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FXAK68 PAFC 301303
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
503 AM AKDT MON JUN 30 2025
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3: TODAY
THROUGH WEDNESDAY)...
A SHORTWAVE IS ROTATING SOUTHWESTWARD THROUGH THE COPPER RIVER
BASIN AND AS FAR WEST AS THE MATANUSKA VALLEY EARLY THIS MORNING,
BRINGING SHOWERS TO GLENNALLEN AND PALMER, AS WELL AS TO AREAS
AROUND PRINCE WILLIAM SOUND. THIS SHORTWAVE WILL BEGIN TO TRACK
MORE NORTH-TO-SOUTH AS THE DAY GOES ON IN RESPONSE TO WEAK
RIDGING OVER THE WESTERN ALASKA RANGE SOUTHWARD TO KODIAK. THE
PRESSURE RISES ASSOCIATED WITH THE RIDGING WILL ALSO KEEP
SOUTHWESTERLY FLOW THROUGH COOK INLET TODAY WHICH WILL KEEP CLOUDS
PACKED UP ALONG THE WESTERN SLOPES OF THE CHUGACH, KENAI, AND
TALKEETNA MOUNTAINS THROUGH TONIGHT. BY TUESDAY, THE SHORTWAVE
SHOULD BE WELL OUT OF THE AREA AND THE WEAK RIDGING OVER
SOUTHCENTRAL WHICH SHOULD ALLOW SOME SEMBLANCE OF CLEARING, THOUGH
WEDNESDAY ACTUALLY LOOKS LIKE A MORE LIKELY DAY FOR THE NICE
WEATHER DAY OF THE WEEK AS THE SURFACE AND UPPER LEVEL RIDGE WILL
BE BETTER ALIGNED RESULTING IN BETTER SUBSIDENCE AS WELL AS THE
SYNOPTIC FLOW NO LONGER DRIVING THE MOISTURE UP COOK INLET WHICH
SHOULD RESULT IN LESS CLOUD COVER. BY EARLY TUESDAY, A FRONT
ASSOCIATED WITH A LOW IN THE BERING WILL SEND A FRONT INTO THE
KODIAK AREA AND THEN SLIDE SOUTH OF THE RIDGE INTO THE GULF ON
WEDNESDAY. THIS SHOULD RESULT IN RAIN ACROSS KODIAK FOR TUESDAY
AND WEDNESDAY, THOUGH IT IS A FACTOR IN INCREASING THE RIDGING FOR
OTHER PARTS OF SOUTHCENTRAL ON WEDNESDAY.
THIS PATTERN WILL ALSO KEEP THE NORTHEASTERN COPPER BASIN IN THE
PERIPHERY OF THE RIDGE WHICH MEANS THE POTENTIAL FOR
THUNDERSTORMS DUE TO ENOUGH RIDGING TO WARM UP THE SURFACE BUT NOT
ENOUGH SUBSIDENCE TO KEEP THEM FROM DEVELOPING. THEREFORE, THERE
WILL BE A CHANCE FOR THUNDERSTORMS NEAR THE ALASKA RANGE FROM
APPROXIMATELY PAXSON AND EASTWARD THE NEXT FEW AFTERNOON AND
EVENINGS.
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (DAYS
1 THROUGH 3: THIS MORNING THROUGH WEDNESDAY)...
THE MATURE LOW THAT HAS EMERGED OFF OF THE KAMCHATKA PENINSULA
CONTINUES TO PUSH EASTWARDS INTO THE WESTERN BERING, WITH ITS WARM
FRONT REACHING COASTAL SOUTHWEST ALASKA THIS MORNING AND ITS
TRAILING COLD FRONT DRAPED ACROSS THE SOUTHERN BERING AND
ALEUTIANS. THE ARRIVAL OF THE FRONT OVERNIGHT HAS BEEN AS
ADVERTISED WITH GUSTY SOUTHERLY WINDS AND ABUNDANT RAINFALL AS THE
SYSTEM CONTINUES TO BE SUPPLIED WITH PLENTIFUL MOISTURE FROM THE
TROPICAL PACIFIC.
ONGOING MODERATE TO HEAVY RAIN AT TIMES IS EXPECTED TO CONTINUE
FOR THE KUSKOKWIM DELTA COAST THROUGH THIS EVENING. RAIN WILL
CONTINUE TO WORK INTO BRISTOL BAY AND THE INTERIOR KUSKOKWIM DELTA
THROUGH THIS MORNING AND EARLY AFTERNOON. REINFORCING SHOTS OF
WARM AIR AND MOISTURE GET PULLED NORTHWARD INTO THE WESTERN AND
CENTRAL ALEUTIANS AS WELL AS THE PRIBILOF ISLANDS THIS MORNING
THROUGH TONIGHT. THIS ACTIVITY MOVES EAST TO THE EASTERN ALEUTIANS
AND SOUTHERN ALASKA PENINSULA (AKPEN) FOR TUESDAY AS THE INITIAL
FRONT BEGINS TO OCCLUDE AND MOVES FURTHER INLAND TO THE KUSKOKWIM
VALLEY. THE HEAVIEST RAIN LOOKS TO FALL ACROSS THE KUSKOKWIM DELTA
COAST THIS MORNING AND AFTERNOON AND ACROSS THE BRISTOL BAY
COAST, SOUTHERN AKPEN, AND WESTERN KUSKOKWIM VALLEY FOR TUESDAY.
