Snow Advisory 19, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM ADT FRI APR 25 2008

.MODEL DISCUSSION...
SOME PREFERENCE TOWARD THE 00Z GFS. GENERAL PATTERN HANDLED DECENTLY
FOR FIRST 84 HOURS OF FORECAST...BUT DETAILS ARE HANDLED DIFFERENTLY
BETWEEN DIFFERENT MODELS AND WITH EACH RUN. THIS IS TO BE EXPECTED
WITH THE COMPLICATED PATTERN DEVELOPING OVER ALASKA AND THE GULF.
MODEL CONFIDENCE DIPS AFTER ABOUT 96 HOURS AS GLOBAL MODELS AND
ENSEMBLES BEGIN TO DIVERGE ON LOCATIONS OF FEATURES IMPORTANT FOR
LOCAL WEATHER.

.ANALYSIS AND UPPER LEVELS...
DEEP ARCTIC LOW CENTERED OVER KOTZEBUE SOUND THIS MORNING MOVING
SOUTHEAST. CYCLONIC FLOW OVER SOUTHERN ALASKA WITH STRONG FLOW ALOFT
FROM THE SOUTHWEST. ANOTHER LOW JUST SOUTH OF GULF MOVING NORTHEAST.
FULL LATITUDE RIDGE ALONG ABOUT 130 DEGREES LONGITUDE...SLOWLY
MOVING EAST AS PRESSURE FROM THE TWO LOWS MOUNTS.

.SHORT TERM FORECAST...
KOTZEBUE SOUND LOW WILL MOVE JUST INLAND IN NORTHWEST ALASKA AND
STALL LATER TODAY. BACKSIDE NORTHERLY JET WILL PUSH INTO THE GULF
TONIGHT AND SATURDAY JOINING WITH THE GULF LOW. DETAILS ON THIS ARE
PROVIDING A NICE FORECAST CHALLENGE. THE OVER-ALL TREND IS FOR THE
GULF LOW TO DEEPEN AND BECOME THE DOMINANT WEATHER FACTOR BY THE END
OF THE WEEKEND.

.LONG TERM FORECAST...
GLOBAL MODELS INDICATE THE GULF LOW WILL MOVE EAST NEXT WEEK. THE
DEPARTURE SPEED AND HOW THINGS DEVELOP BEHIND IT ARE NOT REAL CLEAR.
THE MODELS HANDLE THE MAJOR DEVELOPMENTS IN A SIMILAR WAY BUT
DISAGREE ON SMALLER (BUT IMPORTANT) LOCAL WEATHER FEATURES. FEEL
GOOD ABOUT A DRYING TREND NEXT WEAK AS UPPER FLOW IS WEAK...EVEN
THOUGH CYCLONIC FLOW REMAINS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM WARNING 120.
         GALE WARNING 125 130 132 138 140 141 150 155.
         HEAVY FREEZING SPRAY 160.
FIRE WEATHER...NONE.

LUDWIG APR 08