806
FXAK68 PAFC 150205
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
605 PM AKDT MON SEP 14 2026
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3: THIS
AFTERNOON THROUGH THURSDAY AFTERNOON)...
KEY MESSAGES:
- A STRONG FALL STORM SYSTEM MOVING INTO WESTERN ALASKA WILL BRING
STRONG SOUTHERLY WINDS AND PERIODS OF HEAVY RAIN TO
SOUTHCENTRAL DURING THE FIRST HALF OF THE WEEK.
- A WIND ADVISORY IS IN EFFECT FOR ANCHORAGE STARTING TUESDAY
MORNING RUNNING ALL THE WAY THROUGH MIDDAY WEDNESDAY.
- A WIND ADVISORY IS ALSO IN EFFECT FOR COASTAL PORTIONS OF THE
WESTERN KENAI PENINSULA FROM TUESDAY AFTERNOON THROUGH MIDDAY
WEDNESDAY.
- A HYDROLOGIC OUTLOOK IS IN EFFECT FOR SUSITNA VALLEY, AS STEADY
RAIN COULD CAUSE LOCALIZED PONDING AND RESULT IN RIVERS REACHING
BANKFULL CONDITIONS.
DISCUSSION:
THE FORECAST REMAINS ON TRACK, WITH FEW SUBSTANTIAL CHANGES SINCE
THE MORNING PACKAGE. AS PREDICTED, CLOUD COVER IS BEGINNING TO
INCREASE ACROSS SOUTHCENTRAL AS A WARM FRONT (EXTENDING FROM THE
BERING SEA LOW) LIFTS NORTH FROM THE GULF AND UP ACROSS THE COOK
INLET AND KENAI PENINSULA. LIGHT RAIN STILL LOOKS LIKELY TO FILL
IN ALONG THE FRONT AS IT MOVES NORTH THIS EVENING INTO TONIGHT,
MAINLY FROM KENAI AND ANCHORAGE NORTH TO THE MAT-SU VALLEYS AND
TALKEETNA MOUNTAINS. EXCEPT FOR SOME GUSTY SOUTHWEST WINDS PICKING
UP BEHIND THE FRONT NEAR KODIAK, WINDS WILL STAY ON THE LIGHT
SIDE THROUGH MOST OF THE OVERNIGHT TONIGHT. EXPECT THAT TO CHANGE
QUICKLY BY THE START OF THE DAY ON TUESDAY.
BY TUESDAY MORNING, THE SURFACE LOW OUT WEST WILL REACH MAXIMUM
INTENSITY AS IT MOVES ALONG THE YUKON DELTA TOWARDS NORTON SOUND.
MEANWHILE, A STRONG SOUTHEAST TO NORTHWEST PRESSURE GRADIENT WILL
DEVELOP BETWEEN THE LOW AND HIGHER PRESSURE LINGERING OVER THE
GULF, SUPPORTING STRONG SOUTHERLY FLOW PUSHING INTO SOUTHCENTRAL.
GAP WINDS WILL QUICKLY PICK UP THROUGH THE TURNAGAIN ARM, KNIK
VALLEY AND COPPER VALLEY AS THE DAY PROGRESSES, REACHING MAXIMUM
STRENGTH DURING THE AFTERNOON HOURS ON TUESDAY. PEAK GUSTS BETWEEN
40 AND 50 MPH ARE ANTICIPATED ACROSS THE WESTERN AND SOUTHERN
PARTS OF ANCHORAGE AND NEAR GLENNALLEN, WITH SLIGHTLY WEAKER WINDS
MAKING IT INTO PALMER AND WASILLA. THERE WILL BE A BREAK IN THE
RAIN LASTING SEVERAL HOURS DURING THE MORNING HOURS FOR MOST
PLACES AWAY FROM THE MOUNTAINS, BUT THE BREAK WILL NOT LAST LONG.
