Heavy Freezing Spray Warning 71, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 PM AKST THU FEB 24 2011

.MODEL DISCUSSION...MODELS CONTINUE TO DO WELL AS THEY ARE IN GOOD
AGREEMENT WITH EACH OTHER AND SHOW GOOD RUN TO RUN CONSISTENCY.

.ANALYSIS AND UPPER LEVELS...THE BIG WEATHER FEATURE IN THE STATE IS
A STRONG LOW THAT IS MOVING INTO THE NORTHWEST PART OF THE STATE.
THE UPPER LEVEL RIDGE OVER SOUTH CENTRAL ALASKA IS BREAKING DOWN AS
FLOW BECOMES MORE ZONAL DUE TO THE STRONG STORM IN NORTHWEST ALASKA.
THE JET STREAM IS HELPING TO FUEL THIS SYSTEM WITH STRONG SOUTHWEST
FLOW BETWEEN THE LOW AND THE RIDGE IN WESTERN ALASKA. THE JET STREAM
THEN RIDES OVER THE TOP OF THE RIDGE AND AROUND TO MOVE THROUGH
SOUTHEAST ALASKA FROM THE NORTH. THE FRONT ASSOCIATED WITH THIS LOW
IS CONTINUING TO SLOWLY PROGRESS EAST ACROSS THE EASTERN BERING AND
IS STILL BRINGING SOME STRONG WINDS AND PRECIPITATION WITH IT. A NEW
RIDGE WILL LIKELY DEVELOP INTO AN OMEGA BLOCK PATTERN THIS WEEKEND.

.SHORT TERM FORECAST...STRONG WINDS PERSIST IN SOUTHWEST ALASKA IN
ADVANCE OF THE COLD FRONT IN THE BERING SEA. WINDS WILL DIMINISH SOME
OVERNIGHT AS THE FRONT WEAKENS AND MOVES EASTWARD. THERE IS A BIT OF
RAIN AHEAD OF THIS FRONT WITH SNOW AT HIGHER ELEVATIONS.
PRECIPITATION TURNS TO ALL SNOW BEHIND THE FRONT. THIS SYSTEM WILL
MOVE INTO SOUTH CENTRAL ALASKA OVERNIGHT BRINGING A CHANCE OF SNOW
AFTER MIDNIGHT. THERE MAY BE SOME RAIN MIXED IN OVER THE KENAI
PENINSULA BUT IT LOOKS LIKE ANY RAIN WILL BE OF SHORT DURATION BEFORE
COLD AIR MOVES IN FROM THE WEST. FROM ANCHORAGE NORTH PRECIPITATION
SHOULD BE ALL SNOW AND SNOWFALL WILL BE HEAVIER THE FURTHER NORTH ONE
GOES. A DECENT AREA OF STRATUS HAS DEVELOPED IN COOK INLET AND
EXTENDING INTO THE SUSITNA VALLEY. THIS WILL LIKELY REMAIN IN PLACE
UNTIL THE FRONT PASSES AND TURNS FLOW MORE TO THE NORTHWEST.

.LONG TERM FORECAST...THE BERING SEA UPPER RIDGE WILL BECOME A CLOSED
HIGH SUNDAY AND BOTH ECMWF AND GFS KEEP IT NEARLY STATIONARY CENTERED
NEAR BERING STRAIT THROUGH AT LEAST NEXT WEDNESDAY. A 1050-1055 MB
SURFACE HIGH IS FORECAST TO BUILD OVER THE INTERIOR SUN...THEN SLIDE
SE INTO YUKON MONDAY. A SURFACE TROUGH FORECAST TO LIE ALONG EASTERN
GULF COAST COMBINED WITH MODERATE TO STRONG N TO NE FLOW FROM 850 MB
ON UP...WILL LEAD TO GUSTY OUTFLOW WINDS THROUGH COASTAL PASSES AND
GAPS. COLDEST AIR OVER MAINLAND WILL BE SUN/MON...THEN 500 MB HEIGHTS
INCREASE BY TUE/WED AS UPPER RIDGE EXPANDS A LITTLE FURTHER E FROM
BERING SEA. DRY WEATHER WITH BELOW-AVERAGE TEMPERATURES SUN AND
MON OVER MOST OF THE MAINLAND S OF THE AK RANGE...WITH SOME
MODERATION IN TEMPERATURES LIKELY BY TUE/WED. ANOTHER WEAK LOW WILL
MOVE N OVER CENTRAL AND WESTERN ALEUTIANS MON...WITH RAIN ONLY AS FAR
EAST AS ADAK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 120 129 130 132 165 172 175 176.
         HEAVY FREEZING SPRAY 121 129 185.
FIRE WEATHER...NONE.

FEB 11