798
FXAK68 PAFC 220108
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
508 PM AKDT MON SEP 21 2026
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3:
TODAY THROUGH THURSDAY)...
UPPER LEVEL TROUGHING CONTINUES OVER MAINLAND ALASKA THIS
AFTERNOON. AN OCCLUDED LOW MOVED ONSHORE IN PRINCE WILLIAM SOUND
THIS MORNING AND CONTINUES TO WEAKEN OVER THE KENAI PENINSULA.
WITH A NEGATIVE TROUGH AXIS PROVIDING UPPER LEVEL SUPPORT, THIS
HAS BROUGHT WIDESPREAD SHOWERS ACROSS SOUTHCENTRAL, WITH MOST
PERSISTENT RAIN OCCURRING ALONG THE NORTHERN GULF COAST AND THE
MAT-SU VALLEYS. SOME GUSTY SOUTHERLY WINDS ARE ALSO PRESENT IN THE
COPPER RIVER BASIN. SHOWERS WILL CONTINUE ACROSS MUCH OF
SOUTHCENTRAL INTO THE OVERNIGHT AS THE LOW SLOWLY DISSIPATES, WITH
HEAVIEST AND MOST PERSISTENT RAIN ALONG THE NORTHERN GULF COAST
AND THE WESTERN ALASKA RANGE. MOST AREAS WILL DRY OUT BY TOMORROW
(TUESDAY) MORNING. GUSTY WINDS IN THE COPPER RIVER BASIN ALSO CALM
DOWN OVERNIGHT TONIGHT.
AT THE BASE OF THE TROUGH, AN UPPER LEVEL LOW SITS OVER THE GULF
SOUTHEAST OF KODIAK ISLAND. THIS PULLS IN A SURFACE LOW FROM THE
NORTH PACIFIC INTO THE GULF ON TUESDAY. DUE TO ADVECTION OF COLD
AND DRY AIR FROM THE PREVIOUS LOW, THIS NEXT LOW LOSES ACCESS TO
WARM AIR FASTER AND OCCLUDES MUCH FURTHER SOUTH. SOME SHOWERS AND
SMALL- CRAFT FORCE WINDS ARE LIKELY ACROSS THE GULF TUESDAY INTO
WEDNESDAY AS THE LOW OCCLUDES AND SLOWLY WEAKENS.
WITH THIS LOW STALLING IN THE GULF, WEATHER ACROSS SOUTHCENTRAL
WILL BE RELATIVELY QUIET TUESDAY THROUGH THURSDAY AFTERNOON. SOME
SHOWERS LIKELY LINGER ALONG THE ALASKA RANGE AND THE NORTHERN GULF
COAST THROUGH TUESDAY AFTERNOON, OTHERWISE TUESDAY LOOKS DRY. WITH
THE ADVECTION OF DRIER AIR, CLOUDS LIKELY CLEAR OUT ACROSS MUCH
OF SOUTHCENTRAL LATE ON TUESDAY. THIS WILL RESULT IN COLDER
OVERNIGHT TEMPERATURES, WITH WIDESPREAD 20S POSSIBLE FOR THE
COPPER RIVER BASIN AND LOW TO MID 30S ELSEWHERE. SOME TYPICALLY
COLDER LOCATIONS MAY SEE COLDER TEMPERATURES WEDNESDAY MORNING AS
EAST ANCHORAGE, SOLDOTNA, BUTTE, AND WILLOW MAY DROP INTO THE
UPPER 20S AND SOME LOWS IN THE TEENS ARE POSSIBLE IN THE COPPER
RIVER BASIN. WEDNESDAY AND MOST OF THURSDAY WILL SEE DRY
CONDITIONS ACROSS SOUTHCENTRAL WITH HIGH TEMPERATURES IN THE LOW
TO MID 50S. CLOUD COVER INCREASES ACROSS SOUTHCENTRAL THURSDAY
AFTERNOON.
A MUCH MORE POTENT SYSTEM IN THE BERING SENDS A STRONG FRONT INTO
THE SOUTHWESTERN GULF AND KODIAK ISLAND THURSDAY AFTERNOON/EVENING.
CONFIDENCE IS STILL MEDIUM WITH THE TIMING OF THE FRONT AS MODELS
SLIGHTLY DIFFER ON PROGRESSION, BUT THE FRONT WILL BRING HEAVY
RAIN AND SOUTHEASTERLY, LIKELY GALE-FORCE WINDS AS IT MOVES
THROUGH. THIS FRONT CONTINUES NORTHWARD TO THE NORTHERN GULF COAST
ON FRIDAY.