BY TUESDAY AFTERNOON, THE LOW WILL BEGIN TO WEAKEN AS IT HEADS
INTO THE WESTERN INTERIOR. A TRAILING COLD FRONT WILL BEGIN TO
SWEEP ACROSS SOUTHCENTRAL FROM WEST TO EAST, SENDING ANOTHER BATCH
OF MODERATE TO HEAVY RAINFALL THROUGH THE REGION AS IT PASSES
THROUGH. GAP WINDS ACROSS THE MAT VALLEY AND TURNAGAIN ARM WILL
SHUT OFF QUICKLY BEHIND THE FRONTAL PASSAGE BY TUESDAY NIGHT.
HOWEVER, A SECOND CORRIDOR OF STRONG WINDS WILL EXTEND FROM
KAMISHAK BAY UP THE COOK INLET, SENDING ANOTHER ROUND OF STRONG
SOUTH WINDS INTO ANCHORAGE AND MUCH OF THE COASTLINE OF THE KENAI
PENINSULA, WITH GUSTS AGAIN TOPPING OUT AROUND THE 40 TO 50 MPH
RANGE OVERNIGHT ON TUESDAY NIGHT INTO EARLY WEDNESDAY MORNING. IT'S
WORTH NOTING THAT WE STILL HAVE YET TO SEE MOST OF OUR TREES
TRULY START TO TURN YELLOW, SO THEY WILL BE MORE SUSCEPTIBLE TO
DAMAGE FROM THE GUSTY WINDS THAN WHAT WE WOULD EXPECT LATER IN THE
FALL.
BY EARLY WEDNESDAY, RAIN WILL BEGIN TO TAPER OFF AS A DRIER AND
COOLER AIR MASS WORKS IN BEHIND THE FRONT AS IT EXITS TO THE EAST.
A FEW LINGERING SHOWERS COULD CONTINUE ON AND OFF THROUGHOUT THE
DAY, BUT OVERALL IT SHOULD BE MUCH DRIER COMPARED TO TUESDAY.
GUSTY SOUTH TO SOUTHWEST WINDS WILL SLOWLY RELAX THROUGH WEDNESDAY
AFTERNOON AS COLD AIR ADVECTION WANES AND AS A TRANSIENT UPPER
LEVEL RIDGE BEGINS TO BUILD BACK OVERHEAD. SHOWERS WILL LINGER
MOSTLY AT HIGHER ELEVATION, BUT AN INCOMING SHORTWAVE COULD
PRODUCE A BROADER REGION OF RAIN AROUND PRINCE WILLIAM SOUND
WEDNESDAY NIGHT INTO THURSDAY. BY THURSDAY AFTERNOON, ANOTHER LOW
MOVES FROM THE BERING SEA INTO SOUTHWEST ALASKA, BRINGING A RETURN
OF SHOWERS TO KODIAK ISLAND.
-AS/KC
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (DAYS
1 THROUGH 3)...
KEY MESSAGES:
* A COASTAL FLOOD ADVISORY IS NOW IN EFFECT UNTIL 10AM WEDNESDAY
FOR THE KUSKOKWIM DELTA COAST. WATER LEVELS ARE EXPECTED TO RISE
ANYWHERE FROM 1.5 TO 4.0 FEET ABOVE THE NORMAL HIGH TIDE LINE.
* A WIND ADVISORY IS IN EFFECT FROM 10PM THIS EVENING TO 10PM
TUESDAY FOR THE KUSKOKWIM DELTA COAST AND INTERIOR KUSKOKWIM
DELTA FOR SOUTH WINDS OF 35 TO 45 MPH WITH GUSTS TO 60 MPH
EXPECTED.
