059
FXAK68 PAFC 240030
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
430 PM AKDT TUE JUN 23 2026
SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3)
WIDESPREAD MODERATE TO HEAVY RAINFALL IS CURRENTLY FALLING OVER
THE SUSITNA VALLEY AS A STRONG TROUGH FROM AN UPPER LOW IN THE
GULF MOVES THROUGH SOUTHCENTRAL. LIGHTER RAINFALL IS FALLING OVER
THE MATANUSKA VALLEY WITH MORE SCATTERED RAIN OVER ANCHORAGE,
KENAI PENINSULA, AND THE COPPER RIVER BASIN DUE TO DOWNSLOPE
DRYING. RAINFALL WILL SLOWLY DIMINISH THROUGH WEDNESDAY. THE
SHORTWAVES FROM THE LOW ARE CAUSING RIDGING OVER THE CHUGACH
MOUNTAINS, WHICH IS PROMOTING GUSTY GAP WINDS IN SOUTH ANCHORAGE,
PALMER, AND THE COPPER RIVER BASIN. WINDS WILL DIMINISH BY TONIGHT
OVER THE AFOREMENTIONED AREAS AND WILL REMAIN RELATIVELY LIGHT (5
TO 10 MPH) THROUGH THE END OF THE WEEK. WINDS WILL BE LIGHT FOR
THE REST OF SOUTHCENTRAL AS WELL. TEMPERATURES TODAY WILL BE IN
THE 50S AND 60S DUE TO THE CLOUD COVER AND RAINFALL.
EASTERLY WAVES FROM THE UPPER LOW WILL CONTINUE AFTER THE MAIN
WAVE FROM TODAY DISSIPATES ON WEDNESDAY, BUT THERE WON'T BE
ENOUGH LIFT TO TRIGGER CONVECTION ON THURSDAY EXCEPT FOR MAYBE
ALONG THE WRANGELLS. TEMPERATURES WILL SLOWLY WARM THROUGH THE
WEEK AS RAIN DIMINISHES AND CLOUD COVER BREAKS. BY FRIDAY, WARMING
TEMPERATURES AND CLEARING SKIES WILL ALLOW FOR SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS ACROSS THE SUSITNA VALLEY AND THE
COPPER RIVER BASIN. THERE IS SOME UNCERTAINTY ON THE FULL
POTENTIAL OF THUNDERSTORMS FOR FRIDAY WITH THE POSSIBILITY OF MORE
OR LESS THUNDERSTORMS DEPENDING ON HOW MUCH INSTABILITY ARISES AND
THE COVERAGE OF LINGERING CLOUD COVER.
-JAR
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (DAYS
1 THROUGH 3/TONIGHT THROUGH FRIDAY)...
SOUTHWEST AK...A LARGE UPPER LEVEL LOW IS CENTERED OVER THE GULF,
WITH A SHORT-WAVE EXTENDING NORTHEASTWARD TO THE COPPER RIVER
BASIN AND INTO THE YUKON. THE SHORT-WAVE IS AMPLIFYING AS IT TRACKS
SLOWLY WESTWARD, WITH WIDESPREAD RAIN SPREADING FROM THE SUSITNA
VALLEY ACROSS THE WESTERN ALASKA RANGE TO INTERIOR SOUTHWEST AK.
OUT AHEAD OF THIS, A STOUT SHORT-WAVE RIDGE EXTENDS FROM THE AK
INTERIOR SOUTHWESTWARD TO THE KUSKOKWIM DELTA. A BAND OF SHOWERS
AND ISOLATED THUNDERSTORMS THAT MOVED OVER THE Y-K DELTA THIS
MORNING HAS LARGELY DISSIPATED. HOWEVER, BREAKS OF SUN ARE
LEADING TO SOME REDEVELOPMENT OF CONVECTION THIS AFTERNOON. WITH
FAIRLY EXTENSIVE CLOUD COVER, EXPECT SHOWER AND THUNDERSTORM
COVERAGE WILL REMAIN LESS THAN WHAT WAS OBSERVED THIS MORNING.
THE GENERAL PATTERN WILL HOLD FOR THE NEXT COUPLE DAYS
(WEDNESDAY/THURSDAY). STEADY WETTING RAINS WILL CONTINUE TO
SPREAD SOUTHWESTWARD ACROSS THE ALASKA RANGE AND INTO INTERIOR
SOUTHWEST TONIGHT, WITH THE BULK OF RAIN FALLING EAST OF A LINE
FROM SLEETMUTE TO KOLIGANEK. AREAS CLOSER TO THE ALASKA RANGE WILL
SEE UPWARD OF 1 INCH OF RAIN THROUGH TUESDAY MORNING, LEADING TO
RISING WATER LEVELS ALONG THE STONY RIVER AND OTHER TRIBUTARIES
FLOWING OUT OF THE ALASKA RANGE. THE UPPER LEVEL SHORT-WAVE WILL
STALL ALONG THE ALASKA RANGE AND SLOWLY SHEAR APART ON WEDNESDAY,
WITH RAIN OVER SOUTHWEST RAPIDLY DIMINISHING. A REMNANT AREA OF
LIGHT RAIN WILL TRACK SOUTH ACROSS BRISTOL BAY THROUGH THE DAY.
