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FXAK68 PAFC 031350
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
550 AM AKDT WED SEP 3 2025
SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3)
PATCHY TO AREAS OF FOG HAVE BEEN DEVELOPING THIS MORNING ACROSS
THE COPPER RIVER VALLEY, GULF COAST AND PRINCE WILLIAM SOUND, AND
UP ALONG THE COOK INLET INTO THE SUSITNA VALLEY. AREAS WITH CLEAR
SKIES SHOULD SEE FOG DISSIPATE PRETTY QUICKLY AFTER THE SUN COMES
UP AND DIURNAL MIXING BEGINS. ELSEWHERE, FOG AND LOW STRATUS MAY
LINGER UNTIL LATE MORNING OR EARLY AFTERNOON AS A FRONT LIFTS UP
ACROSS THE REGION. SHOWERS WILL ALSO ACCOMPANY THIS FRONT WITH
MOST OF THE RAIN FOCUSED OVER IN BRISTOL BAY AND THE WESTERN SIDE
OF THE ALASKA RANGE; HOWEVER, WESTERN SOUTHCENTRAL SHOULD SEE SOME
SHOWERS MOVING THROUGH. THE SUSITNA VALLEY WILL ONCE AGAIN SEE
THE MOST OUT OF THIS SYSTEM WITH RAIN MOVING UP INTO THE VALLEY
LATER THIS MORNING. SOUTHERLY 850 MB WINDS WILL AID IN FOCUSING
LIFT, AND THUS PRECIPITATION, ALONG THE HIGHER TERRAIN OF THE
ALASKA RANGE. SCATTERED SHOWERS WILL ALSO MOVE UP THE COOK INLET
TOWARDS THE ANCHORAGE BOWL AND MAT VALLEY, BUT LOOK TO FALL APART
AS THE FRONT PUSHES NORTHWARDS. THE PARENT TROUGH WILL LIKELY
LIFT INTO INTERIOR ALASKA THURSDAY WITH ANOTHER ROUND OF SCATTERED
SHOWERS DEVELOPING OVER THE SUSITNA VALLEY BEFORE PUSHING EAST
TOWARDS THE COPPER BASIN ON FRIDAY.
AHEAD OF THE AFOREMENTIONED SYSTEM, RIDGING WILL BUILD OVER THE
COPPER BASIN IN RESPONSE TO THE INCOMING TROUGH AND A LOW
RETROGRADING WESTWARDS FROM THE WEST COAST. THE THERMAL RIDGE WILL
BUILD INTO THE COPPER BASIN AND IT WOULD NOT BE SURPRISING TO SEE
TEMPERATURES FOR THE LOWER RIVER VALLEYS NUDGING BACK INTO THE
MID 70S THURSDAY AFTERNOON. THE PRESSURE GRADIENT STEEPENS OVER
THE COAST MOUNTAINS RESULTING IN GUSTY SOUTHERLY WINDS DEVELOPING
THROUGH THE SOUTHERN END OF THE BASIN THURSDAY AFTERNOON. COOLER
TEMPERATURES RETURN ON FRIDAY AND SATURDAY.
- PP
.SHORT TERM FORECAST SOUTHWEST ALASKA / BERING SEA / ALEUTIANS
(WEDNESDAY TO SATURDAY)...
THIS MORNING, A LOW PRESSURE SYSTEM IS CROSSING FROM THE NORTHERN
PACIFIC INTO THE SOUTHEASTERN BERING SEA, MOVING OVER UNIMAK
PASS. THIS LOW POSITION IS CREATING AN ARC OF MODERATE TO HEAVY
RAINFALL RATES STRETCHING FROM UNALASKA INTO THE SOUTHWEST COAST,
INCLUDING THE KUSKOKWIM DELTA AND NORTHERN BRISTOL BAY. THIS LOW
IS BRINGING GUSTY GALE FORCE WINDS TO THE EASTERN ALEUTIANS AND
SOUTHERN ALASKA PENINSULA THIS AFTERNOON AND WEDNESDAY, ALONG WITH
LIGHT TO MODERATE RAINFALL RATES. STORM-FORCE GUSTS ARE POSSIBLE
ALONG THE FAVORED SOUTHERN GAPS AND PASSES THIS MORNING, HOWEVER
THE CHANCE FOR THESE STRONG WINDS WILL DIMINISH INTO THIS
AFTERNOON AS THE LOW CENTER SHIFTS NORTHWARDS. THE LOW PUSHES
INLAND LATER THIS MORNING, INITIALLY BRINGING HEAVY RAINS TO FIRST
THE COASTAL AREAS OF SOUTHWEST, THEN INLAND AREAS BY EARLY THIS
AFTERNOON. GUSTY SOUTHERLY WINDS WILL ALSO IMPACT THE COASTAL
REGIONS, PARTICULARLY IN BRISTOL BAY BY DILLINGHAM. SOUTHERLY FLOW
IS ASSOCIATED WITH THIS LOW, SO DESPITE INCREASED CLOUD COVER AND
RAINFALL, TEMPERATURES REMAIN ON THE WARMER SIDE FOR THE
SOUTHWEST MAINLAND IN THE UPPER 50S TO LOWER 60S.
