917
FXAK68 PAFC 291256
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
456 AM AKDT SAT MAR 29 2025
SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3)
EARLY THIS MORNING, RADAR IS SHOWING A LINE OF VERY LIGHT SNOW
DEVELOPING FROM FIRE ISLAND SOUTHWESTWARD TO KENAI AND TO ANCHOR
POINT. THIS IS THE RESULT OF THE UPPER LEVEL TROUGH DIGGING
SOUTHWARD AND INTERACTING WITH THE LOW-TO-MID LEVEL MOISTURE
ADVECTING INTO THE AREA FROM THE SOUTHEAST DUE TO A LOW THAT
RESIDES JUST EAST OF KODIAK. THE UNCERTAINTY OF THE LOCATION OF
WHERE THIS FEATURE WOULD DEVELOP HAS BEEN DISCUSSED IN THE PAST
TWO MORNING DISCUSSIONS AND WE NOW KNOW. HOWEVER, THERE IS DRY AIR
IN THE LOWER 5000 FT OF THE ATMOSPHERE, SO MOST OF THE SNOW WILL
LIKELY SUBLIMATE (AND BECOME VIRGA) ON THE WAY DOWN. THEREFORE
ONLY A DUSTING IS EXPECTED EVEN WHERE THE SNOW IS ABLE TO REACH
THE GROUND. FARTHER TO THE NORTHEAST ALONG THIS UPPER LEVEL
TROUGH THERE IS ALSO SOME VERY LIGHT SNOW THAT HAS DEVELOPED
THROUGH CHICKALOON PASS AND INTO THE FAR WESTERN COPPER RIVER
BASIN, BUT THIS WILL ALSO BE VERY LIGHT. GETTING BACK TO THE LOW
NEAR KODIAK, THIS LOW IS BRINGING SOME SNOW AND GUSTY WINDS TO THE
ISLAND THIS MORNING, BUT AS WITH ALL THE SNOWFALL BEING
REFERENCED SO FAR, IT WILL NOT LAST LONG INTO THE DAY. THAT IS DUE
TO THE KODIAK LOW MOVING SOUTHEAST AND RAPIDLY WEAKENING AS WILL
THE UPPER LEVEL TROUGH. BY THIS AFTERNOON, THERE SHOULD BE
CLEARING SKIES MOVING INTO THE AREA FROM THE NORTHWEST WHICH WILL
PERSIST INTO SUNDAY.
A SHORT WAVE MOVING IN ADVANCE OF AN UPPER LEVEL RIDGE WILL MOVE
ACROSS THE NORTHERN PART OF THE REGION, BUT IT IS EXPECTED TO
MAINLY BRING IN MID-LEVEL CLOUDS. THERE IS A CHANCE FOR SOME SNOW
ALONG THE ALASKA RANGE SUNDAY NIGHT INTO EARLY MONDAY MORNING WITH
THIS SHORT WAVE, BUT THAT IS ABOUT ALL THE EXCITEMENT IT WILL
PROVIDE FOR SOUTHCENTRAL. THIS UPPER LEVEL RIDGE WILL REMAIN WITH
ITS CORE OVER THE ALEUTIANS AND ALASKA PENINSULA. THIS WILL BRING
RATHER STRONG NORTHWESTERLY WINDS ALOFT INTO SOUTHCENTRAL AND WARM
AIR ALOFT. THIS IS LIKELY TO BE A DIRTY RIDGE WITH MID-TO-HIGH
LEVEL CLOUDS MOVING THROUGH SOUTHCENTRAL SO THERE MAY BE A BIT
MORE CLOUDINESS ASSOCIATED WITH IT THAT INITIALLY THOUGH.
INCREASING NORTHWESTERLY WINDS ARE EXPECTED ON MONDAY WITH THE
STRONGEST WINDS OVER THE KODIAK AREA INCLUDING THE BARREN
ISLANDS.
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (DAYS
1 THROUGH 3: TODAY THROUGH MONDAY)...
THE PRIMARY DRIVING FEATURE FOR SENSIBLE CONDITIONS ACROSS THE
BERING AND SOUTHWEST IS AN ANOMALOUSLY STRONG, BLOCKING HIGH
PRESSURE NOW EXTENDING FROM THE NORTH PACIFIC INTO MUCH OF THE
BERING SEA. THIS RIDGE AXIS WILL CONTINUE TO BUILD IN PLACE OVER
THE WEEKEND AND EXPAND NORTHEASTWARDS WITH TIME, LEADING TO VERY
LITTLE CHANGE IN THE GENERAL PATTERN ALREADY IN PLACE INTO EARLY
NEXT WEEK. IN THE NEAR TERM THROUGH TODAY, THE MOST IMPACTFUL
WEATHER WILL BE THE ONGOING STRONG AND GUSTY GAP WINDS ALONG AND
SOUTH OF THE AKPEN AND PARTS OF THE EASTERN ALEUTIANS. IN THE
PAST 12 HOURS, THE STRONGEST OBSERVED GUSTS HAVE BEEN 68 MPH AT
KING COVE, 52 MPH AT DUTCH HARBOR, 48 MPH AT COLD BAY, AND 45 MPH
AT BOTH AKUTAN AND SAND POINT. GAP WINDS FROM THE EASTERN
ALEUTIANS TO AKPEN SHOULD WEAKEN FURTHER FROM SUNDAY INTO MONDAY
AS FLOW AROUND THE STRONG RIDGE TO THE WEST BECOMES MORE
NORTHEASTERLY AND AS COLD AIR ADVECTION CEASES.
