638
FXAK68 PAFC 020125
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
525 PM AKDT TUE JUL 1 2025
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3: TODAY
THROUGH FRIDAY AFTERNOON)...
SOUTHCENTRAL ALASKA REMAINS IN A COL BETWEEN UPPER LEVEL RIDGING
TO THE NORTH AND SOUTH, AND UPPER LEVEL LOWS TO THE NORTHWEST AND
SOUTHEAST. THE MOST NOTABLE FEATURES ON SATELLITE ARE THE ABUNDANT
CUMULUS CLOUDS DEVELOPING ACROSS MAT-SU, THE ANCHORAGE BOWL, AND
COPPER RIVER BASIN IN RESPONSE TO DAYTIME HEATING. MEANWHILE, A
FRONT IS DRAPED ACROSS KODIAK ISLAND, WITH HIGHER CLOUDS PUSHING
NORTH ACROSS KENAI PENINSULA. GENERALLY, EXPECT THIS PATTERN TO
PERSIST IN THE COMING DAYS, WITH CLOUDIER AND WETTER CONDITIONS
OVER KODIAK ISLAND/SOUTHERN KENAI PENINSULA, AND WARMER AND MORE
CONVECTIVE CONDITIONS FOR THE REMAINDER OF SOUTHCENTRAL ALASKA.
NOT MUCH IN THE WAY OF SHOWERS OR THUNDERSTORMS ARE EXPECTED TODAY
AS THE RIDGE TO THE NORTH SUPPRESSES CONVECTION AND RELATIVELY
FAST MID-LEVEL FLOW SHEARS APART CELLS BEFORE THEY CAN BECOME
MORE ORGANIZED. HOWEVER, MUCH MORE WIDESPREAD SHOWERS AND ISOLATED
TO SCATTERED THUNDERSTORMS ARE FORECAST FOR TOMORROW AS A ROBUST
UPPER LEVEL SHORTWAVE MOVES SOUTH TO SOUTHWESTWARD ACROSS THE
SOUTHCENTRAL MAINLAND. SHORT-RANGE, HIGH RESOLUTION, CONVECTION
ALLOWING MODELS HAVE COME INTO MUCH BETTER AGREEMENT FOR TOMORROW,
INCREASING FORECAST CONFIDENCE. GENERALLY, EXPECT SHOWERS AND
THUNDERSTORMS TO BEGIN FIRING OFF TOMORROW AFTERNOON ALONG THE
ALASKA RANGE AT FIRST, THEN MOVE ACROSS THE COPPER RIVER BASIN
INTO THE TALKEETNA MOUNTAINS, WRANGELL MOUNTAINS, AND PERHAPS AS
FAR SOUTH AS THE CHUGACH RANGE. WITH DECENT MID-LEVEL FLOW, THERE
IS A CHANCE FOR THESE THUNDERSTORMS TO MAKE IT ACROSS THE
MOUNTAINS AND INTO PARTS OF THE MAT-SU VALLEYS. THE PRIMARY
CHALLENGE WILL BE DETERMINING HOW FAR THESE STORMS CAN DRIFT
BEFORE DAYTIME HEATING OR EVEN COOLER AIR ASSOCIATED WITH HIGH-
ELEVATION SNOW (OR THE STABLE MARINE LAYER) CAUSES THEM TO WEAKEN
AND DISSIPATE.
-KC
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (DAYS
1 THROUGH 3: TONIGHT THROUGH THURSDAY NIGHT)...
A MATURE LOW PRESSURE SYSTEM ORIGINATING IN THE BERING SEA
CONTINUES TO PUSH ONSHORE TO ALASKA'S WEST COAST. GUSTY SOUTHERLY
WINDS AND MODERATE TO HEAVY RAINFALL HAS BEEN PERSISTENT OVER THE
LAST 24 HOURS FROM THE ALASKA PENINSULA TO NORTON SOUND AS
ABUNDANT TROPICAL MOISTURE IS DRAWN NORTH ACROSS THE REGION. WELL
OVER AN INCH OF RAINFALL HAS FALLEN IN DILLINGHAM, BETHEL, AND
MANY OTHER LOCATIONS UNDER THIS LARGE SWATH OF MOISTURE. A
SHORTWAVE TROUGH DIVING SOUTH ACROSS THE CENTRAL ALEUTIANS TODAY
WILL AID IN PULLING THE PARENT LOW PRESSURE SYSTEM DOWN ACROSS
BRISTOL BAY TONIGHT AND INTO THE WESTERN GULF BY LATE TOMORROW.
