303
FXAK68 PAFC 141357
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
557 AM AKDT MON SEP 14 2026
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3: TODAY
THROUGH WEDNESDAY)...
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 NOW IN EFFECT FOR ANCHORAGE STARTING TUESDAY
MORNING RUNNING ALL THE WAY THROUGH MIDDAY WEDNESDAY.
- A WIND ADVISORY IS ALSO NOW IN EFFECT FOR COASTAL PORTIONS OF
THE WESTERN KENAI PENINSULA FROM TUESDAY AFTERNOON THROUGH
MIDDAY WEDNESDAY.
DISCUSSION:
QUIET CONDITIONS ARE PREVAILING FOR THE TIME BEING ACROSS MOST OF
SOUTHCENTRAL AS A SHARPENING UPPER LEVEL RIDGE CONTINUES TO BUILD
ACROSS THE SOUTHERN MAINLAND. MOSTLY CLEAR SKIES HAVE AGAIN
ALLOWED TEMPERATURES TO DIP WELL INTO THE 30S AND 40S ACROSS MANY
OF THE INTERIOR VALLEYS. THE COOLING TEMPERATURES HAVE ALSO
FOSTERED RENEWED PATCHY FOG DEVELOPMENT, MOSTLY CONCENTRATED CLOSE
TO THE COOK INLET. JUST LIKE YESTERDAY, DENSE FOG IN AND AROUND
ANCHORAGE WILL BE POSSIBLE OVER THE NEXT SEVERAL HOURS, SO BE SURE
TO USE EXTRA CAUTION DURING THE MORNING COMMUTE AND BE PREPARED
FOR SUDDEN DROPS IN VISIBILITY.
ATTENTION FROM THERE TURNS TO THE FIRST IMPACTS FROM A POWERFUL
LOW PRESSURE SYSTEM EXPECTED TO RAPIDLY DEEPEN AS IT APPROACHES
THE WESTERN COAST OF ALASKA BETWEEN MONDAY AND TUESDAY. CLOUD
COVER WILL BEGIN TO INCREASE OVER THE COURSE OF THE DAY AS A WARM
FRONT 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.
ON TUESDAY MORNING, THE SURFACE LOW OUT WEST WILL REACH MAXIMUM
INTENSITY AS IT NEARS THE 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 THE
KAMISHAK GAP 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.
ITS 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.
-AS
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (DAYS
1 THROUGH 3)...
KEY MESSAGES:
- A HIGH SURF ADVISORY IS IN EFFECT FROM 1PM MONDAY TO 10PM
TUESDAY FOR THE KUSKOKWIM DELTA COAST.
- A HIGH WIND ADVISORY IS IN EFFECT FROM 10PM MONDAY TO 10PM
TUESDAY FOR NUNIVAK ISLAND AND THE KUSKOKWIM DELTA.
DISCUSSION:
THIS MORNING A NORTH PACIFIC LOW, AIDED BY A 150 KNOT JETSTREAK,
WILL LIFT ACROSS THE ALEUTIAN ISLAND CHAIN NEAR ATKA, TRACK NORTH
AND PASS WEST OF THE PRIBILOF ISLANDS THIS AFTERNOON, CONTINUE
BETWEEN ST. MATTHEW ISLAND AND NUNIVAK ISLAND, AND INTO NORTON
SOUND BY TUESDAY AFTERNOON. THIS WILL PRODUCE WIDESPREAD RAIN
SHOWERS, GUSTY WINDS, AND HIGH SURF MONDAY AND TUESDAY PRIMARILY
BETWEEN THE WESTERN CAPES AND THE KUSKOKWIM DELTA. MODELS HAVE
BEEN TRENDING TOWARDS A STRONGER SOLUTION AS MODEL CONSENSUS HAS
SLOWLY IMPROVED OVERNIGHT. WITH THAT IN MIND, THIS FORECAST HAS
BEEN CREATED WITH AN EMPHASIS TOWARD THE GFS.
CONDITIONS ALONG THE KUSKOKWIM DELTA COAST WILL BEGIN TO
DETERIORATE THIS AFTERNOON WITH HIGH SURF ALONG THE COASTLINE.
STOUT SOUTHWEST WINDS, ARE EXPECTED WITH GUSTS LIKELY TO PEAK IN
THE RANGE OF 40 TO 60 MPH BY TUESDAY AFTERNOON. COINCIDING WITH
HIGH TIDE, WATER LEVELS ARE EXPECTED TO REACH 1.0 TO 2.5 FEET
ABOVE THE NORMAL HIGH TIDE LINE. THE CORE OF STRONGEST WINDS WILL
TAKE PLACE FROM NUNIVAK ISLAND TO THE BETHEL AREA. MILDER
CONDITIONS ARE EXPECTED TO RESUME WEDNESDAY MORNING BEFORE A MUCH
WEAKER LOW ENTERS THE BERING ON THURSDAY MORNING.
LONG TERM FORECAST (THURSDAY THROUGH SUNDAY)
A MORE FALL-LIKE PATTERN IS ON THE WAY FOR THE REGION. BUT FIRST,
A SHORTWAVE RIDGE OVER EASTERN ALASKA WILL HOLD ON TO SOME OF THE
LAST FEW CRUMBS OF SUMMER FOR SOUTHCENTRAL ON THURSDAY.
MEANWHILE, TROUGHING WILL GENERATE CLOUDS WITH SHOWERS FOR THE
ALASKA PENINSULA AND SOUTHWEST. THIS TROUGH WILL MOVE EASTWARD ON
FRIDAY, PUSHING THE RIDGE AWAY, BRINGING CLOUDS AND SHOWERS TO
SOUTHCENTRAL THROUGH SATURDAY.
AN UPPER LEVEL KAMCHATKA LOW WILL ENTER THE BERING EARLY FRIDAY
AND FORM A LOW AT THE WESTERN END OF THE ALEUTIANS. THERE IS MODEL
AGREEMENT BETWEEN THE GFS AND EURO WHERE IT WILL TRACK EAST AND
CROSS INTO THE GULF BY SATURDAY. THIS LOW WOULD BRING RAIN AND
WIND FOR SOUTHCENTRAL, SOUTHWEST, AND ALASKA PENINSULA THIS
WEEKEND. THERE IS LARGE VARIANCE IN THE MODELS TRACKING THE PATH
OF THE LOW IN THE GULF, HOWEVER THERE IS AGREEMENT UPON LESS OF A
FETCH AREA FEEDING TROPICAL MOISTURE INTO THE SYSTEM. HENCE, WILL
BE MORE OF A NUISANCE WITH MINIMAL IMPACTS.
-SS
AVIATION
PANC...LIFR CONDITIONS ARE POSSIBLE AGAIN THIS MORNING AS FOG AND
LOW STRATUS ATTEMPT TO MOVE BACK INTO THE AIRPORT/WEST ANCHORAGE.
CONDITIONS SHOULD IMPROVE LATE THIS MORNING, WITH VFR CONDITIONS
EXPECTED FOR THE REMAINDER OF THE PERIOD. WINDS WILL REMAIN LIGHT
THROUGH TONIGHT, THEN BECOMING GUSTY AND SOUTHEASTERLY BY TUESDAY
MORNING. GUSTS BETWEEN 20 AND 30 KTS WILL BE POSSIBLE TOWARDS THE
END OF THE TAF PERIOD, WITH EVEN STRONGER WINDS ANTICIPATED LATER
IN THE DAY ON TUESDAY.
LM
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