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FXAK68 PAFC 040031
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
431 PM AKDT TUE JUN 3 2025
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3:
TONIGHT THROUGH FRIDAY)...
A STRONG SHORTWAVE TROUGH LIFTING ACROSS SOUTHCENTRAL ALASKA THIS
AFTERNOON IS PRODUCING MODERATE RAINFALL IN THE SUSITNA VALLEY
AND ALONG THE NORTH GULF COAST. LIGHT RAIN SHOWERS ALSO ASSOCIATED
WITH THE SHORTWAVE LIFT FROM THE KENAI PENINSULA TOWARD ANCHORAGE
AND THE MATANUSKA VALLEY THIS EVENING, WHICH COULD LEAD TO AROUND
A TENTH OF AN INCH OF PRECIPITATION. A COASTAL RIDGE ENHANCED BY
THIS TROUGH IS ALSO CAUSING GUSTY SOUTHEASTERLY GAP WINDS THROUGH
TURNAGAIN ARM, THE KNIK RIVER VALLEY, AND COPPER RIVER VALLEY.
THESE WINDS DIMINISH IN INTENSITY THIS EVENING AS THE SHORTWAVE
LIFTS NORTH.
TONIGHT, A LOW TRACKS APPROACHES KODIAK ISLAND FROM THE NORTH
PACIFIC AND HEADS TO THE BARREN ISLANDS FOR WEDNESDAY AFTERNOON.
THIS LOW BRINGS ANOTHER ROUND OF LIGHT TO MODERATE RAINFALL FOR
SOUTHCENTRAL THROUGH THURSDAY. THE MAIN FRONT REACHES THE
SOUTHCENTRAL MAINLAND WEDNESDAY MORNING, WITH SOUTHEASTERLY FLOW
ALOFT CONTRIBUTING TO A DOWNSLOPE HOLE EXTENDING ACROSS PORTIONS
OF THE KENAI PENINSULA, ANCHORAGE, AND NORTH TO PALMER. THERE IS
SOME UNCERTAINTY IN THE STRENGTH OF THE DOWNSLOPING, PARTICULARLY
AS A RESULT OF HOW MUCH WINDS NEAR THE SURFACE BEND DOWN-INLET AS
A RESULT OF THE LOW TRACKING NEAR KENNEDY ENTRANCE. A MIDDLE OF
THE ROAD SOLUTION WITH WINDS BENDING SOMEWHAT DOWN- INLET WOULD
LEAD TO LIGHT, INTERMITTENT RAINFALL IN THESE TYPICAL DOWNSLOPING
AREAS THROUGH THE DAY ON WEDNESDAY. MEANWHILE, HEAVIER RAINFALL
OCCURS CLOSER TO AND OVER COOK INLET, MUCH OF THE SUSITNA VALLEY,
AND ALONG THE NORTH GULF COAST. WHILE THIS WOULD KEEP SOUTHERLY
GAP WINDS GOING THROUGH THE KNIK AND COPPER VALLEYS, THE TURNAGAIN
WIND WOULD LIKELY BEND MOSTLY OUT OF ANCHORAGE BY MIDDAY. THIS
SOLUTION IS ALSO FAVORED BECAUSE PRECIPITATION AND THICK CLOUD
COVER WILL PREVENT THE NECESSARY HEATING IN THE SUSITNA VALLEY
THAT WOULD KEEP THE TURNAGAIN ARM WIND MORE NEUTRAL OR BENDING
NORTH INTO ANCHORAGE.
THE LOW TRACKS ALONG THE EASTERN KENAI INTO PRINCE WILLIAM SOUND
FOR WEDNESDAY NIGHT, WHICH WILL ALLOW SOUTHERLY GAP WINDS TO
DIMINISH AND BECOME LIGHT NORTHERLY AS THE COASTAL RIDGE IS
DESTROYED. THIS WILL ALSO ELIMINATE DOWNSLOPING AND RAINFALL
INTENSIFIES/FILLS IN FOR A SHORT TIME OVERNIGHT OVER THE INTERIOR
KENAI, ANCHORAGE, AND MATANUSKA VALLEY. IN TOTAL, EXPECTING AROUND
0.30 TO 0.50 INCHES OF RAIN FOR THESE AREAS, WITH HIGHER VALUES IN
THE SUSITNA VALLEY. AROUND ANOTHER INCH OF RAINFALL IS FORECAST FOR
SEWARD WITH GENERALLY SOUTH TO SOUTHEAST FLOW WEDNESDAY THROUGH
WEDNESDAY NIGHT. THE COPPER RIVER BASIN REMAINS DRY UNTIL EARLY
THURSDAY MORNING, WHEN DOWNSLOPING ACROSS THE CENTRAL CHUGACH
MOUNTAINS DIMINISHES AND LIGHT RAINFALL CAN BEGIN.
