343
FXAK68 PAFC 230431
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
831 PM AKDT WED OCT 22 2025
SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3)
A 959 MB STORM-FORCE LOW OVER THE CENTRAL GULF THIS MORNING HAS
BEEN DRIFTING WEST-NORTHWEST TOWARD KENNEDY ENTRANCE THROUGH THE
DAY. AS IT DOES, STRONG EASTERLY WINDS AND HEAVY RAIN SHOWERS
HAVE PERSISTED ACROSS THE NORTHERN GULF, PRINCE WILLIAM SOUND,
AND THE EASTERN KENAI PENINSULA, ALONG ITS OCCLUDED FRONT. COLDER
AIR ALOFT AND INSTABILITY ALONG THE FRONT HAS ALSO RESULTED IN A
FEW CLUSTER OF THUNDERSTORMS OVER THE COASTAL WATERS SOUTH OF
CORDOVA AND SEWARD, EMBEDDED IN THE WIDESPREAD SHOWER ACTIVITY.
FARTHER INLAND, LIGHT SNOW HAS BEEN FALLING THROUGH THOMPSON PASS
AND ALONG THE TAHNETA PASS AND EUREKA AREAS. GUSTS WINDS AREA ALSO
OCCURRING ACROSS PARTS OF THE MATANUSKA VALLEY DOWN TO KENAI, A
RESULT OF THE TIGHTENING PRESSURE GRADIENT BETWEEN THE LOW AND A
RIDGE OVER THE EASTERN INTERIOR OF ALASKA.
MODELS ARE COMING INTO BETTER AGREEMENT, CLUSTERING TOWARD THE
GFS, WITH A LOW TRACK THAT MOVES WEST THROUGH THURSDAY MORNING.
THIS LOW THEN STALLS THROUGH THURSDAY AFTERNOON AS A SECONDARY
SURFACE LOW SPINS UP WELL EAST, OVER THE NORTHEASTERN GULF. THEN,
AS THIS NEW LOW AND THE FRONT BOTH TRACK NORTHWEST AND ONSHORE
OVER THE CENTRAL CHUGACH, THE ORIGINAL LOW WEAKENS AND DRIFTS
NORTH OVER THE SOUTHERN KENAI PENINSULA.
THIS IS COMPLEX PATTERN, WITH A PLETHORA OF SUBTLE MESO-SCALE
FEATURES, INCLUDING WEAK VORTICITY LOBES EMBEDDED IN THE UPPER-
LEVEL FLOW LIFTING OVER THE COASTAL MOUNTAINS AT VARIOUS TIMES
THROUGH THE NEXT 48 HOURS. GIVEN THE INFLUX OF MOISTURE AND
EASTERLY WIND FLOW OF VARYING MAGNITUDE, THERE WILL BE TIMES OVER
THE NEXT DAY OR TWO WHEN THE SHOWER ACTIVITY SPILLS OVER THE
COASTAL MOUNTAINS INTO THE WESTERN KENAI PENINSULA, ANCHORAGE
BOWL, AND COPPER RIVER BASIN...MAINLY LATER THIS EVENING AND AGAIN
THURSDAY MORNING. THE STRONGER NORTHERLY FLOW OVER THE MAT-SU
VALLEYS, HOWEVER, WILL LIKELY KEEP NEAR SURFACE CONDITIONS DRY,
LEADING TO ONLY A FEW SPRINKLES AT BEST.
THE AIRMASS IN PLACE IS ALSO RATHER STAGNANT IN TERMS OF COLD OR
WARM AIR ADVECTION. AS SUCH, SNOW LEVELS WILL NOT CHANGE MUCH
FROM WHERE IT SITS CURRENTLY, LEADING TO MOSTLY RAIN FOR THE
SEWARD HIGHWAY CORRIDOR THROUGH FRIDAY MORNING. FOR EUREKA, 1 TO
3 INCHES OF SNOW IS POSSIBLE, WITH GREATER THAN 4 INCHES FOR
THOMPSON PASS.