- PA
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (DAYS
1 THROUGH 3: THIS AFTERNOON THROUGH THURSDAY AFTERNOON)...
KEY MESSAGES:
* A STRONG BERING SEA LOW IS FORECAST TO IMPACT THE BERING SEA,
ALEUTIAN AND PRIBILOF ISLANDS, AND SOUTHWEST ALASKA FROM ABOUT
WEDNESDAY AFTERNOON THROUGH AT LEAST THURSDAY AFTERNOON.
HOWEVER, FORECAST CONFIDENCE REMAINS FAIRLY LOW AT THIS TIME.
* FOR THE BERING SEA: AREAS OF GALE FORCE WINDS WITH STORM FORCE
GUSTS LIKELY. GUSTS TO HURRICANE FORCE POSSIBLE. EXPECT ELEVATED
WAVE HEIGHTS, WITH SEAS UP TO 25 TO 35 FT POSSIBLE. HIGH SURF
POSSIBLE FOR PRIBILOF ISLANDS.
* FOR SOUTHWEST ALASKA: SOUTHEASTERLY GALE FORCE WINDS
INCREASINGLY LIKELY (50-60% CHANCE). LOCALIZED HIGH SURF AND
COASTAL FLOODING POSSIBLE, WITH PRIMARY COMMUNITIES OF CONCERN
BEING KWIGILLINGOK AND KONGIGANAK.
DISCUSSION:
WEAK LOW PRESSURE LINGERING OVER THE EASTERN BERING SEA AND HIGH
PRESSURE RIDGING OVER THE CENTRAL BERING SEA IS PROMOTING GUSTY
NORTHERLY GAP WINDS ALONG THE SOUTHERN ALASKA PENINSULA, AS WELL
AS PERSISTENT LIGHT RAIN SHOWERS THROUGH TONIGHT. RIDGING IN THE
BERING WILL SHIFT EASTWARD OVER THE NEXT COUPLE OF DAYS, MOVING
ONSHORE OVER SOUTHWEST ALASKA, ALLOWING FOR DRIER CONDITIONS AND
CLEARER SKIES. ADDITIONALLY, COOLER AIR IS FILTERING SOUTH ACROSS
SOUTHWEST ALASKA, BRINGING COLDER OVERNIGHT TEMPERATURES INTO THE
THE LOW 30'S AND UPPER 20'S. OUT WEST, A FRONT MOVES INTO THE
WESTERN ALEUTIANS AND BERING SEA, BRINGING A ROUND OF WIDESPREAD
PRECIPITATION AND SMALL CRAFT WINDS.
THIS FRONT (AND ITS PARENT LOW) WILL BE A MAJOR AREA OF FOCUS AS
IT INTERACTS WITH THE REMNANTS OF TYPHOON DUJUAN FROM WEDNESDAY
THROUGH THURSDAY. NOT MUCH HAS CHANGED SINCE YESTERDAY, THOUGH
THE LATEST MODEL SOLUTIONS SEEM TO BE CONVERGING ON A STRONGER
LOW (CENTRAL PRESSURE AS LOW AS 950 TO 960 MB) AND WITH THE LOW
REACHING PEAK STRENGTH IN THE MIDDLE OF THE BERING SEA. IN
ADDITION, THOUGH THERE IS STILL QUITE A BIT OF UNCERTAINTY WITH
THE LOCATION OF THE LOW CENTER, THERE SEEMS TO BE DECENT AGREEMENT
THAT A GALE FORCE FRONT WILL SWEEP ACROSS THE SOUTHWEST ALASKA
COAST.
SO WHAT DOES THIS ALL MEAN? WITH THE LOW LOOKING MORE
LIKELY TO REACH PEAK STRENGTH IN THE BERING SEA, THIS MEANS THAT
HURRICANE FORCE GUSTS (>= 75 MPH) WILL BE MORE LIKELY ACROSS THE
BERING SEA, ALEUTIANS, AND PRIBILOFS THAN IN SOUTHWEST ALASKA.
