Gale Warning 29, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
119 AM AKST TUE FEB 24 2009

.DISCUSSION...

UPPER RIDGE EXTENDING FROM SOUTH CENTRAL ALASKA TO THE MACKENZIE
DELTA REGION AND FARTHER TO THE NORTHEAST WILL MOVE EASTWARD AND
BREAK DOWN DURING THE NEXT 24 TO 36 HOURS AS A SHORT WAVE TROUGH
MOVES EASTWARD ACROSS THE INTERIOR. THIS TROUGH WILL BE FOLLOWED BY
A MINOR RIDGE AND THEN A MUCH STRONGER TROUGH WHICH WILL ARRIVE
WED AFTERNOON OVER THE SOUTHERN PARTS OF THE WEST COAST. THIS
TROUGH WILL WEAKEN AS IT MOVES ACROSS THE INTERIOR LATE WED NIGHT
THROUGH THU.

AN OLD 1004 MB LOW ABOUT 350 NM SOUTHWEST OF SAINT LAWRENCE
ISLAND WILL WEAKEN INTO A TROUGH OVER THE CHUKOTSK PENINSULA
BY 9 PM TUE. A 994 MB LOW ABOUT 1500 NM SOUTHWEST OF SAINT
LAWRENCE ISLAND WILL DEEPEN TO A 984 MB CENTER ABOUT 800 NM
SOUTHWEST OF NUNIVAK ISLAND BY 3 PM TUE...AND MOVE TO THE
YUKON DELTA AS A 986 MB LOW BY 3 PM WED. CURRENT GFS AND NAM
MODEL RUNS ARE IN GOOD AGREEMENT ON FORECAST LOW POSITION
AND CENTRAL PRESSURE. A NEW LOW CENTER MAY DEVELOP OVER
THE CENTRAL ARCTIC COAST BY 3 AM THU THEN MOVE EASTWARD
INTO THE CANADIAN ARCHIPELAGO BY 3 AM FRI.

SIGNIFICANT SNOWFALL AMOUNTS ARE EXPECTED OVER THE SOUTHERN
PARTS OF THE WEST COAST AND WESTERN INTERIOR WED AND WED
NIGHT AS THE STRONGER SHORT WAVE TROUGH AND ITS ASSOCIATED
SURFACE SYSTEM MOVE NORTHEASTWARD.

THE PRECEDING WEAKER SHORT WAVE WILL LIKELY BRING A SHORT
PERIOD OF LIGHT SNOW AS IT MOVES ACROSS THE INTERIOR.

BRISK STRONG EAST TO SOUTHEAST WINDS ARE EXPECTED
TO DEVELOP IN ZONES 211-212-214-WESTERN ZONE 215 WED
MORNING AS THE LOW CENTER APPROACHES TO JUST OFFSHORE
NORTH OF NUNIVAK ISLAND. NORTHWESTERLY GALES ARE EXPECTED
OVER MUCH OF THE WEST COAST WED NIGHT ON THE BACK SIDE OF
THE LOW AS IT MOVES INTO THE INTERIOR...AND BLIZZARD
CONDITIONS ARE POSSIBLE OVER MUCH OF THE WEST COAST...
ESPECIALLY THE SOUTHERN PARTS WHERE THE WINDS WILL PICK
UP AFTER SIGNIFICANT SNOWFALL HAS ALREADY FALLEN. WITH
THE HEAVIEST SNOWFALL AMOUNTS EXPECTED TO OCCUR BEFORE THE
ONSET OF THE STRONG NORTHWESTERLIES...WE HAVE OPTED TO PUT
UP WINTER STORM WATCHES FOR ZONES 212-213-214-215. ZONES
210 AND 211 WILL RECEIVE SNOW ALSO...BUT SNOW AMOUNTS ARE
EXPECTED TO BE LESS THAN 6 INCHES.

SOUTHERLY CHINOOK WINDS ARE EXPECTED IN ALASKA RANGE PASSES
WED THROUGH EARLY THU. ADVISORY LEVEL GUSTS MAY OCCUR AT THE
NORMALLY WINDY SPOTS.

ALONG THE EASTERN ARCTIC COAST...STRONG WEST WINDS MAY
OCCUR THU NIGHT INTO FRI MORNING AFTER A NEW LOW DEVELOPING
OVER THE CENTRAL ARCTIC COAST MOVES EAST...FOLLOWED BY
RAPIDLY BUILDING HIGH PRESSURE.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FOR AKZ212-AKZ213-AKZ214-AKZ215.

BRISK WIND ADVISORY FOR PKZ225-PKZ230-PKZ235.
&&

RF FEB 09