004
FXAK68 PAFC 120026
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
426 PM AKDT THU SEP 11 2025
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA
(DAYS 1 THROUGH 3: THIS AFTERNOON THROUGH SUNDAY EVENING)...
RAIN...IT CONTINUES TO RULE THE ROOST ACROSS SOUTHCENTRAL THE
NEXT FEW DAYS AS THE FORECAST REMAINS MOSTLY ON TRACK THROUGH THE
SHORT-TERM.
DIVING INTO THE DETAILS: THE LOW, WHICH IS THE REMNANTS OF FORMER
TYPHOON PEIPAH, IS NOW JUST SOUTH OF THE KENAI PENINSULA WHERE IT
WILL GENERALLY SIT AND WEAKEN UNTIL FINALLY DISSIPATING ON
SATURDAY. THE FEATURE THAT HAS A LITTLE MORE UNCERTAINTY IS THE
UPPER LEVEL ARCTIC TROUGH THAT IS DIGGING INTO SOUTHWEST ALASKA
AND EDGING SLOWLY EASTWARD. THIS FEATURE CAN BE SEEN QUITE WELL ON
GOES-18 SATELLITE IMAGERY AS THE NEARLY STRAIGHT NORTH-TO-SOUTH
EDGE TO THE CLOUDS THAT STRETCHES FROM THE ARCTIC COAST TO NEAR
WESTERN ALASKA RANGE. WITH COLD AIR FILTERING INTO SOUTHCENTRAL
AND BEING ENTRAINED INTO THE LOW, WINDS ARE INCREASING THROUGH THE
KAMISHAK GAP AND BRINGING GALE FORCE WINDS INTO THE BARREN ISLANDS
AREA. GALES WILL DIMINISH BACK TO SMALL CRAFT FRIDAY MORNING.
AS THE COLD AIR ALOFT MOVES IN, IT IS DESTABILIZING THE
ATMOSPHERE WHICH IS BRINGING A CHANCE FOR THUNDERSTORMS ALONG THE
NORTH GULF COAST AND INTO THE NORTHERN GULF FOR THIS AFTERNOON
THROUGH EARLY FRIDAY AFTERNOON. THE OTHER AREAS WITH A CHANCE FOR
THUNDERSTORMS WILL BE IN THE NORTHEASTERN COPPER BASIN THE NEXT
FEW DAYS AS THERE WILL BE COLD AIR ALOFT AND WITH A FEW BREAKS IN
THE CLOUDS THERE, IT COULD KICK OFF AN ISOLATED THUNDERSTORM OR
TWO.
ONE OTHER QUESTION WITH THIS SYSTEM IS EXACTLY HOW LOW FREEZING
LEVELS WILL BE AS THEY LOWER OVER THE NEXT FEW DAYS. THERE IS A
SIGNIFICANT AMOUNT OF RANGE (DISAGREEMENT) IN MODEL SOLUTIONS. THE
GFS CONTINUES TO BE THE WARMEST SOLUTION WITH NAM AND CANADIAN
COLDER WITH RESPECT TO FREEZING LEVELS. THERE CONTINUES TO BE A
CHANCE FOR SNOW TO REACH THE MOUNTAINS DOWN TO ABOUT 4000 FT IN
ANCHORAGE AND THE MATANUSKA VALLEY REGIONS FRIDAY OR SATURDAY. AS
ONE GOES NORTH IN THE SUSITNA VALLEY, THERE IS A CHANCE OF SNOW
MAKING IT DOWN TO CLOSER TO ROAD LEVEL WITH BROAD PASS HAVING THE
POTENTIAL FOR SNOWFALL LATE TONIGHT AND FRIDAY NIGHT. HOWEVER,
SNOW IS NOT EXPECTED TO ACCUMULATE, BUT MORE OF A "WHITE RAIN"
NATURE.
