Gale Warning 30, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
300 PM AKST FRI JAN 01 2010

.MODEL DISCUSSION...IN THE SHORT TERM MODELS AGREE ON THE INTENSITY
OF THE UPPER LEVEL RIDGE OVER THE BERING AND THE POTENCY OF THE UPPER
LEVEL ARCTIC LOW. MODELS ALSO CAPTURE THE EMBEDDED SURFACE LOWS IN
THE NORTH PACIFIC TROUGH REGION ADEQUATELY. THERE IS RELATIVE
AGREEMENT ON THE INTENSIFICATION AND PROGRESSION OF A SURFACE LOW
TOWARDS THE CENTRAL ALEUTIAN ISLANDS OVER THE NEXT SEVERAL DAYS. THE
NAM WAS USED FOR THE SOUTHCENTRAL DUE TO ITS HIGHER RESOLUTION AND
DEPICTION OF COOLER AIR FILTERING INTO THE REGION...WHILE A BLEND OF
MODELS WAS USED TO CAPTURE THE PROGRESSION OF LOWS NEAR THE
ALEUTIANS. MODELS BEGIN TO DISAGREE IN THE POSITION OF THIS LOW AND
ASSOCIATED SHORTWAVES BY MONDAY MORNING.

.ANALYSIS AND UPPER LEVELS...AN UPPER LEVEL RIDGE IS STRETCHING FROM
THE WESTERN GULF OF ALASKA INTO THE BERING SEA. A POTENT LOW CENTERED
TO THE NORTHEAST OF MAINLAND ALASKA SPRAWLS ACROSS THE EASTERN
PORTION OF MAINLAND ALASKA. A TROUGH STRETCHES FROM THE WEST JUST
SOUTH OF THE ALEUTIAN ISLANDS. AT THE SURFACE...HIGH PRESSURE BUILDS
INTO MUCH OF MAINLAND ALASKA UNDERNEATH THE UPPER LEVEL RIDGE. A
BROAD TROUGH OF LOW PRESSURE AT THE SURFACE COVERS MUCH OF THE NORTH
PACIFIC WITH SEVERAL EMBEDDED LOWS. A WEAK TROUGH OF LOW PRESSURE
LIES ALONG THE EASTERN COAST OF THE GULF OF ALASKA.

.SHORT TERM FORECAST...
.SOUTH CENTRAL...
DRY WEATHER IS EXPECTED TO PERSIST ACROSS MUCH OF THE SOUTH CENTRAL
REGION FOR THE NEXT SEVERAL DAYS AS HIGH PRESSURE BUILDS AT THE
SURFACE. THE 12Z ANCHORAGE SOUNDING INDICATES A STEEP INVERSION...A
DEEP LAYER OF LIGHT WINDS NEAR THE SURFACE...AND HIGH SURFACE
RELATIVE HUMIDITY. WITH NO EXPECTED CHANGE IN AIRMASS OR STRONGER
SURFACE WINDS...FOG IS EXPECTED TO CONTINUE ACROSS ANCHORAGE THROUGH
THE NIGHT. THE FOG WILL SLOWLY CLEAR OUT SATURDAY AS DRIER AIR
FILTERS INTO THE REGION. THE ADVECTION OF COOLER AND DRIER AIR INTO
THE COPPER RIVER BASIN ALONG WITH INCREASED MIXING WILL HELP TO CLEAR
THE FOG THAT HAS PERSISTED FOR THE PAST SEVERAL DAYS. THE NEXT CHANCE
FOR PRECIPITATION WILL OCCUR LATE SUNDAY NIGHT AS A SURFACE LOW
PRESSURE APPROACHES THE CENTRAL ALEUTIAN ISLANDS AND AN ASSOCIATED
SHORTWAVE PROGRESSES THROUGH THE GULF COAST. SNOW SHOWERS ARE
EXPECTED IN THE ANCHORAGE BOWL MONDAY WHILE RAIN SHOWERS WILL IMPACT
KODIAK ISLAND AND COASTAL REGIONS THROUGH THE MIDDLE OF NEXT WEEK
LIGHT.

.SOUTHWEST...THE CHANCE FOR SHOWERS AND STRONGER WINDS WILL RETURN TO
THE ALASKA PENINSULA BY SATURDAY AS LOW PRESSURE MOVES TOWARDS THE
CENTRAL ALEUTIANS. AN ASSOCIATED SHORTWAVE WILL BRING THE POSSIBILITY
OF PRECIPITATION TO THE INTERIOR OF SOUTHWEST ALASKA BY SUNDAY
EVENING. A SERIES OF SHORTWAVES PROGRESSING AROUND THIS LOW WILL
RESULT IN THE CHANCE OF PRECIPITATION INTO MIDWEEK.

.ALEUTIANS/BERING...GALE FORCE WINDS AND RAIN SHOWERS WILL IMPACT
MUCH OF THE CENTRAL AND EASTERN ALEUTIAN ISLANDS BY SUNDAY AS A NORTH
PACIFIC LOW APPROACHES.

.LONG TERM FORECAST...MODELS INDICATE THAT AN UPPER LEVEL RIDGE WILL
BUILD AGAIN ALONG THE WESTERN COAST OF BRITISH COLUMBIA. SOUTH AND
SOUTHEASTERLY FLOW WILL OCCUR ALONG MUCH OF THE GULF. THIS WILL
RESULT IN A CHANCE OF RAIN ALONG THE COAST THROUGH THE END OF NEXT
WEEK AND A GRADUAL RETURN TO NORMAL AND ABOVE NORMAL TEMPERATURES
THROUGHOUT THE FORECAST AREA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 138 170 172 175 176 179.
         HEAVY FREEZING SPRAY 121 160 180.
FIRE WEATHER...NONE.

JAN 10