780
FXAK68 PAFC 231310
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
510 AM AKDT THU OCT 23 2025
SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3)
THE FORECAST REMAINS LARGELY ON TRACK. THE MAIN LOW IS BEGINNING
TO STALL NEAR SOUTHERN KENAI PENINSULA. MEANWHILE, A SECONDARY
SURFACE LOW IS SPINNING UP OVER THE NORTHEASTERN GULF THIS MORNING
AND IS EXPECTED TO INTERACT, NEARLY MERGING WITH THE CURRENTLY
LOW NEAR THE KENAI PENINSULA. TOGETHER, THESE LOWS TRACK
NORTHWESTWARD AND AN ADDITIONAL SURGE OF WINDS AND PRECIPITATION
WILL PUSH THROUGH PRINCE WILLIAM SOUND AND ACROSS THE CHUGACH
MOUNTAINS FOR FRIDAY MORNING.
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 FRIDAY. 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. 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. AN ADDITIONAL 2 TO 3
INCHES IS EXPECTED FOR THOMPSON PASS.
THE ENTIRE UPPER-LEVEL TROUGH LIFTS NORTH ACROSS SOUTHCENTRAL
LATER FRIDAY WITH THE POTENTIAL FOR PRECIPITATION TO SET UP AGAIN
AROUND COOK INLET. 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. OVER THE
WEEKEND, COOLER TEMPERATURES ARE EXPECTED WITH SHOWERS
DECREASING.
TM/RUX
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS
(DAYS 1 THROUGH 3: THURSDAY THROUGH THROUGH SATURDAY)...
SHIFTS IN THE TRACK OF WEATHER SYSTEMS HAVE LED TO A FEW NOTABLE
CHANGES SINCE THE PREVIOUS FORECAST PACKAGE. OTHERWISE, THE
GENERAL PICTURE REMAINS ON TRACK. SOME KEY MESSAGES:
* GUSTY WINDS CONTINUE FOR THE KUSKOKWIM DELTA COAST, WESTERN
CAPES, EASTERN BERING, AND ALASKA PENINSULA THROUGH FRIDAY
EVENING.
* WIND CHILLS REMAIN IN THE 10S AND 20S FOR MUCH OF SOUTHWEST
ALASKA AS THESE GUSTY WINDS COMBINE WITH COLD AIR TEMPERATURES.
* LIGHT PRECIPITATION WILL LEAD TO SMALL RAIN AND SNOW
ACCUMULATIONS FOR SOUTHWEST ALASKA, WITH HIGHER ACCUMULATIONS
FOR THE ALASKA PENINSULA IN PERSISTENT SHOWERS.
* FOR THE ALEUTIAN AND PRIBILOF ISLANDS, SHOWERY AND UNSETTLED AS
SMALLER-SCALE WEATHER SYSTEMS MOVE THROUGH. CONFIDENCE IS LOW
WITH THE PLACEMENT OF EACH SYSTEM.
DISCUSSION: LIGHT SNOW LINGERS IN INTERIOR KUSKOKWIM DELTA
THROUGH THE MORNING--WITH SNOW/RAIN SHOWERS ALONG THE KUSKOKWIM
DELTA COAST--AS AN UPPER LEVEL LOW DIVES SOUTH ALONG THE SOUTHWEST
ALASKA COASTLINE. BRISTOL BAY AND KUSKOKWIM VALLEY WILL ALSO PICK
UP SOME SNOW AT TIMES AS A LOW IN THE GULF MOVES INLAND, THOUGH
THE GREATEST AMOUNTS WILL REMAIN OVER HIGHER ELEVATION. FOR THE
ALASKA PENINSULA, PERSISTENT RAIN AND SNOW SHOWERS CONTINUE
THROUGH FRIDAY.
WITH MODELS TRENDING FURTHER WEST WITH THE SOUTHWEST ALASKA UPPER
LEVEL LOW, HAVE SHIFTED THE CORE OF STRONGEST WINDS FURTHER WEST.
MUCH OF SOUTHWEST ALASKA WILL STILL SEE GUSTY WINDS, BUT BRISTOL
BAY WILL BE SPARED THE SUSTAINED GALE FORCE WINDS. THERE IS STILL
SOME QUESTION OF HOW STRONG WINDS WILL BE FOR MARINE AREAS SOUTH
OF THE ALASKA PENINSULA; MODELS ARE TRENDING TOWARDS LESS ROBUST
COLD AIR ADVECTION, AND THE SHIFT TOWARDS MORE WESTERLY (RATHER
THAN NORTHWESTERLY) WINDS WILL LIKELY REDUCE ENHANCEMENT FROM
TERRAIN GAPS. STILL, THE ATMOSPHERE MAY REMAIN UNSTABLE ENOUGH FOR
STRONGER GUSTS TO MIX TOWARDS THE SURFACE FROM ALOFT.
AN UPPER-LEVEL LOW OVER KAMCHATKA WILL SEND SHORTWAVES EASTWARD
INTO THE WESTERN BERING STARTING FRIDAY. SHOWERY PRECIPITATION
ASSOCIATED WITH THESE WEAK SHORTWAVES WILL SPREAD EASTWARD ACROSS
THE BERING SEA THROUGH SATURDAY. THERE CONTINUES TO BE
UNCERTAINTY REGARDING WHERE STRONGER UPPER LEVEL SHORTWAVES MAY
HELP SPIN UP COMPACT SURFACE TROUGHS OR LOWS.
-DAN/KC
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...VFR EXPECTED WITH SURFACE WINDS PERSISTING OUT OF THE
NORTH. AS A PUSH OF WINDS INCREASE ACROSS THE CHUGACH MOUNTAINS
FRIDAY MORNING, LLWS IS POSSIBLE FRIDAY AROUND 18Z. CONFIDENCE
WITH TIMING SHOWERS REMAINS LOW TODAY, THOUGH THE MOST LIKELY
TIMEFRAME WOULD BE LATER THIS MORNING AND EARLY AFTERNOON.
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