THE FORECAST BECOMES MORE UNCLEAR FOR SUNDAY AND THE BEGINNING OF
THE NEXT WORK WEEK. ANOTHER NORTH PACIFIC LOW IS POISED TO LIFT
TO NEAR THE SOUTHERN GULF BY SUNDAY. THE JURY REMAINS OUT ON HOW
FAR EAST OR WEST THE STORM WILL BE. THE GFS/NAM/GFS ENSEMBLES ARE
THE STRONGEST SOLUTIONS AND MOST WEST SOLUTIONS. THIS MEANS MORE
RAIN AND WIND FOR KODIAK ISLAND SUNDAY AFTERNOON INTO MONDAY. IN
CONTRAST, THE CANADIAN/ECMWF AND THEIR RESPECTIVE ENSEMBLE
PACKAGES HAVE A WEAKER STORM THAT MORE EAST AND ALIGNED TOWARD THE
CENTRAL GULF. THIS WOULD BE A SOMEWHAT DRIER AND LESS WINDY
SOLUTION FOR KODIAK ISLAND SUNDAY INTO MONDAY. STAY TUNED AS
DETAILS BECOME CLEARER WITH TIME ON THIS NEXT STORM SYSTEM.
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS
(DAYS 1 THROUGH 3: TONIGHT THROUGH SUNDAY)...
RELATIVELY CALM CONDITIONS HAVE OVERSPREAD MUCH OF THE BERING SEA,
ALEUTIAN ISLANDS, AND SOUTHWEST ALASKA THIS AFTERNOON. SEVERAL
WEAK FEATURES ARE PRODUCING AREAS OF LIGHT RAIN SHOWERS ACROSS THE
BERING SEA, WHILE COLD, DRY AIR CONTINUES TO STREAM SOUTH ACROSS
SOUTHWEST ALASKA, BRISTOL BAY, AND THE ALASKA PENINSULA, WITH A
SMALL CORRIDOR OF GALE FORCE WINDS SOUTH OF THE ALASKA PENINSULA
OUT OF WIDE BAY. GUSTY WINDS HAVE ALREADY BEGUN TO RELAX FOR MANY
LOCATIONS FURTHER SOUTH ALONG THE ALASKA PENINSULA AND WILL
CONTINUE TO DIMINISH TONIGHT ACROSS THE REGION AS A WEAKENING LOW
IN THE GULF OF ALASKA CONTINUES TO DRIFT EAST AND EXERT LESS AND
LESS INFLUENCE IN THE AREA. CALMING WINDS WILL ALLOW A LAYER OF
COLD AIR TO DEVELOP NEAR THE SURFACE TONIGHT FOR MANY LOCATIONS IN
SOUTHWEST ALASKA, ESPECIALLY WHERE SKIES ARE CLEAR NOW OR CLEAR
OUT TONIGHT. THIS WILL ALLOW TEMPERATURES TO DROP TO NEAR
FREEZING, BRINGING THE FIRST FROST/FREEZE OF THE SEASON. THE
CURRENT CLOUD COVER OVER SOUTHWEST ALASKA LOOKS TO DIMINISH
TONIGHT, WHICH SHOULD ALLOW FOR COLDER LOW TEMPERATURES THAN LAST
NIGHT FOR MUCH OF BRISTOL BAY, INTERIOR PORTIONS OF THE KUSKOKWIM
DELTA, AND PORTIONS OF THE KUSKOKWIM VALLEY AWAY FROM THE WESTERN
ALASKA RANGE.
THROUGH THE END OF THE WEEK, SIMILAR MILDLY UNSETTLED CONDITIONS
PREVAIL AS THE WEAK FEATURES CONTINUE TO DRIFT WITHIN A BROAD
UPPER LEVEL TROUGH. TEMPERATURES MAY DROP TO FREEZING AGAIN FRIDAY
NIGHT/SATURDAY MORNING AS COLD AIR REMAINS IN PLACE. THE ONE
FORECAST UNCERTAINTY IS WHETHER SKIES REMAIN CLEAR, AND IF THEY DO
NOT, TEMPERATURES MAY REBOUND A FEW DEGREES. LIGHT, REMNANT GAP
WINDS HOLD ON ACROSS THE ALASKA PENINSULA FROM ABOUT CHIGNIK NORTH
THROUGH SATURDAY, BUT REMAIN AT OR BELOW 20 KNOTS (~25 MPH).