LOOKING OUT MORE BROADLY, THE NEXT FEATURE TO WATCH WILL BE A
WEAK SHORTWAVE TROUGH EXPECTED TO ROUND THE TOP OF THE RIDGE
TONIGHT, THEN DRIVE SOUTH INTO PORTIONS OF SOUTHWEST LATER TODAY.
PARTS OF THE KUSKOKWIM DELTA STILL LOOK ON TRACK TO SEE LIGHT
SNOWFALL AS MOISTURE STREAMS IN FROM THE NORTHWEST AHEAD OF THE
APPROACHING WAVE. AREAS BETWEEN BETHEL AND ANIAK WILL LIKELY SEE
ABOUT A HALF INCH OR LESS OF SNOW BEFORE PRECIPITATION MOSTLY
SHUTS OFF TONIGHT. WEAK PERTURBATIONS WILL CONTINUE TO RIDE
AROUND THE RIDGE INTO SOUTHWEST FROM SUNDAY TO MONDAY, SUPPORTING
CONTINUED CHANCES FOR LIGHT SNOW OVER MAINLY HIGHER TERRAIN ALONG
THE KUSKOKWIM MOUNTAINS. AREAS OF FOG, DRIZZLE AND FREEZING
DRIZZLE COULD DEVELOP NEAR THE KUSKOKWIM DELTA COAST AS LOW LEVEL
MOISTURE BUILDS UP UNDER A STRONG SUBSIDENCE INVERSION UNDER THE
STRONG UPPER RIDGE MOVING INTO PLACE. ACROSS MUCH OF THE BERING
SEA AND ALEUTIANS, FOG AND LOW STRATUS WILL BECOME INCREASINGLY
WIDESPREAD THROUGH EARLY NEXT WEEK AS MOISTURE SIMILARLY BUILDS UP
IN THE MARINE LAYER UNDER THE WARMER AIR ALOFT.
-AS/KC
LONG TERM FORECAST (DAYS 4 THROUGH 7: TUESDAY TO FRIDAY)
THE BROAD UPPER LEVEL RIDGE PATTERN ACROSS THE ALASKA REGION
BREAKS DOWN BRIEFLY AS A MODERATE AMPLITUDE TROUGH PASSES FROM
SIBERIA TO THE WESTERN ALASKAN COAST BY THE END OF THE WEEK. THE
UPPER RIDGE HOLDS ON ACROSS THE EASTERN NORTH PACIFIC TO THE
CANADIAN ARCTIC, AND REBUILDS OVER KAMCHATKA BY FRIDAY. A NORTH
PACIFIC UPPER LOW MOVES IN SOUTH OF THE ALASKA PENINSULA THROUGH
FRIDAY. THE GFS / ECMWF / CANADIAN MODEL BLEND THAT CARRIED GOOD
CONTINUITY THROUGH THE FORECAST BEGINS TO DISASSEMBLE, WITH AN
ENSEMBLE MIX PICKING UP THE SLACK AT THE END OF THE FORECAST.
GALE FORCE WINDS WITH POSSIBLE STORM FORCE GUSTS EXITS THE
PACIFIC SIDE OF THE AKPEN FROM THE SHUMAGIN ISLANDS TO KAMISHAK
BAY AND THE BARREN ISLAND THROUGH EARLY WEDNESDAY. A SECOND AREA
OF GALES MOVES OVER THE NORTHERN BERING THROUGH LATE WEDNESDAY.
SNOW SPREADS OVER INTERIOR ALASKA AHEAD OF THE BERING FRONT, AND
EXITS THE STATE EARLY WEDNESDAY. A CENTRAL KAMCHATKA LOW EXTENDS A
FRONT ACROSS THE BERING WITH SNOW INTO THE INTERIOR AND SOUTHWEST
ALASKA, DIMINISHING BY FRIDAY. SNOW CHANGES TO RAIN WITH GUSTY
WINDS AS THE FRONT SLIDES OVER THE ALEUTIANS AND AKPEN THURSDAY. A
WELL DEVELOPED SOUTHERN KAMCHATKA LOW AND FRONT PUSHES LOCALLY
HEAVY RAINS INTO THE WESTERN ALEUTIANS THROUGH FRIDAY.
- KUTZ
.AVIATION...
PANC...VFR CONDITIONS AND LIGHT NORTHERLY WINDS ARE EXPECTED TO
PERSIST THROUGH SUNDAY MORNING.
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