Area Forecast Discussion
Issued by NWS Fairbanks, AK

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296
FXAK69 PAFG 192313
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
213 PM AKST FRI DEC 19 2014

.DISCUSSION...

FAIRLY QUIET WEATHER PATTERN WILL PERSIST OVER NORTHERN ALASKA
THROUGH THE NEXT 60 HOURS. THERE ARE A FEW FORECAST HIGHLIGHTS
INCLUDING STRATUS OVER PARTS OF THE INTERIOR...ELEVATED WINDS OVER
PORTIONS OF THE INTERIOR...ARCTIC COAST...AND WEST COAST...AND
COLD AIR ADVECTION COMMENCING OVER THE WEST COAST/WESTERN INTERIOR
STARTING EARLY MONDAY MORNING.

12Z DETERMINISTIC MODEL SUITE IN GOOD AGREEMENT THROUGH THE FIRST
80 HOURS...BEFORE DIFFERENCES IN MODEL SOLUTIONS IN THE
AMPLITUDE...STRENGTH...AND POSITIONING OF SYNOPTIC FEATURES BECOME
APPARENT DURING THE LONG RANGE. EVEN THOUGH THERE IS GOOD
AGREEMENT BETWEEN MODEL SOLUTIONS REGARDING THE OVERALL SYNOPTIC
PATTERN AND PLACEMENT...THERE ARE SOME SUBTLE DIFFERENCES IN THE
STRENGTH OF FEATURES. A BLEND OF MODEL SOLUTIONS WAS USED FOR THIS
FORECAST PACKAGE.

ALOFT...EAST-WEST ORIENTED RIDGE OVER MAINLAND ALASKA WILL SHIFT
NORTH THROUGH THE WEEKEND AND BECOME MORE NORTHWEST TO SOUTHEAST
ORIENTED OVER EASTERN ALASKA/BEAUFORT SEA/ARCTIC OCEAN BY 00Z
MONDAY. BROAD LOW STRETCHING ALONG THE EASTERN ALEUTIANS AND
ALASKA PENINSULA WILL ROTATE NORTHWARD AND OVER THE WESTERN TWO
THIRDS OF MAINLAND ALASKA BY 00Z. A WEAK SHORTWAVE FROM SIBERIA
WILL MOVE EAST AND TO THE BERING STRAIT BY 18Z SUNDAY.

MODELS ARE HINTING AT A COOLING TREND FOR MOST OF NORTHERN ALASKA
BEGINNING LATE THIS WEEKEND. COINCIDENT WITH THE SHORTWAVE FROM
SIBERIA...COLDER H850 TEMPERATURES WILL ADVECT SOUTHEAST AND OVER
MOST OF NORTHERN ALASKA AND WILL BE MOST EVIDENT ACROSS THE WEST
COAST AND NORTH SLOPE. THERE ARE SOME DIFFERENCES BETWEEN THE 12Z
MODELS...THE GFS IS MORE PROGRESSIVE WITH MOVING THE COLDER H850
TEMPERATURES EASTWARD INTO THE EASTERN INTERIOR. HOWEVER...BOTH
THE NAM AND ECWMF CONTAIN THE COLDEST AIR TO THE WEST AND LIMIT
THE EASTWARD PROGRESSION TO CENTRAL INTERIOR. BOTH THESE MODELS
ARE DEPICTING SOUTHERLY FLOW/CHINOOK PATTERN DEVELOPING...KEEPING
THE H850 TEMPERATURES WARMER OVER THE EASTERN INTERIOR.

SURFACE...964 MB LOW NEAR ATKA WILL MOVE SOUTHEAST AND
WEAKEN...BECOMING A PART OF AN EAST TO WEST ELONGATED LOW COMPLEX
OVER THE ALASKA GULF BY 18Z SATURDAY. BY 18Z SUNDAY...IT WILL
SHIFT NORTHEAST AND OVER SOUTHERN ALASKA BECOMING SOUTHWEST TO
NORTHEAST ORIENTED. THEREAFTER...GENERAL MODEL CONSENSUS PAINTS A
BROAD LOW PRESSURE OVER MAINLAND ALASKA.

SUCCESSIVE SURFACE ANALYSES HAVE SHOWN THE GRADIENT NORTH OF THE
ALASKA RANGE INCREASING. WINDS OVER INTERIOR HILLS AND SUMMITS
HAVE INCREASED OVER INTERIOR HILLS AND SUMMITS THIS MORNING...WITH
THE USUAL SUSPECTS...FOR EXAMPLE INDIAN MOUNTAIN...GUSTING UP TO
30 MPH. EXPECTING WINDS TO REMAIN UP THROUGH THE WEEKEND BEFORE
GRADUALLY DIMINISHING. IN THE INTERIOR VALLEYS...WINDS HAVE BEEN
GENERALLY LIGHT. THE TANANA VALLEY JET PERSISTS...WITH DELTA
JUNCTION REPORTING GUSTS AROUND 30 MPH. EXPECTING THAT IT WILL
CONTINUE OVERNIGHT AND TOMORROW...THEN SUBSIDE TOMORROW NIGHT AS
DEPICTED BY THE 12Z NAM.

THE LATEST MODIS/NPP VIIRS MICROPHYSICS RGB IMAGE DEPICTS AN AREA
OF STRATUS OVER THE YUKON FLATS AND AN EXTENSIVE AREA OVER WESTERN
CANADA ALONG THE NORTHEASTERN AK/YUKON BORDER. FROM THIS
MORNING...THE STRATUS CLOUD DECK HAS SHRUNK BUT IS STILL PRESENT.
THE TREND WILL CONTINUE...WITH THE REMNANT STRATUS DECK ERODING
OVERNIGHT IN THE YUKON FLATS.

OVERALL...DRY AND WARM PATTERN WILL CONTINUE THROUGH THE WEEKEND
FOR MOST OF NORTHERN ALASKA. THE EXCEPTION WILL BE AREAS OF
SCATTERED SNOW SHOWERS AND FOG ALONG THE ARCTIC COAST...THE UPPER
TANANA VALLEY AND THE BERING STRAIT/ST LAWRENCE ISLAND.


COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HEAVY FREEZING SPRAY WARNING FOR PKZ210.

SMALL CRAFT ADVISORY FOR PKZ210.

BRISK WIND ADVISORY FOR PKZ220-PKZ225-PKZ230-PKZ240-PKZ245.
&&

$$

LTH DEC 14



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