BETTER CHANCES FOR PRECIPITATION ARRIVE FRIDAY MORNING AS THE
ENTIRE UPPER-LEVEL TROUGH LIFTS NORTH ACROSS SOUTHCENTRAL. COLDER
AIR WILL ARRIVE IN THE WAKE OF THE TROUGH PASSAGE LEADING TO
LOWER SNOW LEVELS. A PERSISTENT WEAK FLOW ACROSS THE COASTAL
MOUNTAINS THROUGH THE LATTER HALF OF THE WEEK WILL ALLOW FOR
PERIODS OF LIGHT PRECIPITATION AT INLAND LOCATIONS WITH CONTINUED
RAINFALL ALONG THE COAST AS LOW PRESSURE LINGERS IN THE
NORTHWESTERN GULF. EACH FEATURE EMBEDDED IN THE UPPER LEVEL
PATTERN WILL PLAY A KEY ROLE IN THE ENHANCEMENT OF THE
PRECIPITATION AND WIND OUTCOME FOR THE REST OF THE WEEK.
TM
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS
(DAYS 1 THROUGH 3: THIS AFTERNOON THROUGH SATURDAY EVENING)...
ACROSS MAINLAND SOUTHWEST ALASKA, LIGHT SNOW IN BETHEL THIS
MORNING HAS SINCE TAPERED OFF AS THIS INITIAL WAVE OF MOISTURE HAS
MOVED SOUTHWESTWARD TO THE KUSKOKWIM DELTA COAST. QUINHAGAK IS
CURRENTLY OBSERVING SNOW FROM THIS FEATURE THIS AFTERNOON. A
SECONDARY WAVE OF MOISTURE, CURRENTLY OVER ANIAK, WILL MOVE INTO
BETHEL AND AREAS SOUTHWARD STARTING LATE THIS AFTERNOON. AREAS
FROM ANIAK, BETHEL, AND SOUTHWARD TO QUINHAGAK CAN EXPECT AN
ADDITIONAL 1 TO 2 INCHES OF SNOW ACCUMULATION FROM THIS SYSTEM
THROUGH THURSDAY MORNING WITH HIGHER AMOUNTS CONFINED TO THE
MOUNTAIN RANGES. WITH REGARDS TO THE TRACK OF A LOW IN THE GULF OF
ALASKA, TRENDS TODAY HAVE BEEN FURTHER SOUTH WITH THIS FEATURE
WITH THE TRACK MORE TOWARDS THE KENNEDY ENTRANCE/BARREN ISLANDS
WITH THE STORM LINGERING THERE THROUGH FRIDAY MORNING. WITH THIS,
MORE MOISTURE CAN NOW MAKE IT INTO BRISTOL BAY. EXPECT LIGHT SNOW
AT TIMES ACROSS INTERIOR BRISTOL BAY AND THE KUSKOKWIM VALLEY
THURSDAY THROUGH FRIDAY. SNOW LINGERS ACROSS THE INTERIOR
KUSKOKWIM VALLEY ALONG THE WESTERN ALASKA RANGE THROUGH SATURDAY.
MEANWHILE, COLD NORTHERLY FLOW CONTINUES THROUGH THE EASTERN
BERING SEA SOUTHWARD TO THE PRIBILOF ISLANDS, EASTERN ALEUTIANS,
AND ALASKA PENINSULA (AKPEN). SUSTAINED NORTHERLY TO NORTHWESTERLY
GALE-FORCE WINDS ARE LIKELY THROUGH THE BAYS, GAPS, AND PASSES OF
THE AKPEN AND INTO THE NORTH PACIFIC THROUGH SATURDAY BEFORE A
WEAK RIDGE BUILDS IN BY THEN. SHOWERY RAIN/SNOW MIX IS LIKELY
ALONG THE AKPEN THROUGH SATURDAY WHILE TAPERING OFF ACROSS THE
PRIBILOF ISLANDS AND EASTERN ALEUTIANS FRIDAY MORNING.
AN UPPER-LEVEL LOW OVER KAMCHATKA WILL SEND SHORTWAVES EASTWARD
INTO THE WESTERN BERING STARTING FRIDAY. SHOWERY PRECIPITATION
ASSOCIATED WITH THESE WEAK SHORTWAVES WILL MOVE FROM THE WESTERN
ALEUTIANS TO THE CENTRAL ALEUTIANS FRIDAY MORNING THROUGH SATURDAY
MORNING. THERE CONTINUES TO BE UNCERTAINTY REGARDING A STRONGER
SHORTWAVE ROTATING AROUND THE BROAD UPPER-LEVEL KAMCHATKA LOW
FRIDAY INTO SATURDAY AND WHERE A RESULTANT SURFACE LOW WILL TRACK.
