308
FXAK69 PAFG 202238
AFDAFG
NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
138 PM AKST FRI DEC 20 2024
SYNOPSIS
STRONG NORTHERLY WINDS WILL DEVELOP THIS WEEKEND FROM ST. LAWRENCE
ISLAND THROUGH THE BERING STRAIT. A NUMBER OF LOWS WILL ROTATE
INTO THE SOUTHERN BERING FROM THE GULF OF ALASKA, PAIRED WITH A
SLIGHTLY ANOMALOUS HIGH PRESSURE SITTING OVER FAR EASTERN RUSSIA.
THIS WILL CREATE A PRESSURE GRADIENT THROUGH THE BERING STRAIT.
WINDS GUSTS ASSOCIATED WITH THAT PRESSURE GRADIENT WILL APPROACH
70 MPH. THESE WINDS WILL PERSIST INTO EARLY NEXT WEEK.
DISCUSSION
KEY MESSAGES...
CENTRAL AND EASTERN INTERIOR...
- TANANA VALLEY JET WILL REMAIN ACTIVE THROUGH SATURDAY NIGHT.
WIND GUSTS WILL BE NEAR 45 MPH AT DELTA JUNCTION THROUGH THIS
TIME PERIOD. THEY WILL SLOWLY DIMINISH STARTING SATURDAY
MORNING. SOUTHERLY GAP WINDS IN THE ALASKA RANGE UP TO 45 MPH
WILL PERSIST THROUGH SATURDAY.
- THE DALTON HIGHWAY SUMMITS WILL BEGIN TO SEE INCREASING
NORTHEASTERLY WINDS STARTING OVERNIGHT TONIGHT. WINDS WILL GUST
UP TO 35 TO 40 MPH, AND CAUSE PERIODS OF BLOWING SNOW ALONG THE
DALTON HIGHWAY.
- SUNDAY MORNING, HEAVIER SNOWFALL WILL BEGIN TO DEVELOP IN THE
NORTHEASTERN INTERIOR FROM TANANA TO ARCTIC VILLAGE.
ACCUMULATIONS ON SUNDAY AND MONDAY WILL LOOK TO BE AROUND 4" TO
6". THERE ARE POSSIBILITIES THAT SNOWFALL WILL CONTINUE THROUGH
MUCH OF THE WEEK, BUT THERE IS SIGNIFICANT UNCERTAINTY AS TO
WHERE EXACTLY THE BAND OF HEAVIEST SNOWFALL WILL SET UP.
NORTH SLOPE AND BROOKS RANGE...
- THE WESTERN ARCTIC COASTLINE WILL SEE STRONG NORTHEASTERLY WINDS
OF 60 TO 70 MPH DEVELOP SATURDAY EVENING. THIS WILL BE
PRIMARILY FOCUSED NEAR POINT HOPE AND TO THE SOUTHWEST OFFSHORE.
- ANAKTUVUK AND ATIGUN PASS WILL HAVE 20 TO 25 MPH NORTHERLY
WINDS DEVELOP SUNDAY MORNING AND LAST THROUGH THE DAY. THE
WESTERN BROOKS RANGE WILL HAVE GUSTY NORTHEASTERLY WINDS UP TO
45 MPH THIS WEEKEND.
WEST COAST AND WESTERN INTERIOR...
- GALE FORCE NORTHERLY WINDS WILL DEVELOP OVERNIGHT TONIGHT. THE
STRONGEST CORE OF WINDS WILL BE FROM ST. LAWRENCE ISLAND TO THE
BERING STRAIT. WIND GUSTS UP TO 70 MPH ARE EXPECTED AND A SMALL
CHANCE TO SEE GUSTS UP TO 75 TO 80 MPH. WINDS WILL LINGER AT ST.
LAWRENCE ISLAND THROUGH THE MIDDLE PORTION OF THE WEEK, HOWEVER
THEY WILL BE WEAKER WITH GUSTS UP TO 50 MPH EXPECTED.
- WITH STRONG NORTHERLY WINDS WE WILL SEE RAPID ICE GROWTH FROM
THE BERING STRAIT TO ST. LAWRENCE ISLAND. WITH OPEN WATER STILL
TO THE NORTH OF SAVOONGA THERE COULD BE SOME SMALL FREEZING
SPRAY CONCERNS IN TOWN. TEMPERATURES WILL STILL BE 10 TO 20
DEGREES ABOVE 0, THAT WILL HELP TO MINIMIZE THE FREEZING SPRAY
CONCERNS.
- EASTERN NORTON SOUND AND THE Y-K DELTA COASTLINE WILL SEE
NORTHEASTERLY WINDS OF 35 TO 45 MPH THROUGH THE WEEKEND.
ANALYSIS AND FORECAST CONFIDENCE...
A BROAD AREA OF HIGH PRESSURE REMAINS OVER FAR EASTERN RUSSIA.
THIS WILL BEGIN TO MOVE TO THE SOUTHWEST AS THE LOW NORTH OF THE
CANADIAN BECOMES MORE DOMINANT. A LOW PRESSURE OFF THE COAST OF
DEADHORSE WILL CONTINUE TO WEAKEN THROUGH TONIGHT, AND WILL GET
SUCKED INTO THE LONGWAVE TROUGH AS A WEAK WAVE. A CONGLOMERATE OF
LOWS WILL CONTINUE TO ROTATE INTO THE BERING SEA FROM THE GULF OF
ALASKA.
