Gale Warning 903, NWS Anchorage, AK

SOUTH CENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKST TUE NOV 23 2010

.MODEL DISCUSSION...THE NAM DIFFERS FROM THE GFS UKMET AND ECMWF WITH
THE LOW TRACKING INTO THE NORTHERN GULF OF ALASKA.  OTHERWISE THE
MODELS ARE IN GOOD AGREEMENT THROUGH THU.  THE NAM AND GFS ENSEMBLE
MEMBERS TRACK THE LOW FARTHER NORTH INTO PRINCE WILLIAM SOUND AS
OPPOSED TO THE NORTHERN GULF WEST OF KODIAK.  THE NAM SOLUTION IS
MORE FAVORABLE FOR SNOW FOR SOUTH CENTRAL AS COLD AIR RETURNS TO THE
AREA FROM THE NORTHWEST.

.ANALYSIS AND UPPER LEVELS...THE PATTERN IS PROGRESSIVE.  SYSTEMS ARE
FORECAST TO MOVE FROM WEST TO EAST ACROSS SOUTHERN ALASKA. THIS
AFTERNOON HAS A HIGH AMPLITUDE RIDGE OVER THE EASTERN MAINLAND AND
GULF AND A TROUGH OF LOW PRESSURE OVER THE EASTERN BERING SEA. THE
BERING TROUGH IS FORECAST TO REPLACE THE RIDGE BY THU BRING COLDER
AIR AND THE LIKELYHOOD OF SNOW TO THE SOUTHERN MAINLAND. A FLAT RIDGE
WILL PASS OVER THE MAINLAND FRIDAY. A COLD TROUGH WILL MOVE FROM THE
NORTHWEST TO BE OVER THE CENTRAL MAINLAND BY SATURDAY. WITH THIS
TROUGH COMES ANOTHER CHANCE OF SNOW FOR SOUTHERN ALASKA. THIS TROUGH
IS FORECAST TO BECOME ALMOST STATIONARY AND REMAIN CENTERED OVER
CENTRAL ALASKA UNTIL AT LEAST TUESDAY.

.SHORT TERM FORECAST...
SOUTHWEST...WET AND WARM TONIGHT WITH RAIN CHANGING OVER TO SNOW AND
BECOMING SHOWERS ON WED. A RETURN TO MORE SEASONABLE TEMPERATURES
STARTING ON WED...A CHANCE OF SNOW FRIDAY...AND GETTING COLDER OVER
THE WEEKEND.

SOUTH CENTRAL...WET AND WARM TONIGHT THEN STARTING TO COOL DOWN LATE
WED PM WITH CONTINUED COOLING INTO THU. RAIN WILL CHANGE TO SNOW WITH
A GOOD CHANCE OF SNOW WED NIGHT AND THURSDAY. TEMPERATURES SHOULD
REMAIN COOL WITH ANOTHER CHANCE OF SNOW OVER THE WEEKEND

.LONG TERM FORECAST...
THE UPPER AIR PATTERN IS FORECAST TO BECOME MORE STATIONARY OVER THE
WEEKEND AND INTO NEXT WEEK WITH A RIDGE BUILDING OVER THE BERING SEA
AND A TROUGH OVER THE MAINLAND WITH AN UPPER LOW OVER THE GULF.  LOOK
FOR COLDER AND DRYER WEATHER FOR SOUTHWESTERN ALASKA AND POSSIBLE
SNOW ON THE WEEKEND THEN COLDER FOR SOUTH CENTRAL.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 132  150 155 160 165 180 170 171 172 175 185 179
FIRE WEATHER...NONE

RHH NOV 10