845
FXAK68 PAFC 020111
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
511 PM AKDT TUE APR 1 2025
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3:
TONIGHT THROUGH FRIDAY)...
IT'S BECOME A REMARKABLY WARM SPRING DAY FOR A NUMBER OF SPOTS
ACROSS SOUTHCENTRAL THANKS TO A COMBINATION OF STRONG UPPER LEVEL
RIDGING MOVING OVERHEAD AND MOSTLY CLEAR SKIES (ASIDE FROM THE
COPPER VALLEY) AND GUSTY OFFSHORE WINDS OUT OF FAVORED GAPS ALONG
THE KENAI PENINSULA AND KODIAK ISLAND. BOTH SEWARD AND KODIAK
HAVE MANAGED TO SOAR ABOVE 60F AS GUSTY NORTH TO NORTHWEST WINDS
CAUSE DOWNSLOPE WARMING OFF OF TERRAIN AND INCREASE MIXING OF WARM
AIR ALOFT UNDER THE RIDGE IN PLACE. EVEN MUCH OF ANCHORAGE IS
SEEING THE FIRST DAY OF THE SEASON REACHING INTO THE 50S WITH
AMPLE SUNSHINE THIS AFTERNOON.
THE PATTERN WILL SHIFT SLOWLY AS THE LONGWAVE RIDGE GRADUALLY
SHIFTS MORE INTO THE GULF WEDNESDAY, THEN TOWARDS THE ALASKA
PANHANDLE AND NORTHWEST CANADA ON THURSDAY. AS THE HIGH SHIFTS
EASTWARDS, FLOW WILL BECOME MORE SOUTHWESTERLY ON WEDNESDAY,
PUTTING AN END TO THE GUSTY OFFSHORE GAP WINDS ALONG PARTS OF THE
GULF COAST. THE PRESSURE GRADIENT DRIVING THESE WINDS WILL
ESSENTIALLY REVERSE BY WEDNESDAY NIGHT AS A COASTAL RIDGE BUILDS
ALONG THE NORTH GULF COAST AND OVER PRINCE WILLIAM SOUND. THIS
COULD HELP A WEAK TURNAGAIN ARM WIND DEVELOP THAT COULD BEND INTO
WEST ANCHORAGE LATE WEDNESDAY NIGHT INTO THURSDAY MORNING BEFORE A
DOWN-INLET GRADIENT PULLS THE TURNAGAIN ARM JET BACK AWAY FROM
TOWN LATER ON THURSDAY MORNING.
FROM THURSDAY NIGHT INTO FRIDAY, AN EXPANSIVE NORTH PACIFIC LOW
DRIFTING SLOWLY NORTH WILL PUSH A GALE FORCE FRONT ACROSS THE
GULF, WITH THE BOUNDARY THEN STALLING CLOSE TO THE GULF COAST BY
FRIDAY AFTERNOON. SOUTHEAST WINDS ACROSS THE KENAI PENINSULA AND
ALONG THE TURNAGAIN ARM WILL STRENGTHEN SIGNIFICANTLY ALONG THE
TURNAGAIN ARM AS THE FRONT APPROACHES, WITH GUSTS AS STRONG AS 35
TO 50 MPH POSSIBLE FROM THURSDAY EVENING THROUGH AT LEAST FRIDAY
EVENING. STRONGER WINDS WILL LIKELY MOSTLY STAY OUT OF THE
ANCHORAGE BOWL, EXCEPT POSSIBLY FOR A SHORT WINDOW DURING PEAK
DAYTIME HEATING ON BOTH THURSDAY AFTERNOON AND FRIDAY AFTERNOON,
WHERE BOUNDARY LAYER INSTABILITY COULD BE ENOUGH TO MIX EASTERLY
WINDS ALOFT DOWN OFF OF THE HILLSIDE.
THE OTHER SIDE OF THIS FRONTAL SYSTEM OF COURSE WILL BE LIGHT TO
MODERATE RAINFALL AND MOUNTAIN SNOWFALL QUICKLY FILLING IN ACROSS
THE PRINCE WILLIAM SOUND REGION AND EASTERN KENAI PENINSULA
THURSDAY NIGHT INTO FRIDAY. SNOW LEVELS INITIALLY COULD BE LOW
ENOUGH FOR WET, SLUSHY SNOW THROUGH TURNAGAIN PASS, BUT WARMING
TEMPERATURES SHOULD TRANSITION SNOW OVER TO RAIN EVEN AT PASS
LEVEL BY FRIDAY AFTERNOON. THOMPSON PASS WILL HAVE THE BEST CHANCE
FOR SEEING SEVERAL INCHES OF ACCUMULATING SNOW THROUGH THE END OF
THE WEEK WHERE SNOW LEVELS COULD STAY LOW ENOUGH FOR ALL SNOW FOR
MUCH OF THIS EVENT.
