459
FXAK68 PAFC 062354
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
354 PM AKDT TUE MAY 6 2025
SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3)
THE LOW IN THE GULF CONTINUES TO SLOWLY MOVE SOUTHEAST. DUE TO
THE ORIENTATION OF THE LOW, PRESSURE GRADIENTS ARE STILL FAVORABLE
FOR GUSTY SOUTHEASTERLY WINDS OUT OF GAPS IN THE ANCHORAGE,
MATANUSKA VALLEY, AND THE COPPER RIVER BASIN AREAS. WINDS ARE
QUITE LIGHT EVERYWHERE ELSE, INCLUDING IN THE MARINE AREAS WHERE
THEY ARE BREEZY. DUE TO AMPLE DAYTIME HEATING AND SOME MOISTURE,
CONVECTIVE SHOWERS WITH SOME ISOLATED LIGHTNING IS FORMING ON THE
WESTERN SLOPES OF MOUNTAINS IN THE MAT-SU VALLEYS, COPPER RIVER
BASIN, KENAI PENINSULA, AND EVEN NEAR BIRCHWOOD. THE REST OF
ANCHORAGE IS UNDER MORE OF A MARINE INFLUENCE AND IS MOSTLY CLEAR.
OUR FOCUS SHIFTS TO THE NORTH ON WEDNESDAY AS AN UPPER LEVEL LOW
SWEEPS IN FROM THE NORTHEAST ALONG THE ALASKA RANGE. THIS WILL
DRIVE UP PRECIPITATION CHANCES IN THE SUSITNA VALLEY AND THE
COPPER RIVER BASIN. THIS PRECIPITATION WILL BE STRATIFORM IN
NATURE, SO EXPECT WIDESPREAD LIGHT RAINFALL IN THESE REGIONS. THE
SYSTEM WILL ALSO ALLOW FOR MOSTLY CLOUDY SKIES DOWN TO ANCHORAGE
AND THE KENAI PENINSULA. THERE IS, HOWEVER, QUITE A BIT OF
UNCERTAINTY WITH THIS UPPER LEVEL LOW IN ITS TRACK AND ITS
STRENGTH. IF IT STAYS MORE TO THE NORTH, THERE WILL BE LOWER
CHANCES FOR PRECIPITATION AND LOWER CLOUD COVER IN THE
AFOREMENTIONED AREAS. WIND SPEEDS WILL NOT BE AFFECTED MUCH BY
THIS SYSTEM AND WILL REMAIN LIGHT IN MOST LOCATIONS.
REGARDLESS OF WHAT SCENARIO WINS OUT, THE LOW WILL DRIFT TO THE
WEST BY THURSDAY AND PRECIPITATION CHANCES WILL DIMINISH IN
RESPONSE. THE LOW IN THE GULF WILL STILL BE HANGING AROUND AND
WILL PUSH A SHORTWAVE UP TOWARD THE NORTHERN GULF, INCREASING WIND
SPEEDS TO SMALL CRAFT ALONG THE COAST THURSDAY INTO FRIDAY.
INLAND WINDS WILL REMAIN ON THE LIGHTER SIDE. PRECIPITATION
CHANCES ALONG THE COAST WILL INCREASE AS WELL WITH THIS WAVE.
CONVECTIVE SHOWERS WILL BE POSSIBLE AGAIN FOR THE WESTERN SLOPES
OF MOUNTAINS IN INLAND AREAS ON THURSDAY AND FRIDAY, BUT LIGHTNING
CHANCES WILL BE LOWER THAN TODAY (TUESDAY).
-JAR
SHORT TERM FORECAST SOUTHWEST ALASKA (TODAY THROUGH FRIDAY)
SYNOPTICALLY, THE STATIONARY LOW OFF THE COAST OF KODIAK ISLAND
AND THE EASTWARD-MOVING RIDGE OVER THE ALEUTIANS WILL CONTINUE TO
CAUSE IMPACTFUL WEATHER TO THE AREA THE NEXT 24 TO 36 HOURS.
AFTERWARD, A FRONT PROGRESSES THROUGH THE ALEUTIANS TOWARD THE SW
MAINLAND BRINGING RAIN, GUSTY WINDS AND WARMER TEMPERATURES.
THE BAND OF LATE MORNING RAIN SHOWERS FROM KASIGLUK TO BETHEL
SOUTHWESTWARD TO KONGIGANAK WILL CONTINUE TO MOVE SOUTHWESTWARD
THROUGH THIS EVENING. THIS BAND WILL BRING RAIN TO THE WESTERN COAST
AS FAR SOUTH AS GOODNEWS BAY BEFORE REACHING BRISTOL BAY OVERNIGHT.
IN ITS WAKE, NORTHEAST WINDS HAVE KEPT LOW CLOUDS OVER THE BETHEL
TO EEK AREA. THESE CONDITIONS WILL CONTINUE INTO TOMORROW
AFTERNOON OVER THE AREA. FARTHER SOUTH AND EAST, NORTHEASTERLY
WINDS CONTINUE TO BRING SCATTED RAIN SHOWERS TO DILLINGHAM NORTH
AND EAST TO SLEETMUTE SOUTH TO THE ALASKA PENINSULA. MULTIPLE
SHOWERS HAVE BEEN SEEN ON THE WEBCAMS IN THE ACROSS THE REGION
THIS AFTERNOON AT EGEGIK, DILLINGHAM, KOLIGANEK AND NONDALTON.
ISOLATED, WET THUNDERSTORMS WILL BE EMBEDDED IN THE WIDESPREAD
SCATTERED RAIN SHOWERS LATER THIS AFTERNOON AND EARLY EVENING
HOURS. A FEW STRIKES HAVE BEEN SEEN IN THE SLEETMUTE AREA ALREADY.