IN ADDITION TO THE WIDESPREAD RAIN, GUSTY SOUTH-SOUTHWESTERLY
WINDS WILL ALSO ACCOMPANY THIS SYSTEM. GUSTS OF 35 TO 40 KT ARE
POSSIBLE BY THIS AFTERNOON FOR UNALASKA BAY AND COLD BAY. SIMILAR
GUSTS ARE ALSO POSSIBLE ACROSS KUSKOKWIM BAY, LIKELY RESULTING IN
ROUGH SEAS ALONG WITH THE POTENTIAL OF LOCALIZED AREAS OF COASTAL
EROSION. THE GUSTY WINDS WILL EXTEND INTO THE KUSKOKWIM DELTA,
WITH WINDS GUSTING AS HIGH AS 40 MPH FOR BETHEL.
RAIN CONTINUES TO LINGER ACROSS MAINLAND SOUTHWEST THROUGH
TUESDAY EVENING WITH THE HEAVIEST ALONG THE SOUTHERN AKPEN AS THE
LOW TRACKS TO THE EASTERN BERING. THE DEVELOPMENT OF A TRIPLE
POINT LOW TO THE SOUTH OF THE AKPEN WILL CONTINUE TO BRING
ADDITIONAL RAINFALL TO THE AKPEN, BRISTOL BAY, AND SOUTHWEST
ALASKA COAST INTO WEDNESDAY.
A RIDGE BUILDS IN BEHIND THE LOW ACROSS THE REST OF THE BERING
WITH QUIETER WEATHER ACROSS THE WESTERN AND CENTRAL ALEUTIANS
TUESDAY EVENING AS THE EASTERN ALEUTIANS CONTEND WITH NORTHERLY
FLOW AND RAIN SHOWERS DOWNSTREAM OF THE RIDGE. AREAS OF FOG ARE
LIKELY TO REDEVELOP FOR THE WESTERN BERING AND ALEUTIANS,
UNDERNEATH THE RIDGE.
-JH/TM
.LONG TERM FORECAST (DAYS 4 THROUGH 7: THURSDAY THROUGH
SUNDAY)...
THE LONG TERM FORECAST REMAINS ON TRACK. A STRONG UPPER RIDGE
WILL BUILD IN OVER THE NORTHERN HALF OF ALASKA THROUGH THE END OF
THE WEEK. THIS, COMBINED WITH A PERSISTENT UPPER LOW IN THE
ALEXANDER ARCHIPELAGO WILL CHANNEL EASTERLY WAVES THROUGH
SOUTHCENTRAL ALASKA. THIS PATTERN WILL FAVOR SHOWERS AND
THUNDERSTORMS IN THE COPPER RIVER BASIN AND THE LOWER KUSKOKWIM
VALLEY FOR THE END OF THE WEEK INCLUDING THE 4TH OF JULY. THE
ANCHORAGE AND MAT-SU VALLEY REGIONS MAY SEE SHOWERS WITH CHANCES
INCREASING THE FURTHER NORTH YOU GO. THE KUSKOKWIM DELTA AND THE
WESTERN PARTS OF BRISTOL BAY WILL ALSO RECEIVE SHOWERS, BUT DUE
TO THE MARINE INFLUENCE, THUNDERSTORMS ARE UNLIKELY. THE EASTERN
PART OF THE GULF COAST FROM CORDOVA EAST WILL RECEIVE PERIODIC
BOUTS OF RAINFALL AS THE WAVES PASS THROUGH. MEANWHILE, THE BERING
WILL START WITH SLIGHT RIDGING ON THURSDAY, ALLOWING FOR LESS
ACTIVE WEATHER. HOWEVER, BY FRIDAY, A LARGE LOW WILL SWING IN FROM
THE WEST, INCREASING WIND SPEEDS AND RAIN CHANCES INTO THE
WEEKEND.
THE WEEKEND SEES THE UPPER RIDGE IN THE NORTH FLATTEN OUT. THERE
IS QUITE A BIT OF UNCERTAINTY IN HOW EXACTLY THIS WILL PLAY OUT,
BUT MOST GUIDANCE DOES AGREE THAT THE RIDGE WILL REDUCE AT SOME
POINT. AS FOR OUR FORECAST AREA, THE AFOREMENTIONED LARGE RIDGE IN
THE BERING WILL SWING OVER INTO THE GULF OF ALASKA BY SUNDAY,
BRINGING INCREASED WIND SPEEDS AND RAIN CHANCES FOR FIRST THE GULF
COAST, THEN THE REST OF INLAND SOUTHCENTRAL BY MONDAY. THERE IS
GOOD MODEL AGREEMENT ON THIS SCENARIO WITH THE MAIN DIFFERENCE
BEING THE EXACT TRACK OF THE LOW WHEN IT MOVES INTO THE GULF OF
ALASKA.
.AVIATION...
PANC...MONDAY MORNING WILL SEE SOME OCCASIONAL MVFR CEILINGS AS
PERSISTENT SOUTH-TO-SOUTHWEST LOW LEVEL WINDS WILL ALLOW CLOUDS TO
CONTINUE TO PACK UP ALONG THE CHUGACH MOUNTAINS AND WESTWARD TO
OVER THE AIRPORT. A WEAK SHORT WAVE IS TRACKING FROM NORTHEAST TO
SOUTHWEST OVER THE CHUGACH THIS MORNING AS WELL. THIS COULD BRING
IN SOME SHOWERS TO THE AIRPORT AS IT MOVES OVER, BUT VISIBILITIES
ARE EXPECTED TO REMAIN VFR DESPITE ANY SHOWERS.
CEILINGS SHOULD RISE AS THE DAY PROGRESSES, BUT A SOLID INCREASE
IN CEILINGS IS NOT LIKELY UNTIL SOMETIME ON TUESDAY.
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