MEANWHILE, THE UPPER LEVEL RIDGE AND LOW LEVEL THERMAL TROUGH AND
AXIS OF INSTABILITY WILL BE NEARLY STATIONARY FROM THE KUSKOKWIM
MOUNTAINS NORTH AND WEST ACROSS PORTIONS OF THE Y-K DELTA. EXPECT
AN UPTICK IN SHOWERS AND THUNDERSTORMS WEDNESDAY AFTERNOON AND
EVENING FOR THESE AREAS, WITH A REPEAT EXPECTED ON THURSDAY. WHILE
THE GREATEST INSTABILITY WILL BE INLAND, STORM MOTION WILL STEER
SHOWERS AND THUNDERSTORMS SOUTHWESTWARD TOWARD THE COAST.
FOR FRIDAY, AN UPPER LEVEL SHORT-WAVE AND SURFACE FRONTAL SYSTEM
EXTENDING FROM A LOW IN THE BERING SEA WILL APPROACH SOUTHWEST AK,
THIS WILL LIKELY LEAD TO A NARROW BAND OF SHOWERS AND POSSIBLE
SOME THUNDERSTORMS OVER SOUTHWEST. THE POSITION OF THIS IS HARD TO
PINPOINT RIGHT NOW.
BERING SEA/ALEUTIANS...A SECOND UPPER LEVEL LOW IS CENTERED NEAR
THE WESTERN ALEUTIANS TODAY. A SURFACE LOW HAS FORMED OUT AHEAD OF
THIS, COINCIDENT WITH A SUBTROPICAL JET STREAK AND SHORT-WAVE
TROUGH. WHILE THE LOW WILL NOT GET MUCH STRONGER, A SERIES OF
SHORT-WAVES WITH ABUNDANT MOISTURE FROM THE PACIFIC WILL LIFT
NORTHWARD ACROSS THE ALEUTIAN CHAIN AND INTO THE SOUTHERN BERING
THROUGH WEDNESDAY. THIS WILL LEAD TO PERIODS OF RAIN, HEAVIEST
FROM AROUND NIKOLSKI TO UNALASKA/DUTCH HARBOR. ALSO EXPECT SOME
GUSTY SOUTHWEST WINDS AHEAD OF A SURFACE FRONTAL SYSTEM. THE LOW
WILL WEAKEN OVER THE CENTRAL BERING WEDNESDAY THROUGH FRIDAY. FOG
AND LOW CLOUDS WILL REMAIN A THREAT IN AREAS NOT IMPACTED BY THE
STRONGER WINDS WITH THIS SYSTEM.
-SEB
LONG TERM FORECAST (DAYS 4 THROUGH 7: SATURDAY THROUGH TUESDAY)
THE LONG-TERM PATTERN CONTINUES TO LOOK UNSETTLED ACROSS THE
BERING SEA, ALEUTIAN CHAIN, AND ACROSS THE SOUTHERN MAINLAND. A
LOW IN THE BERING SEA SPREADS SHOWERS ALONG THE ALEUTIAN CHAIN TO
THE SOUTHERN ALASKA PENINSULA SATURDAY AND SUNDAY. THIS SYSTEM
ALSO BRINGS SHOWERY CONDITIONS TO SOUTHWEST ALASKA BY SUNDAY
AFTERNOON. AT THE SAME TIME, WEAK UPPER-LEVEL SHORTWAVES LIFT
NORTHWARD FROM THE GULF OF ALASKA AND ACROSS SOUTHCENTRAL ALASKA.
THIS WILL HELP PRODUCE SHOWERS ACROSS THE SOUTHCENTRAL INTERIOR
SATURDAY AND SUNDAY; NAMELY THE COPPER RIVER BASIN AND SUSITNA
VALLEY. THERE COULD BE ENOUGH INSTABILITY IN PLACE SATURDAY AND
SUNDAY AFTERNOON ACROSS THE COPPER RIVER BASIN AND SUSITNA VALLEY
TO PRODUCE A FEW LIGHTNING STRIKES IN MORE ROBUST SHOWERY
ACTIVITY. THERE AIRMASS ACROSS SOUTHWEST ALASKA LOOKS TO BE MORE
STABLE THAN THAT ACROSS PORTIONS OF SOUTHCENTRAL, THEREFORE,
LIGHTNING STRIKES ARE LESS OF A THREAT THERE.
FOR MONDAY, THE BERING LOW THAT BROUGHT SHOWERS ACROSS THE BERING
SEA, ALEUTIANS, AND MAINLAND SOUTHWEST SATURDAY THROUGH MONDAY,
NOW SENDS IT ENERGY INTO SOUTHCENTRAL BY MONDAY EVENING.
THEREFORE, EXPECT SHOWERY CONDITIONS TO CONTINUE ACROSS MUCH OF
SOUTHCENTRAL MONDAY EVENING THROUGH MUCH OF TUESDAY.
BACK TO THE WEST, A STRONGER NORTH PACIFIC LOW AND FRONT PUSH
SUSTAINED SOUTHEASTERLY GALE-FORCE WINDS WITH STORM-FORCE GUSTS
INTO THE WESTERN ALEUTIANS AND WESTERN BERING BY MONDAY MORNING.
ALSO ACCOMPANYING THIS SYSTEM WILL BE MODERATE TO HEAVY RAIN AT
TIMES. RAIN AND GUSTY WINDS MOVE TO ADAK/ATKA BY MONDAY AFTERNOON
AND EVENING AND TO UNALASKA/NIKOLSKI BY TUESDAY MORNING.
AVIATION
PANC...VFR CONDITIONS ARE EXPECTED TO PERSIST IN SPITE OF THE
RAIN; WHICH SHOULD TAPER OFF LATE THIS EVENING. SOUTHEASTERLY
TURNAGAIN ARM WINDS WILL INCREASE AGAIN THIS AFTERNOON THROUGH
EVENING, WITH GUSTS REACHING UP TO 25 KTS.
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