DISCUSSION:
A STEADILY DEEPENING, LARGE, ~989 MB LOW PRESSURE SYSTEM
CURRENTLY SITUATED BETWEEN SAINT PAUL AND SAINT MATTHEW ISLAND IS
DRIVING A STRONG CORRIDOR OF SOUTHERLY WINDS TOWARDS THE KUSKOKWIM
DELTA COAST THIS AFTERNOON, ACCOMPANIED WITH A ROUND OF MODERATE
RAINFALL ALONG ITS FRONT'S LEADING EDGE. WE ARE ALSO KEEPING AN
EYE ON COLD BAY THIS AFTERNOON AS THEIR WINDS BEGIN TO PEAK IN
INTENSITY. THE HIGHEST WIND GUST SO FAR TODAY AS OF 4PM HAS BEEN
54 MPH, BUT GIVEN THEIR PEAK IS NOT UNTIL THIS AFTERNOON AS THE
LOW'S FRONT CLOSES IN FROM THE WEST, AND THERE IS UPPER LEVEL
SUPPORT FROM A DIGGING, POSITIVELY TILTED LONGWAVE TROUGH WITH
WEAKER WAVES EMBEDDED, AND ANY RAINFALL COULD MIX DOWN STRONGER
WINDS TO THE SURFACE, COLD BAY COULD TICK UP TO HIGH WIND
TERRITORY BEFORE WINDS START TO DECREASE LATER THIS EVENING AND
OVERNIGHT.
OVERALL, MODELS HAVE FINALLY CONVERGED ON A MUCH STRONGER
SOLUTION FOR THIS BERING LOW, MAINLY DUE TO HIGHER CONFIDENCE IN
THE MODELS OF PHASING HAPPENING IN THE UPPER LEVELS. THIS
CONSOLIDATION OF 500 MB ENERGY IS ON TRACK TO CONTINUE
STRENGTHENING THE LOW AS IT MOVES NORTHEASTWARD THROUGH TONIGHT
TOWARDS JUST OFFSHORE OF HOOPER BAY AND EVENTUALLY TO THE NORTON
SOUND. WINDS WILL BEGIN TO INCREASE FOR THE INTERIOR KUSKOKWIM
DELTA FOR LOCATIONS LIKE BETHEL TONIGHT, AS THESE WINDS WILL NOT
BE CONFINED TO JUST COASTAL LOCATIONS. THE LOW IS PROGGED TO
BECOME A ROBUST GALE FORCE LOW WITH STORM FORCE GUSTS NEAR THE
COAST OVERNIGHT INTO TUESDAY MORNING, WITH THE CENTER OF THE LOW
LOCATED OFFSHORE OF THE YUKON-KUSKOKWIM DELTA TUESDAY MORNING.
THE PEAK IN WIND AND ONSHORE FLOW WITH SOME COASTAL FLOODING IS
MOST LIKELY TO START OCCURRING EARLY TUESDAY MORNING, WITH WIND
GUSTS UP TO 60 MPH AND WATER LEVELS UP TO 4 FEET ABOVE THE NORMAL
HIGH TIDE LINE. TO COMPOUND COASTAL IMPACTS, RAINFALL AND
INCREASED WATER LEVELS WILL BE COINCIDING WITH TWO HIGH TIDE
CYCLES, WITH THE MOST IMPACTFUL ONE LIKELY TO BE TUESDAY MORNING.
AGAIN, WINDS TO A LESSER EXTENT WILL BE MAKING IT TO THE BETHEL
AREA, WHERE WINDS ARE ON TRACK TO GUST TO 50 TO 60 MPH BY TUESDAY
AFTERNOON. AS THE SYSTEM TAKES A MORE EASTWARD BEND AND MOVES
ONSHORE SOMETIME TUESDAY AFTERNOON, WINDS WILL SHIFT FROM OUT OF
THE SOUTH AND SOUTHWEST TO OUT OF THE WEST, AND BECOME MORE
DIRECTLY IMPACTFUL TO TOKSOOK BAY AND TUNUNAK WITH WINDS BLOWING
PERPENDICULAR TO THE COASTLINE THERE. BY WEDNESDAY MORNING,
WESTERLY WINDS BEGIN TO DECREASE IN INTENSITY, BUT ELEVATED WINDS
(SUB-ADVISORY LEVEL WINDS) ARE EXPECTED TO CONTINUE THROUGH
WEDNESDAY AFTERNOON.