CONTINUED SOUTHEASTERLY FLOW THROUGH THIS TIME PERIOD WILL ALLOW
HEAVY RAINFALL TO CONTINUE IN THE BRISTOL BAY REGION, PARTICULARLY
UPSLOPE ENHANCED TERRAIN ALONG THE ALASKA PENINSULA AND THE WOOD-
TIKCHIK MOUNTAINS. EXPECT ELEVATED WATER LEVELS IN RIVERS
SURROUNDING THE GREATER BRISTOL BAY AREA FOR THE NEXT SEVERAL DAYS
AS RECENT RAINS WORK DOWN THE WOOD-TIKCHIK LAKE SYSTEM.
PRECIPITATION WILL BEGIN DIMINISHING TOMORROW AFTERNOON AS THE LOW
MOVES SOUTH AND DOWNSLOPING FROM A SHIFT TO EASTERLY FLOW BEGINS
TO DRY OUT THE AREA. HIGH PRESSURE OVER NORTHERN ALASKA WILL AID
IN A DRYING TREND BY THURSDAY, CLEARING SKIES AND WARMING
TEMPERATURES IN THE KUSKOKWIM RIVER VALLEY FOR THE JULY 4TH
HOLIDAY.
FARTHER WEST, A HIGH PRESSURE RIDGE IS CURRENTLY BUILDING IN
BEHIND THE LOW AND WILL WORK EAST ACROSS THE ALEUTIAN CHAIN. AREAS
OF FOG ARE LIKELY TO REDEVELOP FOR THE BERING AND ALEUTIANS
BENEATH THE RIDGE, BEFORE THE FRONT OF A NEW LOW OUT OF KAMCHATKA
SWEEPS ACROSS THE WESTERN BERING THURSDAY MORNING. GUIDANCE IS NOT
YET IN FULL AGREEMENT AS TO THE EXACT STRENGTH AND POSITION OF
THIS SYSTEM, BUT ANOTHER ROUND OF WIDESPREAD RAIN AND ELEVATED
WINDS CAN BE EXPECTED TO MOVE ACROSS THE BERING THROUGH THURSDAY
NIGHT.
.LONG TERM FORECAST (DAYS 4 THROUGH 7: SATURDAY THROUGH
TUESDAY)...
THE LONG TERM FORECAST STARTS WITH A LARGE UPPER LOW IN THE
ALASKA PENINSULA REGION. THIS LOW WILL BRING HEAVY RAINFALL FOR
THE ALASKA PENINSULA AND PARTS OF BRISTOL BAY STARTING FRIDAY AND
CONTINUING THROUGH THE WEEKEND. THE LOW WILL ALSO DRIVE FRONTAL
SYSTEMS INTO THE GULF OF ALASKA ON SATURDAY. THIS BRINGS HEAVY
RAINFALL IN KODIAK ISLAND AND THE COASTAL REGIONS OF THE MAINLAND
THROUGH THE WEEKEND AND INTO THE WORKWEEK. INLAND AREAS INCLUDING
ANCHORAGE WILL SEE LESS OR NO RAINFALL DEPENDING ON DOWNSLOPING.
THE COPPER RIVER BASIN AND THE TALKEETNA MOUNTAINS COULD SEE
THUNDERSTORMS DURING THE WEEKEND DUE TO HIGHER INSTABILITY AND
EASTERLY WAVES. THERE IS HIGH UNCERTAINTY WITH THE FORECAST FROM
MONDAY ONWARD WITH GUIDANCE SHOWING MANY DIFFERENT SCENARIOS.
SOME GUIDANCE HAS MULTIPLE LOWS FORMING IN THE WEST AND TRACKING
INTO THE GULF OF ALASKA, WHERE OTHERS HAVE THE PREVIOUS LOW
STALLING OUT IN THE SOUTHERN PART OF THE GULF. THE ONLY THING THAT
CAN BE REASONABLY AFFIRMED AT THIS POINT IS RAINFALL FOR KODIAK
ISLAND AND THE SOUTHCENTRAL COASTLINE. AS FOR SOUTHWEST ALASKA
FOR NEXT WEEK, AGAIN, UNCERTAINTY RULES THE DAY. HOWEVER, SOME
KIND OF COL OR WEAK FLOW MAY SET UP AND LEAD TO DRIER CONDITIONS
IN THE MAINLAND. THE BERING WILL SEE SOME KIND OF LOW MOVE THROUGH
WITH RAIN CHANCES AND GUSTY WINDS POSSIBLE.
-JAR
.AVIATION...
PANC...SOUTHEASTERLY FLOW IS NOW ENTRENCHED ALOFT, WHICH MEANS
CIGS SHOULD REMAIN VFR THROUGH THE TAF PERIOD. TURNAGAIN WINDS
HAVE ALREADY DEVELOPED AND WILL CONTINUE THROUGH EARLY WEDNESDAY
MORNING AND WILL RETURN WEDNESDAY AFTERNOON.
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