Gale Warning 353, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKDT SAT APR 11 2009

.ANALYSIS AND UPPER LEVELS...
LONGWAVE TROUGH CONTINUES TO BE SITUATED OVER THE MAINLAND WITH A
RIDGE BUILDING IN TO THE WEST OVER THE BERING SEA. THIS IS A
VERTICALLY STACKED PATTERN WITH SIMILAR POSITIONING OF THE SURFACE
LOW AND SURFACE RIDGE. COLD AIR ADVECTION ALONG THE WEST COAST
CONTINUES TO FEED THE SURFACE LOW BUT WILL GRADUALLY DECREASE AS THE
HIGH SHIFTS NORTHWARD AND BECOMES MORE CUT OFF FROM THE MAIN PATTERN.
UNSTABLE CONDITIONS WILL PERSIST OVER THE MAINLAND WITH THE COLD AIR
ADVECTION ALOFT AND WARMER TEMPERATURES AT THE SURFACE DUE TO
INCREASED DIURNAL HEATING.

.MODEL DISCUSSION...
IN THE SHORT TERM LITTLE DIFFERENCES CONTINUE BETWEEN THE MODEL
SOLUTIONS.  GFS WAS AGAIN USED AS THE MODEL OF THE DAY IN THE EAST
AND WEST. AFTER 60 HOURS THE MODELS SEEM TO HAVE DIFFICULTY RESOLVING
THE MULTIPLE LOWS FORECAST TO MOVE ACROSS THE ALEUTIANS ALTHOUGH ALL
MODELS INDICATE A SIMILAR TRACK.  HPC GUIDANCE WAS USED PAST THE 60
HOUR POINT AS IT HAS BEEN MOST CONSISTENT AND USES A BROADER SOLUTION
FOR THE MULTIPLE LOW CENTERS.

.SHORT TERM FORECAST...
EAST OF THE ALASKA RANGE...SHOWERY CONDITIONS WILL CONTINUE IN THE
EAST TODAY AS THE UNSTABLE LOW PRESSURE SYSTEM REMAINS OFF THE SHORE
OF KODIAK.  SEVERAL SHORTWAVES MOVING THROUGH THE SYSTEM ARE FORECAST
TO BRING BANDS OF PRECIPITATION THROUGH THE REGION...THIS PRECIP
SHOULD BE HEAVIEST ALONG THE GULF COAST AND THE WESTERN EDGE OF THE
PRINCE WILLIAM SOUND.  TEMPERATURES ARE STILL RELATIVELY COOL ALOFT
SO CLOUDY CONDITIONS WILL KEEP THE BOUNDARY LAYER COLD ENOUGH TO SEE
RAIN MIXING WITH SNOW ACROSS THE AREA. OTHERWISE WINDS ARE TAPERING
OFF AS THE LOW WEAKENS AND ONLY SMALL CRAFT ADVISORIES ARE EXPECTED
FOR THE EASTERN MARINES.

WEST OF THE ALASKA RANGE...BANDS OF PRECIPITATION CONTINUE THIS
MORNING ACROSS THE KUSKOKWIM DELTA AND BRISTOL BAY BUT ARE EXPECTED
TO SLOWLY TAPER OFF THROUGH OUT THE DAY.  GUSTY NORTH WINDS WILL PICK
UP ALONG THE KUSKOKWIM DELTA AS THE RIDGE SHIFTS EASTWARD...HOWEVER
WITH THE WEAKENING LOW THE WINDS SHOULD SLOWLY DIMINISH AS WELL.  IN
THE BERING SNOW SHOWERS WILL CONTINUE AS THE RIDGE SLOWLY MOVES
OVERHEAD.  BLOWING SNOW SHOULD CEASE IN THE PRIBILOFS TONIGHT AS THE
RIDGE AXIS MOVES IN AND THE TIGHTENED GRADIENT MOVES OFF TO THE EAST.
SATELLITE INDICATES THAT THE FRONT ASSOCIATED WITH THE NEXT LOW
PRESSURE SYSTEM SOUTHWEST OF SHEMYA IS ALREADY APPROACHING...THIS
FRONT IS EXPECTED TO MOVE INTO THE CENTRAL ALEUTIANS BY TOMORROW
MORNING.  GALE FORCE WINDS CAN BE EXPECTED IN THE VICINITY OF THE
FRONT.

.LONG TERM FORECAST...
THE RIDGE BUILDING INTO THE CENTRAL BERING TODAY WILL SHIFT SLIGHTLY
NORTHWARD BY MONDAY AND ALLOW THE LOW PRESSURE IN THE WESTERN BERING
TO MOVE EASTWARD.  HOWEVER BY TUESDAY THE RIDGE BEGINS TO SLIDE BACK
TOWARD THE EAST AND THE LOW GETS PUSHED SOUTH OF THE ALEUTIAN CHAIN
AND GRADUALLY INTO THE GULF OF ALASKA.  CONDITIONS WILL REMAIN CALM
FOR THE BERING...BUT LOOK TO STAY SHOWERY ACROSS THE MAINLAND AS
GENERAL LOW PRESSURE REMAINS IN THE GULF THROUGH MID NEXT WEEK.

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

LEWF APR 09