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FXAK68 PAFC 281243
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
443 AM AKDT FRI MAR 28 2025
SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3)
FRIDAY IS STARTING OUT WITH HIGH PRESSURE ALOFT OVER SOUTHEAST
ALASKA AS WELL AS THE BERING SEA. IN BETWEEN THERE IS A TROUGH
ALOFT RUNNING FROM THE INTERIOR, OVER THE ALASKA/ALEUTIAN RANGES
TO KODIAK ISLAND AND SOUTHWARD. THIS IS BRINGING IN SOME HIGHER
CLOUDS TO SOUTHCENTRAL EARLY THIS MORNING WHICH WILL BE LOWERING
SOME THROUGH THE DAY AS SOME MOISTURE MOVES OFF THE GULF AND INTO
THE REGION. THIS CAN BE SEEN ON EARLY MORNING SATELLITE IMAGERY
WITH THE CLOUDS MOVING INTO IN FROM THE SOUTHEAST BETWEEN THESE
FEATURES. WHILE NOT OVERLY SIGNIFICANT WEATHER-WISE, THE HIGHER
CLOUDS REALLY STAND OUT ON THE IR SATELLITE AS THEY ROTATE
CLOCKWISE AROUND THE UPPER LEVEL HIGH. SURFACE FLOW REMAINS
NORTHERLY THROUGH THE REGION TODAY AS THE SURFACE HIGH PRESSURE IN
THE INTERIOR PERSISTS WITH WEAK LOW PRESSURE RESIDING IN THE GULF
OF ALASKA. THIS PATTERN WILL LEAD TO SOME NORTHERLY WIND GUSTS
PERSISTING THROUGH CHANNELED TERRAIN TODAY AND INTO TONIGHT.
THE UPPER LEVEL HIGH OVER SOUTHEAST WILL MOVE INTO SOUTHCENTRAL
TODAY AND SPLIT THE TROUGH. THE SOUTHERN PART OF THIS TROUGH WILL
MOVE SOUTHWARD AND DISSIPATE, BUT THE UPPER LEVEL TROUGH IN THE
INTERIOR WILL STRENGTHEN SOME AS IT DIGS SOUTHWARD OVERNIGHT. THIS
WILL INITIATE SOME PRECIPITATION AS THE UPPER TROUGH MEETS THE
MORE MOIST AIR FROM THE LOWER LEVEL SOUTHEAST FLOW. THIS IS WHERE
THE MAIN UNCERTAINTY COMES IN: HOW FAR SOUTH AND EAST WILL THE
TROUGH MOVE BEFORE IT CAUSES ENOUGH FOR THE PRECIPITATION? MODELS
ARE SHOWING THE MOST LIKELY PLACE TO BE IN THE EASTERN KENAI
PENINSULA AND THROUGH PRINCE WILLIAM SOUND. THE GFS AND ARW (ONE
OF THE HI-RES MODELS) BOTH BRING THE WESTERN EDGE OF THE PRECIP
RIGHT TO ANCHORAGE'S DOORSTEP SO THAT IS THE REASON FOR THE SLIGHT
CHANCE OF SNOW FOR LATE FRIDAY NIGHT INTO EARLY SATURDAY MORNING
IN THE LATEST FORECAST PACKAGE. MOST OF THE OTHER MODELS KEEP
THIS PRECIPITATION FARTHER EAST. ANOTHER CHANGE FROM YESTERDAY
MORNING'S FORECAST IS THAT IT LOOKS LESS LIKELY THAT ANY SNOW IN
THE COPPER RIVER BASIN WILL MAKE IT AS FAR NORTH AS GLENNALLEN. IF
IT DOES, IT WILL BE LIGHT. PRECIPITATION ALONG THE NORTH GULF
COAST AND PRINCE WILLIAM SOUND IS LIKELY THE BE A MIX OF RAIN AND
SNOW DEPENDING ON TIME OF DAY.
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (DAYS
1 THROUGH 3: FRIDAY THROUGH SUNDAY)...
FEW CHANGES TO THE FORECAST. MINIMAL EDITS WERE MADE TO THE
PREVIOUS FORECAST DISCUSSION, WHICH IS REPLICATED BELOW.