WITH A WEAK RIDGE MOVING IN ON THE BACKSIDE OF THE AFOREMENTIONED
LOW, FOG AND LOW STRATUS IS EXPECTED TO SPREAD ACROSS THE BERING
LATE TODAY AND TONIGHT. HOWEVER, ANOTHER DEEP LOW PRESSURE SYSTEM
BUILDING IN THE NORTH PACIFIC WILL PUSH A FRONT INTO THE WESTERN
ALEUTIANS LATE TONIGHT/EARLY THURSDAY MORNING. STORM-FORCE
SOUTHEASTERLY GUSTS ARE EXPECTED TO SPREAD, REACHING ADAK BY LATE
THURSDAY MORNING. THROUGH THURSDAY AND THURSDAY NIGHT, THE LOW
WILL CONTINUE TO SHIFT NORTH AND EASTWARD, BRINGING MODERATE
RAINFALL AND STRONG WINDS TO THE REMAINDER OF THE ALEUTIANS,
REACHING THE SOUTHERN ALASKA PENINSULA AND THE PRIBILOF ISLANDS BY
FRIDAY MORNING. THE WINDS WILL BE WEAKER BY THIS POINT, BUT ONCE
AGAIN, GAP WINDS COULD HAVE STRONGER GUSTS. DUE TO THE SIZE OF THE
LOW, THE BACK END OF IT WILL BRING ANOTHER ROUND OF GALE FORCE
WINDS TO THE WESTERN ALEUTIANS BY FRIDAY AFTERNOON. HEAVY RAIN
AND GUSTY WINDS WILL BEGIN PUSHING INTO THE COASTLINE IN THE
MAINLAND BY FRIDAY EVENING.
-CL
.LONG TERM FORECAST (DAYS 4 THROUGH 7 - SATURDAY THROUGH
TUESDAY)...
WINDY WITH HEAVY RAIN IN THE ALEUTIANS SATURDAY AND SUNDAY,
FOLLOWED BY MODERATE RAIN ACROSS SOUTHWEST AND WESTERN MAINLAND
MONDAY THROUGH TUESDAY.
EARLY IN THE PERIOD (SAT-SUN) THE EUROPEAN MODEL COMES INTO MORE
AGREEMENT THE GFS AND CANADIAN GUIDANCE WITH A STRONGER CYCLONE
TRACKING FROM THE EASTERN ALEUTIANS TO WESTERN ALASKA, BECOMING
SLIGHTLY WEAKER AND DISSIPATING OVER THE CENTRAL PORTION OF THE
STATE EARLY IN THE WORKWEEK. FOR THE NEXT CYCLONE, MODELS CONTINUE
TO AGREE ON ITS DEPTH AND LANDFALL ON ALASKA'S WEST COAST BY
MONDAY. THIS SYSTEM WEAKENS ON WEDNESDAY AS ANOTHER SYSTEM
APPROACHES THE WESTERN ALEUTIANS.
PERIODS OF HIGH WINDS AND FREQUENT PERIODS OF RAIN WILL SPREAD
FROM THE CENTRAL ALEUTIANS AND INTO WESTERN ALASKA AND ACROSS THE
ALASKA RANGE AS A SERIES OF LOWS PASS ACROSS THE REGION WITH
POSSIBLE GALES IN THE NORMAL GAP AREAS. SOUTHERN COASTAL AREAS
WILL SEE MODERATE TO HEAVY PERIOD OF RAINFALL MID-WEEK.
AVIATION
PANC...AREAS OF SHALLOW FOG HAVE DEVELOPED EARLY THIS MORNING IN
THE MIDST OF PARTIALLY CLEAR SKIES, HIGH AMBIENT MOISTURE, AND
CALM WINDS. WHILE INTERMITTENT LIFR VISIBILITY AND CEILINGS WILL
BE POSSIBLE WITH AREAS OF FOG MOVING NEAR THE TERMINAL OVER THE
NEXT COUPLE HOURS, IT WILL LIKELY QUICKLY BURN OFF AFTER SUNRISE
AND ALLOW A RETURN TO VFR.
ASIDE FROM THE EARLY MORNING FOG ISSUES, A BAND OF LIGHT RAIN IS
EXPECTED TO MOVE QUICKLY UP COOK INLET THIS MORNING, BUT IT WILL
WEAKEN AS IT APPROACHES THE TERMINAL LATER THIS MORNING INTO THE
EARLY AFTERNOON. CEILINGS COULD DROP BRIEFLY TO AROUND 3000 TO
5000 FT AS THIS WEAK FRONTAL WAVE PUSHES PAST TOWARDS THE LATE
MORNING HOURS, BUT ANY CHANCE TO SEE MVFR CEILINGS OR LOWER STILL
LOOKS UNLIKELY. LIGHT WINDS WILL BECOME GUSTY AND SOUTHEASTERLY
THIS EVENING AS TURNAGAIN ARM WINDS BEND NORTH INTO THE TERMINAL.
SOME UNCERTAINTY REMAINS FOR THE EXACT TIMING AND INTENSITY OF
THESE WINDS, BUT THE STRONGEST GUSTS WILL LIKELY PEAK AT AROUND 20
TO 25 KTS SOMETIME LATE THIS EVENING INTO TONIGHT.
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