REGARDLESS OF THIS UNCERTAINTY, CONSENSUS CURRENTLY IS THAT ANY
STRONG WINDS STAY WELL OFF THE COAST OF SOUTHWEST WITH LESS THAN
SMALL-CRAFT ALONG THE COAST, SMALL-CRAFT THROUGH MUCH OF THE
CENTRAL AND WESTERN BERING, AND A CORRIDOR OF WESTERLY GALES
ACROSS THE WESTERN BERING SATURDAY EVENING. THE PARENT LOW IN THE
NORTHERN BERING, DOES LOOK TO SEND ITS FRONT EASTWARD WITH
PRECIPITATION IN THE FORM OF LIGHT SNOW TO LIGHT RAIN/SNOW MIX
REACHING THE COAST BY SATURDAY AFTERNOON AND EVENING.
LONG TERM FORECAST (DAYS 4 THROUGH 7: SUNDAY - WEDNESDAY)
THE GLOBAL MODELS ARE IN REASONABLE AGREEMENT THAT THERE WILL BE
A BROAD (OR EVEN COMPLEX) VERTICALLY STACKED LOW SOMEWHERE IN THE
CENTRAL GULF SUNDAY AFTERNOON. THE 500 MB PATTERN SHOWS A CLOSED
UPPER LOW OPENING INTO A TROUGH ACROSS SOUTHCENTRAL AND THE GULF
FOR THIS TIME, AND THE POSITIONING OF THE SURFACE LOW WILL BE
DIRECTED IN PART BY HOW MUCH AMPLIFICATION THERE WILL BE OF AN
UPPER RIDGE DOWNSTREAM OVER PARTS OF CANADA. FOR THE WESTERN
DOMAIN, THE GENERAL CONSENSUS SHOWS A DEEP, CLOSED UPPER LOW AND
POSITIVELY TILTED TROUGH ENVELOPE DRIFTING SOUTHEASTWARD OVER THE
BERING SUNDAY TO MONDAY, WHICH WILL HELP TO USHER IN AN
UNSEASONABLY COLD AIRMASS OVER THE REGION. HEADING OUT TO DAY 7 OR
SO, THERE IS A STRONG ENOUGH SIGNAL IN THE GUIDANCE THAT AN UPPER
LOW IN SOME FORM CENTERS ITSELF OVER THE SOUTHERN BERING, WHICH
INCREASES FORECASTER CONFIDENCE THAT THE ALEUTIANS AND ALASKA
PENINSULA MAY BECOME QUITE WINDY BY THE END OF THE LONG TERM
PERIOD. 850 MB TEMPERATURE ANOMALIES SHOW MARGINALLY BELOW AVERAGE
TEMPERATURES FOR SOUTHCENTRAL, WITH MORE SIGNIFICANT COLD
TEMPERATURE ANOMALIES FOR THE BERING, ALEUTIANS, ALASKA PENINSULA,
AND SOUTHWEST ALASKA THROUGH THE END OF THE LONG TERM.
-AM
AVIATION
PANC...THERE IS QUITE A BIT OF UNCERTAINTY IN THE TRACK OF A
SURFACE LOW OVER THE NORTHWESTERN GULF TONIGHT THROUGH THURSDAY.
THIS POSITION WILL BE CRITICAL TO WHETHER THE TERMINAL WILL SEE
RAIN SHOWERS OR STAY DRY. FOR NOW, THE FORECAST LEANS TOWARDS
KEEPING THE TERMINAL ON THE NORTHERN PERIPHERY OF SHOWER ACTIVITY.
THIS WILL RESULT IN LOWERING CEILINGS THIS AFTERNOON AND EVENING,
BUT STAYING SAFELY IN THE VFR CATEGORY. IF THE LOW ENDS UP TAKING
THE MORE NORTHERLY TRACK, THEN WOULD EXPECT BANDS OF LOCALLY
HEAVY SHOWERS TO TRACK UP TURNAGAIN ARM TO THE AIRPORT. WORST
CASE SCENARIO, THIS WOULD LEAD TO BRIEF PERIODS OF MVFR CEILING
AND VIS.
WITH A FAIRLY DEEP LOW PERSISTING IN THE NORTHWESTERN GULF,
NORTHERLY WINDS TO AROUND 10 KTS WILL PERSIST.
-SEB
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