Gale Warning 143, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKST SUN FEB 1 2009

.ANALYSIS AND UPPER LEVELS...
A DEEP UPPER LEVEL TROUGH IS PRESENT FROM THE EASTERN BERING EAST
INTO THE MAINLAND. THE BASE OF THE TROUGH...ROUNDED BY THE JET
STREAM...IS WAY DOWN AROUND 35N 160W. A WEAK SYSTEM IS RIDING THE
JET STREAM ON THE EASTERN SIDE OF THE TROUGH...HEADING NORTHEAST
THROUGH THE CENTRAL GULF...AND WILL MAKE LANDFALL AROUND CAPE
SUCKLING THIS EVENING. VERY COLD TEMPERATURES DOMINATE THE MAINLAND
AND EASTERN BERING. WEAK HIGH PRESSURE IS PRESENT IN THE CENTRAL
BERING THIS MORNING. OUT WEST OF THE FORECAST AREA IN THE NORTHWEST
PACIFIC IS A VERY STRONG LOW PRESSURE SYSTEM AND ASSOCIATED FRONT.
THIS FRONT WILL MOVE INTO THE WESTERN ALEUTIANS THIS EVENING.

.MODEL DISCUSSION...
MODELS ARE IN DECENT AGREEMENT OVERALL...BUT THERE ARE SOME ISSUES.
OUT EAST...PREFER THE NAM POSITION ON A WEAK LOW DEVELOPING AROUND
MONTAGUE ISLAND LATE TONIGHT. OUT WEST...THE MODELS ARE IN VERY GOOD
AGREEMENT ON THE TIMING AND STRENGTH OF THE STRONG FRONT MOVING OUT
AHEAD OF THE NORTHWEST PACIFIC LOW. HOWEVER...0Z GFS AND 0Z NAM WERE
NORTHERLY OUTLIERS WITH THE LOW AS IT ENTERS THE SOUTHWEST
BERING...AND WE STAYED CLOSE TO THE PREVIOUS FORECAST FROM THIS TIME
(TUESDAY AFTERNOON) ONWARD WHICH RESEMBLES THE UKMET AND ECMWF
INITIALLY.

.SHORT TERM FORECAST...
SOUTHCENTRAL...
A FAIRLY WEAK LOW PRESSURE SYSTEM MOVING NORTH THROUGH THE GULF WILL
MAKE LANDFALL AROUND CAPE SUCKLING THIS EVENING. THIS SYSTEM WILL
BRING SNOW TODAY AND TONIGHT MAINLY TO THE EASTERN HALF OF THE
COPPER RIVER BASIN AND PERHAPS CORDOVA. AN UPPER LEVEL LOW WILL DIVE
SOUTHEAST FROM NEAR NOME TODAY TO SOUTHCENTRAL ON MONDAY. AS THIS
SYSTEM MOVES DOWN...A NEW SURFACE LOW WILL FORM AROUND MONTAGUE
ISLAND...KEEPING SOME SNOW SHOWERS IN THE PRINCE WILLIAM SOUND AREA.
A LOT OF THE INGREDIENTS LOOK RIGHT FOR SNOW OVER THE COOK INLET
REGION...WITH ONE NOTABLE EXCEPTION BEING MID AND UPPER LEVEL
MOISTURE. STILL...WILL HAVE TO KEEP AN EYE OUT FOR SOME VERY LIGHT
SNOW OVER THE COOK INLET REGION ON MONDAY. STRONG WEST TO NORTHWEST
WINDS WILL BE PRESENT THROUGH MONDAY NIGHT IN THE WESTERN GULF AND
INNER WATERS...WITH THE STRONGEST WINDS BEING THROUGH CHANNELED
TERRAIN. A WEAK RIDGE OF HIGH PRESSURE WILL BUILD IN ON TUESDAY
BEFORE THE NEXT SYSTEM MOVES IN FROM THE SOUTHWEST ON TUESDAY NIGHT
AND WEDNESDAY.

SOUTHWEST MAINLAND...
AN UPPER LEVEL LOW DIVING SOUTHEAST THROUGH THE SOUTHWEST MAINLAND
IN THE SHORT TERM WILL BRING LITTLE IN THE WAY OF PRECIP EXCEPT FOR
A FEW FLURRIES OR AREAS OF VERY LIGHT SNOW...ALONG WITH SOME CLOUDS.
HIGH PRESSURE WILL PERSIST AT THE SURFACE WITH A VERY COLD AIRMASS
IN PLACE. THE COLDEST TEMPERATURES WILL BE IN AREAS WITH LESS
CLOUDCOVER. A WEAKENING FRONT MOVING EAST ACROSS THE BERING WILL
BEGIN TO IMPACT THE SOUTHWEST COAST TUESDAY MORNING.

BERING SEA/ALEUTIANS...
PATTERN CHANGE IN STORE FOR THE BERING/ALEUTIANS WITH COLD NORTHWEST
FLOW BEING REPLACED BY STRONG...WARMER WESTERLY FLOW. A 948 MB
NORTHWEST PACIFIC LOW WILL MOVE TO JUST WEST OF ATTU MONDAY
NIGHT...BUT A STRONG FRONT WILL MOVE WELL OUT AHEAD OF THE LOW. THIS
FRONT WILL REACH THE WESTERN BERING/ALEUTIANS TONIGHT...THE CENTRAL
BERING/ALEUTIANS MONDAY...AND THE EASTERN BERING/ALEUTIANS MONDAY
NIGHT...WEAKENING ALL ALONG. THE FRONT WILL BRING STORM FORCE WINDS
TO THE WESTERN AND CENTRAL ALEUTIANS BEFORE WEAKENING TO GALES. HUGE
SWELLS WILL MOVE IN WITH THIS SYSTEM...WITH SEAS LIKELY TO TOP 40
FEET ESPECIALLY ON THE PACIFIC SIDE OF THE ALEUTIAN CHAIN TUESDAY
AND WEDNESDAY. THE TEMPERATURES APPEAR TO WARM QUICKLY ENOUGH TO
KEEP BLIZZARD CONCERNS AT BAY...WITH THE NOTABLE EXCEPTION OF THE
PRIBILOFS WHERE THINGS COULD GET INTERESTING MONDAY AFTERNOON AND
EVENING.

.LONG TERM FORECAST...
ACTIVE WEST TO SOUTHWEST FLOW WILL PERSIST THROUGH AT LEAST FRIDAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM WARNING ZONES 172 175 176 411 412 413.
         GALE WARNING ZONES 120 130 132 138 155 170 171 179 185 351
          414.
         HEAVY FREEZING SPRAY WARNING ZONES 121 125 129 130 132 138
          140 141 150 155 160 165 179 412 414.
FIRE WEATHER...NONE.

FOISY FEB 09