225
FXAK69 PAFG 222118
AFDAFG
NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
118 PM AKDT MON OCT 22 2018
DISCUSSION
THE NEXT ROUND OF WINTER WEATHER OVER INTERIOR ALASKA AND NORTH
SLOPE WILL BE THE MAIN FORECAST CONCERN FOR THE NEXT COUPLE OF
DAYS. A FAIRLY ACTIVE PATTERN WILL CONTINUE ACROSS NORTHERN ALASKA
THIS WEEK INTO THE WEEKEND AS MULTIPLE LOWS MOVE INTO THE GULF OF
ALASKA AND THEN INTO INTERIOR ALASKA. LATEST MODEL SOLUTIONS ARE
IN FAIR AGREEMENT THROUGH THE FORECAST PERIOD REGARDING THE
OVERALL SYNOPTIC PATTERN; HOWEVER THERE ARE SOME DISCREPANCIES
WITH THE STRENGTH OF INDIVIDUAL LOWS OVER THE GULF OF ALASKA.
ALOFT, AT 500 MB, A LONGWAVE TROUGH CURRENTLY OVER THE BERING SEA
AND MAINLAND ALASKA WILL GENERALLY REMAIN IN PLACE THIS WEEK AS
SEVERAL FEATURE MOVE WITHIN THE TROUGH. A STRONG SHORTWAVE
CURRENTLY IN THE WESTERN GULF OF ALASKA WILL RAPIDLY DEEPEN THIS
EVENING AND TONIGHT INTO A 523 DAM LOW OVER PRINCE WILLIAM SOUND
BY TOMORROW MORNING. THIS LOW WILL MOVE NORTH INTO THE
SOUTHWESTERN INTERIOR BY TUESDAY EVENING. A 525 DAM LOW CURRENTLY
OVER THE PRIBILOFS WILL DEEPEN TO A 519 DAM LOW OVER SAND POINT BY
TUESDAY AFTERNOON WITH ANOTHER 520 DAM LOW OVER UNALASKA. THESE
TWO WILL MERGE TOGETHER TUESDAY EVENING AND MOVE INTO THE WESTERN
GULF OF ALASKA BY WEDNESDAY EVENING. A 525 DAM LOW WILL EMERGE
FROM THE NORTHERN PACIFIC OCEAN WEDNESDAY MORNING AND THEN MOVE
NORTH INTO THE GULF OF ALASKA TO BE 200 MILES SOUTH OF PRINCE
WILLIAM SOUND THURSDAY AFTERNOON.
AT THE SURFACE, A CONGLOMERATION OF MULTIPLE LOW CENTERS
CURRENTLY OVER THE GULF OF ALASKA WILL MERGE WITH A 985 MB LOW
THAT WILL EMERGE FROM THE NORTHEAST PACIFIC THIS EVENING. THIS 985
MB LOW WILL RAPIDLY DEEPEN AS IT TRAVELS NORTH INTO THE GULF OF
ALASKA TONIGHT AND WILL BECOME A 969 MB LOW 100 TO 150 MILES SOUTH
OF PRINCE WILLIAM SOUND BY TOMORROW MORNING. MODEL DISAGREEMENT
REGARDING THIS LOW REMAIN, ESPECIALLY WITH THE STRENGTH OF THE
LOW. THE ECMWF IS ABOUT 10 MB STRONGER THAN BOTH THE NAM AND GFS
TOMORROW MORNING BEFORE THE LOW MOVES INLAND OVER SOUTHCENTRAL
ALASKA. ITS ATTENDANT FRONT WILL MOVE NORTH OVER THE EASTERN
ALASKA RANGE TOMORROW MORNING, THEN OVER THE EASTERN INTERIOR
TOMORROW REACHING THE BROOKS RANGE BY LATE TUESDAY NIGHT. A 990 MB
LOW CENTERED SOUTH OF NUNIVAK ISLAND WILL MOVE SOUTH OVER THE
CENTRAL ALEUTIANS AND WEAKEN THROUGH WEDNESDAY. BY TOMORROW
EVENING, ANOTHER STRONG LOW WILL MOVE NORTH INTO THE SOUTHERN GULF
OF ALASKA BY THURSDAY MORNING AND THEN CONTINUE NORTH TO BE 150
MILES SOUTH OF PRINCE WILLIAM SOUND FRIDAY MORNING.