AN ALMOST COMPLETELY STEADY-STATE PATTERN IS EXPECTED TO PERSIST
INTO THE WEEKEND AS A STRONG, BLOCKING UPPER RIDGE AXIS EXPANDS
AND INTENSIFIES ACROSS THE WESTERN BERING SEA OVER THE NEXT FEW
DAYS. TO THE EAST OF THIS AREA OF HIGH PRESSURE, DRY AND COOL
NORTHERLY FLOW IS CONTINUING ACROSS SOUTHWEST, WHERE MOSTLY CLEAR
SKIES AND SEASONABLY COOL TEMPERATURES REMAIN IN PLACE. STRONG AND
GUSTY WINDS CONTINUE ACROSS THE EASTERN ALEUTIANS AND SOUTHERN
AKPEN, SUPPORTED BY A COMBINATION OF COLD AIR ADVECTION AND A
STRONG PRESSURE GRADIENT BETWEEN THE RIDGE OUT WEST AND A WEAK LOW
IN THE GULF. GALE FORCE WINDS WITH GUSTS UP TO STORM FORCE ALONG
AND JUST SOUTH OF THE AKPEN WILL CONTINUE FOR THE FORESEEABLE
FUTURE AS THIS SUPPORTING LARGE SCALE PATTERN REMAINS FAIRLY
STAGNANT THROUGH THE WEEKEND. QUIET CONDITIONS WITH MUCH CALMER
WINDS WILL PERSIST FARTHER WEST ALONG MOST OF THE ALEUTIAN CHAIN
AND PRIBILOF ISLANDS.
OVER THE WEEKEND ACROSS SOUTHWEST, CLOUD COVER WILL BEGIN TO
INCREASE AS MOISTURE WRAPS EAST AROUND THE CREST OF THE RIDGE
FROM A FRONTAL SYSTEM MOVING ACROSS THE NORTHERN BERING SEA. THERE
WILL BE SOME CHANCE FOR AREAS OF LIGHT PRECIPITATION TO FILL IN
ACROSS PARTS OF THE KUSKOKWIM DELTA AS THIS MOISTURE AXIS STREAMS
INTO PLACE BETWEEN SATURDAY AND SUNDAY, BUT ANYTHING THAT DOES
REACH THE GROUND WILL LIKELY REMAIN VERY LIGHT. THERE IS A SMALL
CHANCE FOR SOME OF THIS TO FALL AS A MIX OF SNOW, FREEZING RAIN
AND SLEET. THIS POTENTIAL IS DUE TO THE COMBINATION OF A STRONG
WARM NOSE PRODUCED BY SUBSIDENCE WARMING UNDER THE RIDGE AND
SURFACE TEMPERATURES THAT COULD HOVER AT OR JUST BELOW FREEZING
THROUGH SUNDAY. AGAIN, ANY MIXED PRECIPITATION THAT DOES DEVELOP
IS EXPECTED TO REMAIN LIGHT.
-AS/KC
LONG TERM FORECAST (DAYS 4 THROUGH 7: MONDAY TO THURSDAY)
THE STEADY CHANGES IN THE OVERALL PATTERN CONTINUE THROUGH THE
FORECAST PERIOD. THE UPPER LEVEL BERING RIDGE FLATTENS OUT, BUT
REMAINS QUITE BROAD THROUGH THE WEEK. A COUPLE OF UPPER TROUGHS
MOVE OVER THE RIDGE IN THE ARCTIC. AN UPPER TROUGH EXTENDING FROM
A LOW IN THE CANADIAN ARCTIC CURVES BACK INTO THE EASTERN GULF OF
ALASKA THROUGH MIDWEEK. A GFS / ECMWF / CANADIAN MODEL BLEND
CONTINUES GOOD CONTINUITY WITH THE DETAILS THROUGH MOST OF THE
FORECAST, AND SWITCHES TO AN ENSEMBLE BLEND FOR THE END OF THE
WEEK TO KEEP HOLD OF THE FORECAST FEATURES.
AREAS OF LOCALLY MODERATE SNOW MOVE OVER INTERIOR ALASKA AND
EXITS THE EASTERN BORDER THROUGH TUESDAY. A NEW FRONT INTRODUCES
MORE SNOW AND GUSTY WINDS ALONG THE WEST COAST LATE TUESDAY,
SPREADING TO THE INTERIOR AND ALASKA PENINSULA THROUGH THURSDAY.
SNOW CHANGES TO RAIN AROUND THE WESTERN YUKON AND KUSKOKWIM
VALLEYS COASTAL AREAS BEFORE DISSIPATING EARLY WEDNESDAY. A WELL
DEVELOPED CENTRAL KAMCHATKA LOW AND FRONT BRINGS LOCALLY MODERATE
SNOW CHANGING TO RAIN AND GUSTY WINDS INTO THE WESTERN ALEUTIANS
AND BERING TUESDAY, DIMINISHING WEDNESDAY OVER THE BERING.
- KUTZ
.AVIATION...
PANC...VFR CONDITIONS AND LIGHT NORTHERLY WINDS PERSIST THROUGH
SATURDAY MORNING.
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