE FRONTAL BOUNDARY BETWEEN BETHEL AND THE COAST WILL CUT
OFF THE SNOWFALL COMPLETELY AS IT MOVES EASTWARD.
THE PRIBILOF ISLANDS WILL NOT SEE MUCH IMPROVEMENT IN THEIR BLIZZARD
CONDITIONS UNTIL THE PRESSURE GRADIENT RELAXES SIGNIFICANTLY TOWARD
MORNING.

.LONG TERM FORECAST...AN ACTIVE WEATHER PATTERN REMAINS ON TAP FOR
THE REGION THROUGH THE MIDDLE PART OF THE WEEK INTO NEXT WEEKEND. A
STORM FORCE FRONT WILL FALL APART AS IT EXTENDS TO THE EASTERN BERING
TUESDAY INTO WEDNESDAY. A STRONG SOUTHWESTERLY JET WILL PUSH THE NEXT
DEVELOPING SYSTEM NORTH AND EAST ACROSS THE NORTH PACIFIC NEAR THE
ALEUTIANS AND THEN INTO THE GULF OF ALASKA BY NEXT WEEKEND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 125 131 135 195.
         WINTER STORM WARNING FOR HEAVY SNOW 145.
MARINE...GALE 120 132 138 150 155 160 165 170 171 172 176 179 180 185
         STORM 130 175
         HEAVY FREEZING SPRAY 165 179.
FIRE WEATHER...NONE.

FEB 12