THE LIKELIHOOD OF AN ISOLATED WET THUNDERSTORM AND SCATTERED RAIN
SHOWER REMAINS TOMORROW AND THURSDAY TOO THOUGH MORE CONFINED TO
NEW STUYAHOK SOUTH TO IGIUGIG EASTWARD TO LAKE ILIAMNA AS THE
KODIAK LOW SLOWLY MOVES SOUTHEASTWARD.
NORTHERLY / NORTHWESTERLY WINDS WILL DIMINISH AS A WEAK RIDGE
BUILDS OVER THE EASTERN ALEUTIANS / BERING SEA INTO THURSDAY.
TODAY'S WIND GUSTS WERE STRONGEST IN THE COLD BAY TO NELSON LAGOON
AREA REACHING 40 MPH BUT HAVE SINCE DIMINISHED AND WILL REMAIN IN
THE 20 TO 25 MPH RANGE OVERNIGHT THROUGH TOMORROW EVENING. THE
LATE WEEK FRONT BRINGS RAIN, WARM TEMPERATURES AND GUSTY WINDS TO
THE ALEUTIANS. THE STRONGEST WINDS CONTINUE TO TREND TOWARD THE
PACIFIC OCEAN SIDE OF THE ALEUTIAN ISLANDS WITH STORM FORCE TO
GALE-FORCE WIND GUSTS.
-DJ
LONG TERM FORECAST (DAYS 4 THROUGH 7/SATURDAY THROUGH TUESDAY)
COMPARED TO YESTERDAY, MODEL GUIDANCE FOR THE DAY 4 THROUGH 7 TIME
PERIOD HAS TRENDED TOWARD A MORE AMPLIFIED UPPER LEVEL PATTERN.
MODEL SPREAD REMAINS QUITE LARGE WITH INDIVIDUAL STORMS AND
FEATURES, THOUGH THE LARGE SCALE EVOLUTION IS SIMILAR. STARTING
OUT ON SATURDAY, UPPER LEVEL RIDGING OVER SOUTHERN AK LOOKS
FAVORABLE TO PRODUCE A GOOD AMOUNT OF SUNSHINE, NORMAL TO ABOVE
NORMAL TEMPERATURES (IN THE 50S TO AROUND 60), AND MOSTLY DRY
CONDITIONS. MEANWHILE, A TROUGH WILL EXTEND FROM THE BERING SEA TO
THE GULF OF AK, WITH WEAK SURFACE LOWS LIKELY. MODEL SPREAD IS
PARTICULARLY LARGE WITH POSITION OF THE GULF LOW, WHICH CREATES
LOTS OF UNCERTAINTY IN THE WEATHER FOR KODIAK AND THE GULF COAST.
IN ANY CASE, ANY IMPACTS OF PRECIPITATION AND WIND WOULD BE SHORT-
LIVED. FOR NOW, THE FORECAST LEANS TOWARD THE ENSEMBLE MEAN WHICH
KEEPS THE BULK OF IMPACTS OFFSHORE.
AS WE CONTINUE THROUGH THE WEEKEND ATTENTION WILL SHIFT TO A
RAPIDLY DEEPENING LOW OVER THE NORTH-CENTRAL PACIFIC AND
ASSOCIATED AMPLIFICATION OF THE UPPER LEVEL FLOW. MODEL GUIDANCE
HAS TRENDED TOWARD A DEEPER LOW AND FURTHER WEST LOW TRACK, TAKING
THE LOW NORTHWARD INTO THE BERING SEA SOMETIME SUNDAY OR MONDAY.
EVEN WITH THE FASTEST OF SOLUTIONS, SOUTHERN ALASKA LOOKS MOSTLY
SUNNY AND DRY ON SUNDAY AS THE RIDGE BUILDING OUT AHEAD OF THE
PACIFIC LOW APPROACHES SOUTHERN AK. STRONG WINDS AND PRECIPITATION
WILL INITIALLY AFFECT THE BERING SEA AND ALEUTIANS. IN A CHANGE
FROM YESTERDAY, A FRONTAL SYSTEM WILL THEN DRIVE EASTWARD TOWARD
SOUTHERN AK, LIKELY BRINGING WINDS AND RAIN TO THE REGION MONDAY
THROUGH TUESDAY. WITH A LOW TRACK TO THE NORTHERN BERING SEA, WILL
NEED TO KEEP AN EYE ON POTENTIAL FOR STORM SURGE ALONG THE SW AK
COAST. UNSETTLED WEATHER WILL LIKELY CONTINUE BEHIND THE DEEP LOW,
WITH STRONG AND PROGRESSIVE UPPER LEVEL FLOW AND ADDITIONAL AREAS
OF CYCLOGENESIS (STORM DEVELOPMENT) OVER THE NORTH PACIFIC.
-SEB
AVIATION
PANC...VFR CONDITIONS WILL PERSIST. THE TURNAGAIN ARM WIND WILL
CONTINUE THROUGH THIS EVENING BEFORE WEAKENING IN THE LATE
EVENING. WINDS WILL THEN TURNING UP-INLET ON WEDNESDAY MORNING,
POTENTIALLY TURNING INTO A SEA BREEZE WEDNESDAY AFTERNOON. THERE
CURRENTLY IS A LOT OF UNCERTAINTY ON WEDNESDAY AS FAR
PRECIPITATION GOES. MODEL GUIDANCE IS VERY UNCERTAIN ABOUT A
DISTURBANCE OVER THE EASTERN INTERIOR OF ALASKA/CANADIAN YUKON
AND IT'S EXACT TRACK TOWARD THE SOUTHWEST. LIGHT RAIN (VFR) COULD
REACH AS FAR AS PANC ON WEDNESDAY MORNING.
MTL
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