EASTERN AND CENTRAL INTERIOR...THE NEXT ROUND OF MESSY WINTER WEATHER
WILL BE THE MAIN FOCUS OVER THE NEXT COUPLE OF DAYS, ESPECIALLY
WITH TIMING AND PRECIPITATION TYPE. WITH THE LATEST ROUND OF
GUIDANCE, IT LOOKS LIKE SNOW WILL DEVELOP OVER THE UPPER TANANA
VALLEY EARLY TOMORROW MORNING AND SHIFT NORTH TO BE OVER FAIRBANKS
TO CENTRAL AROUND NOON, THEN CONTINUE NORTH REACHING THE
SOUTHEASTERN BROOKS RANGE BY MIDNIGHT TUESDAY. OVER THE SOUTHERN
INTERIOR, PRECIPITATION WILL BE SHORT LIVED AND WILL BE INITIALLY
SNOW AND WILL CHANGE OVER THE A RAIN/SNOW (POSSIBLY FREEZING
RAIN) MIX LATE IN THE AFTERNOON BEFORE TAPERING OFF DURING THE
EVENING. OVER THE NORTHERN INTERIOR, SNOW WILL PILE UP AGAINST THE
SOUTHERN SLOPES AND FOOTHILLS OF THE BROOKS RANGE TUESDAY NIGHT
INTO WEDNESDAY MORNING BEFORE TAPERING OFF TO SHOWERS LATER
WEDNESDAY. THE HIGHEST SNOWFALL AMOUNTS ARE EXPECTED FROM
LIVENGOOD TO CENTRAL NORTH, WHERE 2 TO 4 INCHES ARE EXPECTED AND
TO THE SOUTH UP TO 2 INCHES ARE EXPECTED THROUGH WEDNESDAY
AFTERNOON. IN VALLEY LOCATIONS SUCH AS FAIRBANKS AND NORTH POLE,
SNOW AMOUNTS WILL BE NEGLIGIBLE DUE TO RAIN MIXING IN WITH SNOW.
SOUTHERLY FLOW OVER THE EASTERN ALASKA RANGE WILL DEVELOP TUESDAY
NIGHT AND CONTINUE INTO WEDNESDAY WHERE SOUTH GAP WINDS MAY FLIRT
WITH ADVISORY CRITERIA. MAY ALSO SEE GUSTY EAST TO NORTHEAST WINDS
OVER HILLS AND HIGHWAY SUMMITS TUESDAY AND TUESDAY NIGHT WITH
SUSTAINED VALUES AROUND 15 TO 25 MPH WITH GUSTS TO AROUND 35 MPH
POSSIBLE. NEXT ROUND OF PRECIPITATION WILL COME FRIDAY WHEN
ANOTHER FRONT MOVES NORTH FROM THE GULF OF ALASKA.
WEST COAST AND WESTERN INTERIOR...ISOLATED TO SCATTERED SHOWERS
OVER NORTON SOUND AND YUKON DELTA WILL TAPER OFF THIS EVENING.
NORTHEAST WINDS OVER THE BERING SEA, BERING STRAIT, AND CHUKCHI
SEA WILL CONTINUE THROUGH LATE TOMORROW AND THEN INCREASE TUESDAY
NIGHT TO GALE FORCE SUSTAINED WINDS WHICH WILL CONTINUE INTO
WEDNESDAY AND THURSDAY. SNOW WILL DEVELOP OVER THE WESTERN
INTERIOR TOMORROW AFTERNOON AND WILL CONTINUE INTO LATE WEDNESDAY
AS SHOWERS WITH 1 TO 2 INCHES OF SNOW ACCUMULATION EXPECTED. THERE
IS THE POTENTIAL TO SEE FREEZING RAIN OR RAIN MIX IN OVER VALLEY
LOCATIONS INITIALLY AS THE PRECIP DEVELOPS AND AGAIN LATE
MORNING/EARLY AFTERNOON WEDNESDAY. ELSEWHERE, SNOW SHOWERS ARE
EXPECTED OVER THE NORTHWEST AND CHUKCHI SEA COASTAL LOCATIONS WITH
NEGLIGIBLE SNOW ACCUMULATIONS EXPECTED AND RAIN SHOWERS OVER THE
BERING SEA AND NORTON SOUND.
NORTH SLOPE AND BROOKS RANGE...SNOW ASSOCIATED WITH A NORTHWARD
MOVING FRONT WILL DEVELOP OVER THE SOUTHEASTERN BROOKS RANGE
TOMORROW AFTERNOON AND THEN SPREAD NORTH OVER THE NORTH SLOPE
TOMORROW NIGHT. COINCIDENT WITH THE DEVELOPING SNOW, EAST TO
NORTHEAST WINDS WILL RAMP UP ALONG THE COAST WITH BLOWING SNOW
BEING A POSSIBILITY ESPECIALLY OVER THE BEAUFORT SEA COAST AFTER
MIDNIGHT TUESDAY, BUT NOT EXPECTING ANY SIGNIFICANT REDUCTION IN
VISIBILITY. LATEST FORECAST SNOWFALL AMOUNTS OVER THE EASTERN
BROOKS RANGE WILL BE 2 TO 4 INCHES, THE HEAVIEST BEING OVER THE
SOUTH FACING SLOPES IN THE UPSLOPE FLOW. EAST OF UTQIAGVIK OVER
THE NORTH SLOPE WILL SEE UP TO 2 INCHES, POSSIBLE MORE NEAR BARTER
ISLAND. LESSER AMOUNTS AROUND AN INCH ARE EXPECTED FROM UTQIAGVIK
WEST THROUGH WEDNESDAY AFTERNOON.
COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE.
AFG WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY FOR PKZ210-PKZ220-PKZ225.
LTH OCT 18
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