Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 202121
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
121 PM AKDT SAT SEP 20 2014

.DISCUSSION...

MODELS...GOOD RUN TO RUN CONTINUITY FOR THE SHORT TERM AND THEY
CONTINUE TO INITIALIZE WELL. BEYOND 60 HOURS THERE ARE PRETTY
LARGE DISCREPANCIES IN THE STRENGTH AND MOVEMENT OF THE UPPER
LEVEL LOW OVER THE CHUKCHI SEA...BUT THEY ARE HANDLING THE
ASSOCIATED TROUGH SIMILARLY IN ITS MOVEMENT. THERE ARE ALSO LARGE
DIFFERENCES IN THE HANDLING OF THE RIDGE BUILDING OVER BRISTOL
BAY AND THE EASTERN BERING SEA. SHORT TERM WILL USE A NUDGE TO A
MODEL BLEND...IN THE MIDRANGE AND BEYOND WILL USE A BLEND OF THE
MODELS WITH A NUDGE TO WPC GUIDANCE.

ALOFT...AT 500 HPA...530 DAM CLOSED LOW OVER POINT LAY WITH
ASSOCIATED TROUGH EXTENDING SOUTH TO MCGRATH WILL MOVE SOUTHEAST
TO OVER ANAKTUVUK PASS BY SUNDAY MORNING WITH THE TROUGH
EXTENDING SOUTH OVER WESTERN COOK INLET. THE LOW WEAKENS AND
MOVES NORTHEAST WITH THE TROUGH MOVING TO LIE FROM OVER KUPARUK
TO FORT YUKON TO DELTA JUNCTION AND SOUTH TO A 535 DAM CLOSED LOW
OVER THE GULF OF ALASKA. A 556 DAM RIDGE OVER THE EASTERN BERING
SEA AND SOUTHERN CHUKCHI SEA WILL ROTATE TO THE SOUTHEAST TO LIE
FROM OVER DUTCH HARBOR TO HUSLIA TO NUIQSUT BY MONDAY MORNING THEN
CONTINUE TO ROTATE AS IT WEAKENS TO LIE FROM THE NORTH PACIFIC TO
TALKEETNA TO FORT YUKON TO MACKENZIE BAY BY TUESDAY MORNING BEFORE
ROTATING OUT OF THE AREA. A 526 DAM LOW NEAR 74N 130E WILL MOVE TO
NEAR WRANGEL ISLAND SUNDAY EVENING...THEN CONTINUE TO THE VICINITY
OF THE NORTHWEST COAST BY MONDAY EVENING...THEN CONTINUE TO MOVE
EAST ACROSS THE ARCTIC THROUGH MIDWEEK. A 540 DAM LOW OVER 52N
150W WILL SWING OVER THE NORTHEAST GULF OF ALASKA BY SUNDAY NIGHT
AS HEIGHTS FALL TO 528 DAM...THEN MERGES WITH THE LONG WAVE TROUGH
MOVING ACROSS THE AREA. AT 850 HPA...ZERO ISOTHERM LIES FROM
BARTER ISLAND TO ARCTIC VILLAGE TO TANANA TO SLEETMUTE AND
SOUTHWEST TODAY AND WILL LIE FROM MACKENZIE BAY TO FORT YUKON TO
DELTA JUNCTION THEN SOUTHWEST BY SUNDAY EVENING WITH TEMPERATURES
AS LOW AS MINUS 9 CELSIUS OVER THE ARCTIC COAST.

SURFACE...A BROAD AREA OF LOW PRESSURE OVER THE INTERIOR CENTERED
OVER THE UPPER YUKON FLATS IS SLOWLY WORKING ITS WAY EAST IN
ADVANCE OF THE UPPER LEVEL TROUGH. RIDGE IS BUILDING OVER THE
WEST COAST WITH A 1015MB CENTER OVER THE BERING STRAIT TONIGHT.
AS THE UPPER LEVEL TROUGH MOVES EAST THE RIDGE PUSHES INTO THE
MIDDLE YUKON VALLEY TONIGHT. A 989MB LOW IN THE SOUTHEAST GULF OF
ALASKA WILL MOVE TO THE NORTHEAST GULF BY SUNDAY AFTERNOON AND TO
PRINCE WILLIAM SOUND BY MONDAY MORNING. A 1005MB LOW OVER EASTERN
SIBERIA SUNDAY MORNING WILL MOVE TO THE NORTHWEST ARCTIC COAST BY
MONDAY MORNING AND TO NEAR BARROW BY TUESDAY MORNING THEN
CONTINUE EAST.

