Blizzard Watch 24, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
400 AM AKDT FRI MAR 20 2009

.ANALYSIS AND UPPER LEVELS...
STUBBORN BLOCKING RIDGE OVER NORTHEAST SIBERIA (REX CONFIGURATION)
WITH ASSOCIATED DOWNSTREAM TROUGH ALONG 140 DEGREES WEST LONGITUDE
AND A CLOSED CIRCULATION LOW OVER THE NORTHEAST GULF OF ALASKA. COLD
ADVECTION IN NORTHERLY FLOW FROM THE EASTER ALEUTIANS TO NEARLY THE
CANADIAN BORDER. LOW UNDERCUTTING THE SIBERIAN BLOCK CREATING WARM
ADVECTION OVER THE CENTRAL AND WESTERN ALEUTIANS.

.SHORT TERM FORECAST...
SIBERIAN BLOCK WILL SLOWLY RETROGRADE OVER THE NEXT FEW DAYS AND
TAKE ON MORE OF AN OMEGA LOOK AS THE LOW SOUTH OF THE WESTERN
ALEUTIANS CONNECTS WITH THE GULF LOW. MOST OF THE PRECIPITATION WILL
STAY SOUTH OF MAINLAND ALASKA THROUGH SATURDAY. SATURDAY NIGHT AND
SUNDAY THE MEAN TROUGH POSITION WILL FOLLOW THE RETROGRATION OF THE
SIBERIAN BLOCK AND ALLOW MORE MOISTURE TO MOVE INTO SOUTHERN ALASKA
FROM THE EAST AS SOUTHERLY FLOW DEVELOPS IN CYCLONIC FLOW.

.LONG TERM FORECAST...
THE ENTIRE PATTERN WILL CONTINUE TO SLOWLY RETROGRADE THROUGH NEXT
WEEK. ALTHOUGH THE NUMERICAL MODELS AGREE ON THE OVERALL PATTERN...
THE DETAILS IN HOW THE LOW ORIENTS ITSELF AND TIMING OF SHORT WAVE
FEATURES ARE NOT SO WELL DECIDED UPON. BASICALLY THE MEAN UPPER
TROUGH POSITION WILL BE ROUGHLY OVER THE EASTERN BERING SEA AND
CYCLONIC FLOW WILL DOMINATE THE ENTIRE STATE AND MOST OF THE BERING
SEA AND GULF OF ALASKA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM WARNING 175 176.
         GALE WARNING 170 172.
         HEAVY FREEZING SPRAY 138 150 155 165 170 179.
FIRE WEATHER...NONE.

LUDWIG MAR 09