High Wind in Alaska, December 3, 2009

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
257 AM AKST THU DEC 3 2009

.DISCUSSION...
WINDS HAVE SPIKED UP RAPIDLY AT BARTER ISLAND LATE WED
EVENING WITH THE DEVELOPMENT OF A 990 MB LOW WHICH IS NOW
NORTHEAST OF BARTER ISLAND. WESTERLIES GUSTING TO 50 MPH
WILL CONTINUE THROUGH THU THEN DIMINISH THU NIGHT. WINTER
WEATHER ADVISORY FOR AKZ204 WILL RUN THROUGH 6 PM THU.

BRISK NORTH WINDS REMAIN IN PROGRESS OVER ST LAWRENCE ISLAND
AND THE BERING STRAIT WITH PERSISTENT TIGHT PINCH IN THE SEA
LEVEL PRESSURE FIELD OVER THOSE AREAS. THE PRESSURE GRADIENT
IS EXPECTED TO RELAX RAPIDLY TODAY AS THE 992 MB LOW CENTER
OVER NORTON SOUND FILLS. WILL EXTEND THE WINTER WEATHER ADVISORY
FOR AKZ213 THROUGH NOON THU. WINDS OVER SAINT LAWRENCE ISLAND
AND THE BERING STRAIT WILL DIMINISH THU AFTERNOON AND EVENING.

EAST WINDS WILL BEGIN TO INCREASE OVER ST LAWRENCE ISLAND/NORTON
SOUND/WEST COAST ZONES SOUTH OF NORTON SOUND FRI AS THE FIRST
OF TWO DEEP SYSTEMS MOVES NORTHWESTWARD TO SOUTH OF ADAK.
BY LATE FRI NIGHT...EASTERLY GALE TO STORM FORCE WINDS SPREADING
TO SOUTHERN PARTS PKZ210...EASTERLY GALES DEVELOPING OVER
NORTON SOUND...SOUTHEASTERLY GALES OR GALE GUSTS DEVELOPING
AKZ214-SW PARTS AKZ212/AKZ215. CURRENT GFS/NAM RUNS IN AGREEMENT
ON THE FORECAST FOR THE FIRST SYSTEM AND ASSOCIATED PRESSURE
GRADIENTS OVER THE NORTHERN BERING.

A SECOND DEEP SYSTEM IS EXPECTED TO DEVELOP RAPIDLY LATE
FRI NIGHT AS IT APPROACHES THE ALEUTIAN CHAIN WEST OF DUTCH
HARBOR...BECOMING THE DOMINANT SYSTEM. EAST TO SOUTHEAST
GALE TO STORM FORCE WINDS CONTINUING SAT OVER PKZ210/AKZ213.
SOUTHEAST GALES OR GALE GUSTS CONTINUING THROUGH SAT OVER
NORTON SOUND/AKZ214/SW PARTS AKZ212/AKZ215. EAST TO SOUTHEAST
GALES DEVELOPING IN AKZ209/PKZ215 SAT. WINTER STORM WATCHES
WILL BE POSTED ON THIS ROUND FOR AKZ211/AKZ213/AKZ215 BEGINNING
FRI EVENING.

TEMPERATURES OVER SAINT LAWRENCE ISLAND/AKZ214 LIKELY
TO RISE TO NEAR OR ABOVE FREEZING BY SAT MORNING. NEAR
OR POSSIBLY SLIGHTLY ABOVE FREEZING TEMPERATURES SPREADING
TO PARTS OF AKZ212/AKZ215/AKZ211 BY FRI EVE. THUS SEVERAL
PRECIPITATION TYPES LIKELY WITH THIS EVENT INCLUDING POSSIBLE
FREEZING RAIN.

SOUTHERLY GAP WINDS EXPECTED TO DEVELOP IN ALASKA RANGE
PASSES FRI NIGHT CONTINUING INTO SUN.

STRONG UPPER LEVEL HIGH IS PROGGED BY ALL MODELS TO DEVELOP
OVER THE EASTERN NORTH GULF COAST/NORTHWEST PANHANDLE BY SUN
AFTERNOON. GFS/ECMWF SOLUTIONS DIVERGE RAPIDLY THROUGH EARLY
NEXT WEEK...GFS MOVING THE UPPER HIGH RAPIDLY NORTHWESTWARD INTO
CENTRAL RUSSIA BY MID WEEK AS NORTHERLY FLOW AND THE FRINGE OF A
VERY COLD AIR MASS MOVES TO THE EASTERN PARTS OF THE FORECAST AREA.
ECMWF HOLDING THE UPPER HIGH MUCH FARTHER TO THE EAST...OVER SOUTHWEST
AK AND THE NORTHERN BERING...WHILE KEEPING THE DEEP COLD AIR MUCH
FARTHER TO THE EAST...OVER NORTHWEST CANADA. THE EASTERN SECTIONS OF
THE FORECAST AREA WILL UNDOUBTEDLY EXPERIENCE SOME COOLING BY LATER
IN THE WEEK...BUT THE AMOUNT OF COOLING IS STILL UNCERTAIN
AT THIS TIME. YESTERDAYS HPC DISCUSSION INDICATING THE ENSEMBLE
MEANS FROM THE 00Z WED ECMWF RUN ARE SHOWING MORE COOLING OVER THE
EASTERN PARTS OF AK THAN SUGGESTED BY THE OPERATIONAL RUN.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FOR AKZ204-AKZ213.

WINTER STORM WATCH FOR AKZ211-AKZ213-AKZ214.

HEAVY FREEZING SPRAY WARNING FOR PKZ210.

SMALL CRAFT ADVISORY FOR PKZ210.

BRISK WIND ADVISORY FOR PKZ220-PKZ225-PKZ240-PKZ245.
&&

RF DEC 09