ARCTIC COAST AND PLAIN...THE MESSY MIX OF LOW CLOUDS...FOG...SNOW
...RAIN...WIND...AND COOLING TEMPERATURES OVER THE ARCTIC COAST
CONTINUES. THE GOES MVFR PROBABILITY 4KM AT 20/1900Z SHOWS HIGH
PROBABILITY OF MVFR OVER VAST AREAS OF THE STATE AND OFFSHORE
AREAS. SOME PATCHY AREAS OF IFR SHOWING UP ON THAT PRODUCT BUT
NOTHING SUBSTANTIAL. THE NPP VIIRS DAY NIGHT BAND AT 20/1718Z
CONFIRMS CLOUD COVER OVER THE AREA AND SHOWS A NICE CLEAR TO
PARTLY CLOUDY AREA OVER THE NORTHEAST ARCTIC OFFSHORE AREA. THE
TIGHTEST GRADIENT HAS MOVED OVER THE NORTHEAST OFFSHORE WATERS SO
WINDS ALONG THE COAST ARE DOWN SIGNIFICANTLY FOR THE TIME
BEING...BUT LOOK FOR THEM TO COME BACK UP AS LATEST MODELS ARE
DEVELOPING A LOW OVER THE CENTRAL ARCTIC COAST TONIGHT WHICH WILL
BRING SOME STRONG GUSTY WINDS OF 10 TO 20 MPH GUSTING TO 35 MPH
TO AREAS WEST OF DEADHORSE...WITH SOUTHEAST TO SOUTHWEST WINDS 5
TO 15 MPH FROM DEADHORSE EAST.

WEST COAST AND WESTERN INTERIOR...COASTAL AREAS REMAIN PRETTY
NICE...BUT LOOK FOR SOME PATCHY STRATUS TO MOVE OVER THE AREA AS
COOL AIR MOVES SOUTH OVER THE WARMER WATER. NPP VIIRS DAY NIGHT
BAND SAT AT 20/1700Z SHOWS A PRETTY GOOD CLEARING LINE ASSOCIATED
WITH THE UPPER TROUGH THAT LIES FROM AMBLER TO BETHEL SO EXPECT
CLEARING IN THE INLAND AREAS AS THAT WORKS EAST. RAINFALL WILL
ALSO BE ENDING AS THINGS CLEAR OUT. SOME PATCHY FOG ALONG THE
RIVER SUNDAY MORNING...BUT DO NOT EXPECT ANY SIGNIFICANT PERIOD
OF DENSE FOG. WINDS GENERALLY LIGHT THROUGH TUESDAY. INLAND AREAS
WILL CONTINUE TO SEE TEMPERATURES COOL...WHILE COASTAL AREAS WILL
BE MODERATED BY THE OPEN WATER.

INTERIOR...RAIN PERSISTING OVER MUCH OF THE INTERIOR THROUGH THE
NIGHT...BECOMING PATCHY BY LATE SUNDAY MORNING...THEN ENDING IN
MOST AREAS BY MID DAY SUNDAY. A SOUTHEAST WAVE WILL SWING UP
OVER THE FORTYMILE COUNTRY SUNDAY NIGHT AND POTENTIALLY MAKE IT
AS FAR WEST AS THE FAIRBANKS AREA EARLY MONDAY. NOT EXPECTING
MUCH PRECIPITATION WEST OF DELTA JUNCTION WITH THIS...AND THE
HEAVIEST RAINFALL WILL BE IN THE FORTYMILE COUNTRY. RAIN FALL
AMOUNTS THROUGH  SUNDAY AFTERNOON WILL BE LESS THAN ONE HALF
INCH...AND RAINFALL AMOUNTS OVER THE FORTYMILE COUNTRY WILL BE
BETWEEN ONE QUARTER AND ONE HALF INCH. THE UNEXPECTED WINDS IN
THE ALASKA RANGE LAST NIGHT HAVE TAPERED DOWN TO 10 TO 20 MPH AND
STILL A LITTLE GUSTY...BUT EXPECT THEM TO CONTINUE TO DROP OFF
TONIGHT...THEN JUST LIGHT WINDS OVER THE AREA SUNDAY AND MONDAY.
SLIGHT CHANCE FOR A FEW SNOWFLAKES AT HIGHER ELEVATION IN THE
INTERIOR AS THAT COLD AIR PUSHES SOUTH...BUT NOT EXPECTING ANY
SIGNIFICANT ACCUMULATION.

&&

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE.

&&

.HYDROLOGY...NO SIGNIFICANT RISES EXPECTED WITH THIS RAIN EVENT.

&&

.FIRE WEATHER...NONE.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...

SMALL CRAFT ADVISORY FOR PKZ235.

GALE WARNING FOR PKZ240-PKZ245.

HEAVY FREEZING SPRAY FOR PKZ510.

&&

$$

SDB SEP 14


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