IN THE WAKE OF THIS SYSTEM IS ANOTHER MUCH WEAKER BERING LOW WITH
SMALL CRAFT WINDS ASSOCIATED WITH IT ON ITS SOUTHERN FLANK ON
TRACK TO SWEEP THE WESTERN AND CENTRAL ALEUTIANS LATE WEDNESDAY
MORNING, MOSTLY DUE TO THE ENHANCED PRESSURE GRADIENT BETWEEN A
STRONG HIGH LOCATED OVER THE NORTH PACIFIC AND LOWER PRESSURE
CLOSER TO THE SURFACE LOW IN THE BERING. MODELS ARE IN PRETTY
SOLID AGREEMENT THAT THE LOW TRACKS EASTWARD ACROSS THE BERING AND
JUST NORTH OF THE PRIBILOF ISLANDS THROUGH THURSDAY MORNING.
-AM
LONG TERM FORECAST (DAYS 4 TO 7)
RIDGING ACROSS THE EASTERN ALEUTIANS AND SOUTHWEST ALASKA BREAKS
DOWN LATER THIS WEEK AS A LOW AND ITS ASSOCIATED TROUGH MOVES
THROUGH THE BERING SEA. THIS BERING LOW AND ITS ASSOCIATED FRONT
BRINGS RAIN SHOWERS AND A RETURN TO CLOUDY SKIES. AS THE
FRONT MOVES TOWARD THE MAINLAND, PERSISTENT NORTHWEST FLOW WILL
OVERTAKE THE ALEUTIANS BRINGING CONTINUED RAIN SHOWERS, FOG AND
CLOUDY SKY. MODELS ARE IN BETTER AGREEMENT ON THE GENERAL TRACK
OF A SECOND LOW CROSSING THE BERING SEA AND REACHING THE CENTRAL
ALEUTIANS THIS WEEKEND. IN ITS WAKE, IT WILL BRING A CHANGE TO
NORTHERLY WINDS FOR THE AK PEN, EASTERN ALEUTIANS AND SOUTHWEST
ALASKA EARLY NEXT WEEK.
A RECEDING RIDGE OF HIGH PRESSURE IN THE SOUTHERN GULF OF ALASKA
BRINGS THE RETURN OF SOUTHWEST TO NORTHEAST FLOW INTO SOUTHCENTRAL
FOR THE WEEK'S END. THIS FLOW RESULTS IN RAINY AND CLOUDY
CONDITIONS FOR THE PRINCE WILLIAM SOUND AND EASTERN KENAI
PENINSULA FORM LATE THIS WEEK INTO THE END OF NEXT WEEKEND. TIMING
AND EXACT LOCATION DIFFERENCES ARE PRESENT THOUGH A WEAK LOW MOVES
THROUGH THE NORTHERN GULF OF ALASKA IN THE LATTER PART OF THIS
WEEKEND BRINGING RAIN TO ALREADY SATURATED PRINCE WILLIAM SOUND
COASTLINE.
AVIATION
PANC...VFR CONDITIONS EXPECTED THIS AFTERNOON AND EVENING. WINDS
WILL REMAIN LIGHT THROUGH THE AFTERNOON, SHIFTING TO SOUTHEASTERLY
AND INCREASING TUESDAY MORNING. BY MIDNIGHT TONIGHT, MVFR CEILINGS
MAY MOVE OVER THE TERMINAL ALONG WITH LIGHT RAIN SHOWERS. THROUGH
TUESDAY MORNING, EXPECT WINDS TO INCREASE QUICKLY OUT OF THE
SOUTHEAST, WITH GUSTS TO 40 KNOTS EXPECTED BY 18Z.
CL
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page