319
FXAK68 PAFC 131302
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
502 AM AKDT SAT SEP 13 2025
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA
(DAYS 1 THROUGH 3: SATURDAY THROUGH MONDAY NIGHT)...
THE SURFACE LOW IN THE GULF HAS FINALLY DISSIPATED EARLY THIS
MORNING AND THE LAST OF THE UPPER LEVEL LOW IS EXITING THE
SUSITNA VALLEY TO THE NORTHWEST THIS MORNING. THIS HAS BEEN A VERY
INTERESTING SYSTEM IN THAT IT WAS A FORMER TYPHOON (PEIPAH) THAT
WENT EXTRA-TROPICAL AND THEN SLOWLY WEAKENED IN PLACE FOR DAYS IN
THE NORTHWESTERN GULF OF ALASKA. THIS REMAINED STATIONARY DUE TO
UPPER LEVEL SUPPORT DETACHING FROM THE SYSTEM DAYS AGO AND LEAVING
IT TO PUSH INTO THE FIRST STRONG COLD FRONT OF THE SEASON WHICH
MOVED THROUGH SOUTHWEST ALASKA, STALLING ALONG THE ALASKA RANGE.
THIS KEPT SOUTHCENTRAL UNDER A VERY MOIST AIRMASS IN THE AREA OF
LIFT AHEAD OF THE FRONT. IF THIS SETUP OCCURRED TWO MONTHS FROM
NOW IT MAY HAVE DROPPED ENOUGH SNOW TO STRAIN SNOW REMOVAL FOR
EVERYONE. HOWEVER, IT FELL AS RAIN EXCEPT FOR AT HIGHER ELEVATIONS
AS IT IS ONLY THE MIDDLE OF SEPTEMBER. WHILE THERE WERE
IMPRESSIVE RAINFALL VALUES IN THE EASTERN KENAI PENINSULA AND
PRINCE WILLIAM SOUND WITH LOCATIONS GENERALLY RANGING FROM 3
INCHES TO 8.5 INCHES FOR THEIR 3 DAY TOTALS AS THAT REGION IN
VULNERABLE TO THAT PERSISTENT SOUTHEASTERLY FLOW. HOWEVER, WITH
THE UPPER LEVEL SUPPORT WELL TO THE EAST, THERE WAS NO ATMOSPHERIC
RIVER TO CONTINUALLY PUMP COPIOUS AMOUNTS OF MOISTURE, LIMITING
THE RAINFALL TO MOSTLY WHAT WAS ALREADY PART OF THE ONCE- TROPICAL
AIRMASS.
EVEN WITH THE SYSTEM DEPARTING THE AREA THIS MORNING, IT DOES NOT
NECESSARILY MEAN DRY WEATHER IS HERE. THERE IS A SHORT WAVE JUST
SOUTHEAST OF PRINCE WILLIAM SOUND EMBEDDED IN THE SOUTHERLY FLOW.
THE ASSOCIATED RAIN SHOWERS CAN BE SEEN ON MIDDLETON ISLAND RADAR
AND THESE SHOWERS WILL SLOWLY MOVE NORTHWEST THROUGHOUT THE DAY
BRINGING MORE RAIN TO THE PRINCE WILLIAM SOUND REGION, THOUGH THEY
ARE NOT PART OF THE FORMER TROPICAL SYSTEM. IT LOOKS INCREASINGLY
LIKELY THAT THESE SHOWERS WILL CURVE MORE WESTERLY INTO THE
EVENING AND PERHAPS BRING A FRESH ROUND OF RAINFALL TO THE WESTERN
KENAI, ANCHORAGE, AND THE MAT-SU THIS EVENING INTO OVERNIGHT
TONIGHT, THOUGH AMOUNTS ARE NOT EXPECTED TO BE VERY MUCH.
THE NEXT BIG WEATHER-MAKER TRACKS TO THE SOUTHERN GULF SUNDAY
MORNING AS A STRONG NORTH PACIFIC LOW SENDS ITS FRONT NORTHWARD.
THIS WILL BRING IN WET AND WINDY CONDITIONS ACROSS KODIAK ISLAND
SUNDAY EVENING AND COASTAL SOUTHCENTRAL ON MONDAY. THE LOW ITSELF
MOVES INTO THE SOUTHERN GULF MONDAY MORNING AS THE FRONT MAKES IT
TO THE NORTHERN GULF COAST BY THEN. AS THE FRONT APPROACHES THE
NORTHERN GULF COAST, WINDS WILL BE ENHANCED WITH A CORRIDOR OF
STORM-FORCE WINDS SOUTH AND WEST OF KAYAK ISLAND MONDAY MORNING.