AT THE SURFACE A 968 MB LOW JUST NORTH OF COLD BAY IN THE BERING
SEA AND A 1022 MB HIGH IN SIBERIA, WILL CREATE A 40 MB PRESSURE
GRADIENT IN THE BERING STRAIT BY SUNDAY MORNING. THE ECMWF
ENSEMBLE STANDARDIZED ANOMALIES FOR SURFACE WIND SPEEDS IS AROUND
1.5 TO 2.5 STANDARD DEVIATIONS FROM THE MEAN. THESE ANOMALIES WILL
CONTINUE THROUGH WEDNESDAY CENTERED AROUND ST. LAWRENCE ISLAND.
LOOKING INTO THE SNOW CHANCES FOR HEAVIER SNOWFALL NEXT WEEK.
THERE IS NOT A LOT OF CONFIDENCE IN THE TIMING AND EXACT LOCATION,
BUT MODERATE CONFIDENCE THAT THERE WILL BE SNOW. AS THE ARCTIC
TROUGH DIGS DOWN THROUGH THE STATE, A DEFORMATION BAND WILL LIKELY
SET UP. THE LOCATION OF THE BAND WILL BE DETERMINED ON THE SPEED
OF THE TROUGH AS WELL AS THE SPEED OF A LOW COMING ACROSS THE
ALASKA RANGE. AT 700MB THE GFS, ECMWF, AND THE CANADIAN ARE
BRINGING A TROUGH INTO THE INTERIOR PORTIONS OF THE STATE. THIS
WOULD BE ACCOMPANIED WITH EMBEDDED LOWS IN THAT TROUGH. WITH
SOUTHWESTERLY FLOW BEING BROUGHT INTO THE INTERIOR, THERE WOULD BE
SUFFICIENT MOISTURE ADVECTION TO HELP SUPPORT HIGHER QPF VALUES
AND THEN THEREFORE HIGHER SNOW TOTALS. THIS EVENT WOULD BE A
MULTI-DAY SNOW EVENT. THERE ARE A LOT OF MOVING PARTS AS OUR
PATTERN IS VERY COMPLEX RIGHT NOW. CONFIDENCE SHOULD BE IMPROVED
AS THE HIGH PRESSURE IN THE SIBERIA MOVES TO THE SOUTHWEST.
EXTENDED FORECAST DAYS 4-7...
SUNDAY NIGHT AN ARCTIC FRONT ASSOCIATED WITH A LOW PRESSURE DIG
INTO THE CANADIAN WILL BEGIN TO STRENGTHEN. AT 500 MB WE WILL
SEE THE LONGWAVE TROUGH ASSOCIATED WITH THAT LOW BEGIN TO BECOME
POSITIVELY TILTED. THIS TROUGH WILL HELP TO DEVELOP THE HEAVY
SNOWFALL POTENTIAL FROM THE Y-K DELTA TO THE YUKON FLATS. BY
TUESDAY WE WILL HAVE A REINFORCING LOW COME OVER THE ALASKA RANGE
AND HELP TO STRENGTHEN THAT TROUGH. THE TIMING OF WHEN THESE
FEATURES MEET IS VERY UNCERTAIN. IF IT'S QUICKER THEN THE HEAVIEST
BAND OF SNOW WILL BE TO THE SOUTH AND IF IT'S SLOWER THEN IT WILL
BE FARTHER NORTH. THERE WILL BE HEAVY SNOWFALL IN THE INTERIOR
NEXT WEEK, BUT THE EXACT TIMING AND PLACEMENT IS STILL VERY
UNCERTAIN. WHEN THE ARCTIC FRONT PASSES, EXPECT COLD ARCTIC AIR
RUSH INTO MUCH OF THE INTERIOR. THE COLDEST SPOTS ARE LOOKING TO
BE WEST OF TANANA, WITH LOWS IN THE 20S TO 30S BELOW.
COASTAL HAZARD POTENTIAL...
WITH GALE FORCE NORTHERLY WINDS, COASTAL EROSION WILL BE THE
PRIMARY CONCERN. WE COULD SEE ICE NEAR THE SHORELINE BREAKOFF FROM
THE MAIN ICEPACK AND MOVE AROUND. ICE SHOVES SHOULD NOT BE A
CONCERN.
AFG WATCHES/WARNINGS/ADVISORIES
AK...HIGH WIND WARNING FOR AKZ801.
WINTER WEATHER ADVISORY FOR AKZ815-816-832.
HIGH WIND WARNING FOR AKZ820-821.
HIGH WIND WARNING FOR AKZ827.
PK...HEAVY FREEZING SPRAY WARNING FOR PKZ801-807-816-817-851-854.
SMALL CRAFT ADVISORY FOR PKZ801.
BRISK WIND ADVISORY FOR PKZ802>806-810-850-852-853.
GALE WARNING FOR PKZ811-856-857.
BRISK WIND ADVISORY FOR PKZ812-858.
GALE WARNING FOR PKZ816-817-851-854.
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