HEADING INTO THE WEEKEND, THE BROAD UPPER-LEVEL TROUGH AMPLIFIES,
WHICH INDUCES THE DEVELOPMENT OF A LOW SOUTH OF KODIAK THAT TRACKS
INTO THE GULF OF ALASKA. THERE IS SIGNIFICANT UNCERTAINTY IN THE
TRACK OF THIS LOW, AND IT HAS POTENTIAL TO BRING NORTH TO
NORTHEASTERLY WINDS SOUTH OF THE ALASKA PENINSULA AND
PRECIPITATION ALONG THE COAST WITH A MORE WESTERN TRACK, BUT A
FURTHER EAST TRACK WOULD PRODUCE LIMITED IMPACTS. MEANWHILE, COOL
AIR REMAINS IN PLACE OVER SOUTHWEST ALASKA AND AREAS OF LIGHT RAIN
SHOWERS TRAVERSE THE BERING SEA/ALEUTIANS. STAY TUNED TO THE
FORECAST FOR FURTHER REFINEMENTS.
QUESADA
LONG TERM FORECAST (MONDAY THROUGH THURSDAY)
THE ACTIVE PATTERN CONTINUES IN THE LONG TERM WITH THE MAIN STORY
BEING A PAIR OF LOWS BRINGING WIND AND RAIN FROM THE ALEUTIANS TO
MUCH OF THE MAINLAND. MODELS ARE IN FAIRLY GOOD AGREEMENT WITH
THE MAIN FEATURE TO BEGIN THE PERIOD AS A LARGE 980-990 MB SURFACE
LOW LIFTS NORTH INTO THE GULF FOR MONDAY. THIS SYSTEM LOOKS
LIKELY TO PEAK IN INTENSITY MONDAY MORNING AS IT ENTERS THE
SOUTHWESTERN GULF. HEAVY RAIN IS EXPECTED ALONG THE EASTERN KENAI
PENINSULA AND NORTHERN GULF COAST MONDAY INTO TUESDAY AS THE
FRONTAL SYSTEM REACHES THE COAST MONDAY MORNING. GUSTY NORTHERLY
WINDS ACROSS THE ALASKA PENINSULA ENHANCED BY COLD AIR ADVECTION
ON THE BACKSIDE OF THE LOW AS WELL AS THE POTENTIAL DEVELOPMENT OF
A GALE-FORCE BARRIER JET OUTSIDE OF PRINCE WILLIAM SOUND AHEAD OF
THE FRONT REMAIN POSSIBLE FROM THE BEGINNING OF THE PERIOD MONDAY
MORNING INTO TUESDAY MORNING.
FURTHER WEST, A SERIES OF SHORTWAVES EMERGING FROM THE KAMCHATKA
REGION AND NORTH PACIFIC LOOK TO MERGE AS THEY ENTER THE WESTERN
BERING, SHIFTING THE AXIS OF THE LONGWAVE TROUGH TO A MORE
POSITIVE TILT OVER THE BERING. THIS BECOMES THE DOMINANT FEATURE
IN THE LATTER HALF OF THE LONG TERM AS THE DECAYING SYSTEM IN THE
GULF GETS ABSORBED, FORMING A LARGE UPPER LEVEL LOW LIFTING FROM
THE NORTH PACIFIC TOWARDS BRISTOL BAY. THIS SYSTEM REACHES THE
WESTERN ALEUTIANS BY MONDAY AND TRACKS ALONG AND JUST TO THE SOUTH
OF THE ALEUTIAN CHAIN AND ALASKA PENINSULA, SPREADING RAINFALL
AND ELEVATED WINDS WEST TO EAST ACROSS THE ALEUTIANS AND AKPEN
FROM MONDAY THROUGH WEDNESDAY. MODEL SPREAD AND UNCERTAINTY IN THE
EASTWARD EXTENT OF THE TRACK REMAINS HIGH AT THIS TIME, BUT
EXPECT RAIN TO SPREAD INTO SOUTHWEST ALASKA AS THE LOW LIFTS
TOWARDS BRISTOL BAY AS THE FRONT SHIFTS EAST AND BRINGS ANOTHER
ROUND OF RAIN TO THE GULF LATE NEXT WEEK.
AVIATION
PANC...LIGHT NORTHERLY WINDS ARE EXPECTED TO PERSIST ALONG WITH
NEARLY CONTINUOUS RAIN AS A SURFACE LOW SOUTH OF THE KENAI
PENINSULA BRINGS SHOWERS OVER THE MOUNTAINS AND INTO THE TERMINAL.
GIVEN THE SATURATED ENVIRONMENT AND NEARLY CONTINUOUS RAIN, CIGS
AND VIS WILL LIKELY REMAIN BETWEEN IFR AND MVFR THROUGH THIS
EVENING, WITH LIFR DEVELOPING AFTER MIDNIGHT.
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