476
FXAK68 PAFC 101259
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
459 AM AKDT WED SEP 10 2025
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3: TODAY
THROUGH FRIDAY)...
THE LARGE LOW THAT IS OVER KODIAK ISLAND EARLY THIS MORNING IS THE
REMNANTS OF FORMER TYPHOON PEIPAH. THIS SYSTEM REMAINS LADEN WITH
TROPICAL MOISTURE AND WILL TAKE UP RESIDENCE IN THE NORTHERN GULF
OF ALASKA FOR THE REST OF THE WEEK BEFORE FINALLY DISSIPATING
THERE THIS WEEKEND. A COLD UPPER LEVEL ARCTIC TROUGH IS IN THE
NORTHWEST PART OF THE STATE AND IS DIGGING SOUTHWARD AND WILL BE
PHASING WITH THE 500 MB LOW OF THE KODIAK LOW AS THE LOW WEAKENS.
THIS WILL CREATE COOLING AIR ALOFT AND A COLD FRONT EDGING INTO
SOUTHCENTRAL WHICH WILL COMBINE TO KEEP RAIN IN THE REGION FOR
THE NEXT FEW DAYS.
FOR TODAY, THE HEAVIEST RAINFALL SHOULD OCCUR IN THE EASTERN
KENAI PENINSULA WITH WHITTIER AND PORTAGE LIKELY SEEING THE
HEAVIEST AMOUNTS DUE TO THE EAST-SOUTHEAST FLOW. AREAS IN THE LEE
OF THE MOUNTAINS IN THIS FLOW ARE MOSTLY SEEING THE RAIN SHOWERS
DOWNSLOPING AWAY THIS MORNING AND THEREFORE THAT IS LEADING TO AN
EXPECTATION OF SCATTERED SHOWERS TODAY FOR THE WESTERN KENAI AS
WELL AS ANCHORAGE AND THE MATANUSKA VALLEY. THIS FLOW IS THEN
UPSLOPING ALONG THE WESTERN ALASKA RANGE WHICH IS NOT GOOD FOR THE
YENTNA AND SKWENTNA RIVERS AS THOSE HEADWATERS ARE GOING TO ONCE
AGAIN GET AN INCH OR TWO OF RAIN OVER THE NEXT FEW DAYS.
AS WE HEAD INTO THURSDAY AND FRIDAY, THE DIGGING ARCTIC TROUGH
WILL ENHANCE THE RAIN OVER THE COOK INLET REGION AND BRING STEADY,
AND PERHAPS HEAVY AT TIMES, RAIN FOR THE WESTERN KENAI, ANCHORAGE
AND THE MAT-SU REGIONS. THIS IS LOOKING TO BE A PROLONGED EVENT AS
THE LOW IN THE NORTHERN GULF SLOWLY DISSIPATES AND THE COLDER AIR
FILTERS INTO THE AREA CREATING GOOD LIFT OVER THE AREA. ALL THIS
COLDER AIR ALOFT WILL ALSO LEAD TO THE POTENTIAL FOR
THUNDERSTORMS ALONG THE NORTHERN GULF COAST AND INTO PRINCE
WILLIAM SOUND THURSDAY AND THURSDAY NIGHT DUE TO THE INCREASED
LAPSE RATES. AS IS TYPICAL FOR SEPTEMBER AND OCTOBER, THE BULK OF
THE COLD AIR IN THE LOWER ATMOSPHERE WILL GET BLOCKED BY THE
ALASKA RANGE AND NOT GET A GOOD PUSH INTO SOUTHCENTRAL. THIS CAN
BE SEEN IN THE FORECASTED 850 MB ISOTHERMS ON THE GFS AND NAM WITH
A 6 TO 7 DEGREE TEMPERATURE GRADIENT RIGHT ALONG THE ALASKA RANGE
ON THURSDAY AFTERNOON. HOWEVER, THERE WILL BE ENOUGH COLD AIR
FILTERING IN ALOFT THAT THERE IS A DISTINCT POSSIBILITY THAT WHEN
THE CLOUDS LIFT ENOUGH TO SEE THE TOPS OF THE MOUNTAINS ON FRIDAY
OR SATURDAY, ANCHORAGE AND THE MAT-SU COULD WITNESS THE ARRIVAL
OF THE FIRST TERMINATION DUST OF THE SEASON.
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS
(DAYS 1 THROUGH 3: TODAY THROUGH FRIDAY)...