NORTHEASTERLY GALES WILL ALSO BE LIKELY THROUGH SOUTHERN COOK
INLET, SHELIKOF STRAIT, AND ALONG THE COASTAL WATERS OF THE
EASTERN KENAI PENINSULA.
EXPECT MODERATE TO HEAVY RAIN TO ACCOMPANY THE FRONT ALONG THE
COAST AS IT TRAVERSES THAT AREA SUNDAY EVENING THROUGH MONDAY.
ANCHORAGE AND MOST OF THE WESTERN KENAI PENINSULA WILL SEE LIGHT
RAIN AT TIMES MONDAY AFTERNOON AND EVENING WITH STRONG DOWNSLOPING
IN EASTERLY FLOW PRESENT AT THE 850 MB LEVEL. HOWEVER, FROM
NINILCHIK SOUTH, STEADIER LIGHT RAIN IS MORE LIKELY WITH BETTER
MOISTURE AND LIFT. MOST RAIN SUNDAY EVENING THROUGH MONDAY LOOKS
TO FALL ALONG THE NORTHERN GULF COAST, PRINCE WILLIAM SOUND, AND
KODIAK ISLAND. BETWEEN SUNDAY AFTERNOON AND MONDAY EVENING,
PORTIONS OF KODIAK ISLAND, INCLUDING KODIAK CITY, HAVE THE
POTENTIAL TO 2 TO 2.5 INCHES OF RAIN IN AROUND A 24-HOUR PERIOD.
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (DAYS
1 THROUGH 3)...
LIGHT RAIN SHOWERS ARE POSSIBLE ACROSS THE CENTRAL BERING
SEA/ALEUTIANS AS VARIOUS WEAK SURFACE LOWS EMBEDDED WITHIN A
BROAD LONGWAVE TROUGH CONTINUE SLOWLY TREKKING EASTWARD. OFFSHORE
FLOW AND MOSTLY CLEAR TO PARTLY CLOUDY SKIES CONTINUE ACROSS
SOUTHWEST ALASKA, ALLOWING FOR ANOTHER NIGHT OF TEMPERATURES IN
THE 30'S, WITH SOME AREAS DROPPING BELOW FREEZING. PRECIPITATION
IS EXPECTED TO CONTINUE TO BE NEGLIGIBLE ACROSS SOUTHWEST ALASKA
THROUGH THIS WEEKEND.
A NORTH PACIFIC LOW TRAVELS WELL SOUTH OF THE ALEUTIAN CHAIN
TOWARDS THE GULF OF ALASKA, REACHING THE SOUTHERN GULF BY SUNDAY
AFTERNOON. AN AREA OF SMALL CRAFT TO GALE FORCE WINDS IS EXPECTED
SOUTH OF THE ALASKA PENINSULA SUNDAY, AS WELL AS NORTHERLY FLOW
THROUGH GAPS AND PASSES OF THE SOUTHERN ALASKA PENINSULA AND
EASTERN ALEUTIANS.
EARLY NEXT WEEK, A STRONG FRONT LOOKS TO PUSH INTO THE WESTERN
BERING SEA AHEAD OF A LOW DROPPING SOUTH FROM KAMCHATKA. THERE
REMAINS SOME UNCERTAINTY ABOUT THE STRENGTH OF THE LOW, WITH HIGH
END GALES LIKELY AND A CHANCE FOR A CORRIDOR OF STORM FORCE
WINDS. ADDITIONALLY, A WIDESPREAD BAND OF PRECIPITATION IS
EXPECTED ALONG THE FRONTAL BOUNDARY.
LONG TERM FORECAST (TUESDAY THROUGH FRIDAY)
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 CONTINUES TO LIFT NORTH INTO THE GULF EARLY IN THE WEEK. THIS
SYSTEM LOOKS LIKELY TO PEAK IN INTENSITY TUESDAY MORNING AS IT
ENTERS THE SOUTHWESTERN GULF. HEAVY RAIN IS EXPECTED ALONG THE
EASTERN KENAI PENINSULA AND NORTHERN GULF COAST INTO TUESDAY AS
THE FRONTAL SYSTEM REACHES THE COAST. 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 THROUGH
TUESDAY AFTERNOON.
FARTHER 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 EARLY TUESDAY 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 TUESDAY 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. MVFR
CONDITIONS ARE EXPECTED TO IMPROVE TO VFR THROUGH MOST OF THE
FORECAST PERIOD. MVFR CEILINGS POSSIBLE AFTER 06Z SUNDAY.
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