ADDITIONALLY, WITH THE LOW'S CENTRAL PRESSURE REMAINING MUCH
HIGHER (AND THEREFORE, WEAKER) THAN THE 930 TO 940 MB THAT MODELS
WERE SUGGESTING A FEW DAYS AGO, WINDS LIKELY WON'T REACH AS HIGH
AS 90 MPH. STILL, THE COMBINATION OF STRONG WINDS AND THE
POTENTIAL FOR LONG FETCH COULD LEAD TO HIGH SEAS, PERHAPS ON THE
ORDER OF 25 TO 35 FT, AND THE POTENTIAL FOR HIGH SURF. FOR
SOUTHWEST ALASKA, SOLUTIONS SHOWING A GALE FORCE FRONT MOVING
THROUGH ARE INDICATIVE OF THE POTENTIAL FOR HIGH SURF AND COASTAL
FLOODING, ESPECIALLY FOR COMMUNITIES THAT ARE TYPICALLY HIT HARDER
BY STRONG SOUTHEAST WINDS (LIKE KONGIGANAK AND KWIGILLINGOK). HOW
LONG THESE WINDS WILL PERSIST, AS WELL AS WHETHER THESE AREAS
COULD SEE A SUBSEQUENT ROUND OF SOUTHWESTERLY WINDS BEHIND THE
LOW, WILL ULTIMATELY DEPEND ON THE LOW TRACK. WITH WINDS BEGINNING
TO PICK UP AS EARLY AS WEDNESDAY AFTERNOON ACROSS THE BERING, AND
THURSDAY MORNING FOR SOUTHWEST ALASKA, NOW IS A GOOD TIME TO MAKE
PLANS FOR HOW YOU'LL RESPOND IF THE FORECAST LOOKS INCREASINGLY
HAZARDOUS. STAY TUNED.
KM/KC
LONG TERM FORECAST (DAYS 4 THROUGH 7)
KEY MESSAGES:
- A VERY STRONG LOW PRESSURE SYSTEM WILL DEVELOP OVER THE BERING
SEA BETWEEN LATER THIS WEEK.
- A SEPARATE LOW PRESSURE DEVELOPS IN THE GULF OF ALASKA LATER
THIS WEEK.
A LOW FORMING IN THE BERING SEA LATER THIS WEEK COULD INCLUDE
MOISTURE FROM THE REMNANTS OF EX-TYPHOON DUJUAN. DESPITE VARYING
DIFFERENCES IN THE LOW'S FORMATION AND ITS TRACK EASTWARD THE PAST
72 HOURS, A CONSISTENT THEME HAS BEEN THAT MOST OF THE MOISTURE
FROM THE EX- TYPHOON WILL REMAIN SOUTH OF THE ALEUTIAN CHAIN. THE
MOISTURE AND HEAT BEING ENTRAINED INTO THIS BERING SEA LOW WILL
BRING WIDESPREAD RAIN AND WIND GUSTS TO THE BERING SEA. MODELS
CONTINUE TO SHOW THIS BERING LOW STRENGTH RANGING FROM 960 TO 970
MB TODAY; DESPITE ITS MORE NORTHERLY TRACK AND MOST ENSEMBLE MODEL
GUIDANCE PLACING ITS FORMATION LOCATION FROM THE PRIBILOF ISLANDS
TO THE CENTRAL ALEUTIANS. ANOTHER COMMON THEME HAS BEEN THE
ALEUTIAN ISLANDS, FROM ATTU THROUGH DUTCH HARBOR, WILL LIKELY SEE
THE STRONGEST WINDS IN THIS STORM WITH GUSTS EXCEEDING 70 MPH AT A
40% TO 60% CHANCE THURSDAY TO SATURDAY.
AS FOR SOUTHCENTRAL AND THE GULF OF ALASKA REGION: A LOW THAT
TRACKS SOUTH OF THE ALEUTIANS WILL MAKE ITS WAY TO THE GULF OF
ALASKA REGION BY FRIDAY. AT THIS TIME, IT DOES APPEAR LIKELY THAT
A FAIRLY STRONG FRONT WILL MOVE INTO THE GULF OF ALASKA BY
DURING THE DAY THURSDAY BRINGING RAIN AND WIND TO THE GULF
REGION. WIND SPEEDS EXCEEDING 60 MPH ALONG THE EASTERN KENAI
PENINSULA AND THE GULF OF ALASKA RANGE FROM A 40% TO 60% CHANCE
LATE THIS WEEK AND INTO THE WEEKEND. THE GREATEST RAINFALL AMOUNTS
FROM THIS STORM CURRENTLY ARE ALONG THE COAST FROM THE EASTERN
KENAI PENINSULA TO CORDOVA FRIDAY AFTERNOON THROUGH SUNDAY
EVENING.
AVIATION
PANC... PERIODS OF RAIN CONTINUE THROUGH THE OVERNIGHT HOURS WITH
LIGHT AND VARIABLE WINDS CONTINUING. CLOUD HEIGHTS AND CEILINGS
RISE OVERNIGHT THOUGH PERIODS OF MVFR TO VFR CONDITIONS WILL
PERSIST THROUGH TOMORROW MORNING. LIGHT AND VARIABLE WINDS TURN
MORE NORTHERLY TOMORROW MORNING WITH THE PASSING OF A WEAK
SHORTWAVE OVERNIGHT. WIND SPEEDS REMAIN LIGHT, THOUGH.
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