SOME CLEARING ON THURSDAY OVER THE WESTERN SUSITNA VALLEY AND THE
KENAI PENINSULA COULD LEAD TO ENOUGH INSTABILITY FOR ISOLATED
THUNDERSTORMS. OTHERWISE, EXPECT THE TROUGH TO LINGER OVER
SOUTHCENTRAL THROUGH FRIDAY KEEPING TEMPERATURES GENERALLY
MODERATED WITH RAIN SHOWERS POSSIBLE. HOWEVER, EXPECT A GRADUAL
DRYING AND WARMING TREND THROUGH THE END OF THE WEEK.
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS
(DAYS 1 THROUGH 3: TODAY THROUGH THURSDAY EVENING)...
A WEAKENING LOW MOVING OVER THE MAINLAND WILL CONTINUE TO BRING
SCATTERED RAIN SHOWERS AND CONTINUED CLOUD COVER THROUGH THURSDAY
EVENING. HIGH PRESSURE BUILDS IN ACROSS THE ALEUTIANS BY THURSDAY
EVENING.
RAIN SHOWERS WERE ABUNDANT THIS MORNING AND AFTERNOON AS A BERING
SEA LOW CONTINUES TO MOVE OVER THE MAINLAND. TWELVE HOURS
PRECIPITATION AMOUNTS THROUGH 4:00PM TODAY RANGE FROM A FEW
HUNDREDTHS IN THE AK PEN AND EASTERN ALEUTIANS TO OVER HALF AN
INCH ACROSS AN AREA FROM JUST NORTH OF DILLINGHAM NORTHWARD TO
SLEETMUTE. A FEW BREAKS IN THE CLOUDS HAVE OCCURRED FROM ANIAK TO
LIME VILLAGE THIS AFTERNOON AND WITH COOLER AIR ALOFT AND
TEMPERATURES IN THE MIDDLE 50S, THE LIKELIHOOD FOR ISOLATED
THUNDERSTORM / LIGHTNING DEVELOPMENT CHANCE REMAINS BETWEEN 10%
AND 30%. THE SAME LIGHTNING CHANCES EXIST TOMORROW AFTERNOON AND
EVENING IN THIS AREA, TOO.
NORTHERLY THEN NORTHWESTERLY WIND FLOW WILL DOMINATE THE MAINLAND
AND ALEUTIANS AS THE LOW MOVES INTO INTERIOR ALASKA. THIS WILL
CONTINUE TO BRING COOLER AIR AND KEEP TEMPERATURES IN THE LOW TO
MIDDLE 50S THROUGHOUT THE DAY TOMORROW DESPITE PEAKS OF SUN
THROUGH MOSTLY OVERCAST SKY. TOMORROW, A WEAK, FAST-MOVING LOW
SOUTH OF THE AK PEN WILL BRING INCREASED GAP WINDS TOMORROW
AFTERNOON AND EVENING FOR THE CENTRAL AND EASTERN ALEUTIANS AND
THE ALASKA PENINSULA WITH GUSTS RANGING FROM 20 TO 30 KNOTS.
IN THE WAKE OF A THIRD LOW MOVING EAST OF THE PRIBILOFS AND
THROUGH BRISTOL BAY THURSDAY, HIGH PRESSURE BUILDS INTO THE
ALEUTIANS BY THE END OF THIS WEEK.
-JOHNSTON
.LONG TERM FORECAST (DAYS 4 THROUGH 7: SATURDAY THROUGH
TUESDAY)...
THE PERSISTENT LONGWAVE TROUGH ACROSS THE EASTERN BERING SEA AND
ALEUTIANS CONTINUES TO WEAKEN AND MIGRATE EASTWARD. SEVERAL
EMBEDDED SHORTWAVES ROTATING AROUND THE MAIN TROUGH AXIS WILL
TRACK ACROSS ALASKAN PENINSULA, SOUTHCENTRAL AND THE GULF OF
ALASKA, WHICH WILL CONTINUE TO SUPPORT COOLER AND WETTER THAN
AVERAGE WEATHER CONDITIONS FOR THE FORECAST PERIOD. HIGH PRESSURE
RIDGES INTO THE BERING SEA THROUGH TUESDAY.
-DD
AVIATION
PANC...
WINDS THROUGH THE TAF PERIOD WILL BE GENERALLY SOUTHEASTERLY
AROUND 10-20 KTS. THE HIGHER GUSTS TO 40 KT OCCURRING THIS
AFTERNOON SHOULD DIMINISH OVER THE NEXT FEW HOURS. EXPECT ANY
RAIN THIS AFTERNOON INTO WEDNESDAY MORNING TO BE ON THE LIGHT
SIDE, SO VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THEN.
HOWEVER, THE RAIN SHOULD BECOME HEAVIER TOMORROW MORNING AND COULD
DROP CEILINGS TO MVFR.
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