THE CENTER OF A STACKED, WEAKENING LOW NOW RESIDES OVER THE
SOUTHERN SIDE OF KODIAK ISLAND THIS MORNING. TO THE WEST OF THE
LOW, A STILL POTENT, NORTHERLY GALE FORCE WIND FIELD CONTINUES TO
IMPACT MUCH OF THE ALASKA PENINSULA, EASTERN ALEUTIANS AND
EASTERN BERING SEA ALONG A TIGHT PRESSURE GRADIENT BETWEEN THE LOW
AND A HIGH PRESSURE RIDGE OUT OVER THE WESTERN BERING SEA. COOL
AIR IS ALSO CONTINUING TO STREAM SOUTH AND AROUND THE LOW, AND
THIS COLD AIR ADVECTION IS HELPING KEEP WINDS QUITE GUSTY ALONG
THE SOUTHWEST COAST AND AKPEN THIS MORNING. WINDS HAVE BEEN
PARTICULARLY INTENSE WHERE FAVORED CHANNELING THROUGH GAPS AND
BAYS ALONG THE SOUTHERN SIDE OF THE ALASKA PENINSULA HAS FURTHER
AMPLIFIED NORTHERLY FLOW. LOCALIZED GUSTS OVERNIGHT HAVE REACHED
60 MPH IN SPOTS SUCH AS FALSE PASS AND KING COVE, AND GUSTS UP TO
THIS THRESHOLD WILL LIKELY CONTINUE ON AND OFF THROUGH MUCH OF
TODAY INTO TONIGHT. TO THE NORTH OF THE LOW, BANDS OF LIGHT RAIN
CONTINUE TO MOVE OVER MAINLY THE MIDDLE KUSKOKWIM VALLEY AND
BRISTOL BAY. RAIN WILL END FAIRLY QUICKLY FROM WEST TO EAST TODAY
AS THE LOW CONTINUES INTO THE GULF AND AS A COOL, DRY AIR MASS
DRAWS DOWN INTO THE REGION FROM AN ARCTIC TROUGH MOVING OVER THE
WESTERN INTERIOR.
FORECAST THINKING IS STILL LITTLE CHANGED GOING THROUGH THE END OF
THE WEEK. FROM TONIGHT INTO THURSDAY MORNING, EVEN COLDER AIR
WILL DRIVE DOWN INTO SOUTHWEST AS SKIES CLEAR OUT AND AS THE
ARCTICTROUGH TO THE NORTH DIPS DOWN INTO THE LOWER KUSKOKWIM
VALLEY. MORNING LOWS ON THURSDAY WILL BE AROUND 10 DEGREES COLDER
COMPARED TO THIS MORNING, MOSTLY IN THE MID 30S TO LOW 40S.
LINGERING NORTHWESTERLY WINDS WILL LIKELY PREVENT MOST LOCATIONS
FROM SEEING A HARD FREEZE ON THURSDAY, BUT THAT MAY NOT BE THE
CASE FOR FRIDAY. NORTHWEST FLOW WILL FINALLY RELAX AND ALLOW WINDS
TO GO NEARLY CALM ON FRIDAY MORNING, AND THIS COULD YIELD THE
FIRST TRUE FROST/FREEZE FOR MANY ACROSS BRISTOL BAY AND THE LOWER
KUSKOKWIM VALLEY, ESPECIALLY IF SKIES MANAGE TO STAY MOSTLY CLEAR.
TEMPERATURES SHOULD STAY A BIT WARMER AND ABOVE FREEZING WHERE
CLOUD COVER IS MORE LIKELY TO RETURN THURSDAY NIGHT INTO FRIDAY
ALONG THE SOUTHWEST COAST AND FOR THE KUSKOKWIM DELTA.
FOR THE BERING AND ALEUTIANS, CONDITIONS WILL BE A BIT MORE
UNSETTLED FOR THE NEXT FEW DAYS, BUT STILL RATHER BENIGN. A PAIR
OF WEAK LOWS ARE EXPECTED TO SKIRT ALONG/NORTH OF THE ALEUTIAN
CHAIN FROM TODAY INTO FRIDAY, SENDING MULTIPLE ROUNDS OF RAIN
SHOWERS ACROSS THE REGION FROM WEST TO EAST. WINDS WILL PICK UP
SLIGHTLY AS THE INITIAL LOW MOVES ACROSS THE WESTERN AND CENTRAL
ALEUTIANS FROM THIS AFTERNOON THROUGH THURSDAY NIGHT. HOWEVER,
BOTH LOWS WILL STAY VERY MUCH ON THE WEAKER SIDE, AND WINDS WILL
GENERALLY STAY AT OR BELOW 25 KTS FOR MOST OF THE CENTRAL TO
WESTERN BERING/ALEUTIANS THROUGH FRIDAY AFTERNOON.
-AS
LONG TERM FORECAST (SATURDAY THROUGH TUESDAY)
LONG TERM OUTLOOK REMAINS ACTIVE IN BOTH THE SOUTHCENTRAL AND
SOUTHWEST REGIONS OF ALASKA. A TROUGH LINGERS OVER THE GULF OF
ALASKA RESULTING IN TWO AREAS OF LOW PRESSURE IMPACTING
SOUTHCENTRAL THIS WEEKEND. THE FIRST, AND STRONGEST OF THE TWO,
MOVES THROUGH THE BARREN ISLAND THEN ONSHORE BRINGING RAIN AND
WINDY CONDITIONS TO THE AREA. RAINFALL AMOUNTS CURRENTLY ARE
LIGHT. THE SECOND LOW IN THE CENTRAL GULF OF ALASKA MOVES SLOWLY
NORTHWARD TOWARD HITCHINBROOK ISLAND AND THE WESTERN PRINCE
WILLIAM SOUND BRINGING RAIN TO COASTAL AREAS.
TO BEGIN THE NEXT WEEK, A STRONG LOW SLOWLY ROTATES IN THE NORTH
PACIFIC SOUTH OF THE ALASKA PENINSULA. THE FRONT ASSOCIATED WITH
THIS LOW BRINGS ANOTHER ROUND OF WIDESPREAD RAIN SHOWERS AND
STRONG WIND FORM KODIAK ISLAND TO PRINCE WILLIAM SOUND.
-JOHNSTON
AVIATION
PANC...VFR CONDITIONS AND STEADY NORTHERLY FLOW PERSIST THROUGH
THE DAY WITH PERIODS OF LIGHT RAIN.
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