-AS
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (DAYS
1 THROUGH 3: TODAY THROUGH WEDNESDAY)...
AN ELONGATED FRONT, STRETCHED FROM NUNIVAK ISLAND TO AMCHITKA, IS
STEADILY ADVANCING EASTWARD ACROSS THE BERING AND ALEUTIAN CHAIN.
MEANWHILE, A WEAKENING RIDGE OVER PORTIONS OF SOUTHWEST ALASKA
CONTINUES TO SHIFT SOUTHEASTWARD, OUT OF THE AREA. WIDESPREAD
AREAS OF FOG ACROSS THE EASTERN ALEUTIANS, ALASKA PENINSULA AND
COASTAL SOUTHWEST ALASKA ARE BREAKING DOWN THIS EVENING, HOWEVER
THERE IS THE POTENTIAL FOR AREAS OF FOG TO RETURN IN SIMILAR AREAS
WEDNESDAY MORNING. A TROUGH DRIVING THE FRONT OVER THE BERING
WILL PUSH INTO THE KUSKOKWIM COAST LATER THIS EVENING AND WILL
LIKELY CONTRIBUTE TO ADDITIONAL PERIODS OF REDUCED VISIBILITY FROM
LIGHT PRECIPITATION. AREAS FURTHER SOUTH ACROSS THE GREATER
BRISTOL BAY REGION HAVE REMAINED LARGELY DRY AND ARE FORECAST TO
STAY DRY INTO WEDNESDAY.
THROUGH WEDNESDAY, THE FRONT IS EXPECTED TO SLOW, SOMEWHAT
ANCHORING OVER THE CENTRAL/EASTERN ALEUTIANS TO THE PRIBILOFS,
PROMOTING A LIGHT RAIN/SNOW MIX AND STEADY NORTHERLY WINDS.
INFLUENCE FROM THE FRONT'S NORTHEASTERN EXTENT OVER THE KUSKOKWIM
DELTA WILL WEAKEN THROUGH WEDNESDAY, PROVIDING A REPRIEVE FROM THE
PRECIPITATION IN THE AREA FOR THE TIME BEING. ALONG WITH THE
RETURN OF FOG TO AREAS OF SOUTHWEST AND THE ALEUTIANS, WEDNESDAY
WILL BE LARGELY BENIGN, LEADING TO A STARK PATTERN SHIFT BEGINNING
EARLY THURSDAY MORNING.
LATE WEDNESDAY NIGHT, A ROBUST NORTH PACIFIC LOW WILL ADVANCE INTO
OUR AREA, MERGING WITH THE REMNANTS OF THE FRONT ACROSS THE BERING
AND AMPLIFYING THE PATTERN. AS THE LOW CONTINUES TO PUSH NORTHWARD
TOWARD THE ALASKA PENINSULA, NORTHERLY WINDS WILL INCREASE
SIGNIFICANTLY ACROSS THE EASTERN BERING AND ACROSS THE EASTERN
ALEUTIANS INCLUDING UNIMAK ISLAND/PASS. WINDS THROUGH GAPS WILL BE
STRONG BY THURSDAY AFTERNOON, REACHING STORM-FORCE ALONG THE
SOUTHERN SIDE OF THE EASTERN ALEUTIANS. GIVEN THE STRONG NORTHERLY
FLOW, TEMPERATURES ARE EXPECTED TO SETTLE NEAR FREEZING AT SEA-
LEVEL IN PLACES SUCH AS DUTCH HARBOR AND AKUTAN. THIS SYSTEM WILL
ALSO BE BRINGING WITH IT A SIGNIFICANT SHOT OF MOISTURE ALLOWING
FOR THE POTENTIAL OF HEAVY SNOW. UNALASKA, AKUTAN, AND NIKOLSKI
ARE CURRENTLY EXPECTED TO SEE THE WORST CONDITIONS FROM THIS
SYSTEM. AS SUCH, A WINTER STORM WATCH HAS BEEN ISSUED FOR THE
EASTERN ALEUTIANS BEGINNING THURSDAY MORNING AND LASTING THROUGH
SATURDAY MORNING.
SIMILARLY TO THE NORTHEAST OVER THE COASTAL KUSKOKWIM DELTA
INCLUDING KIPNUK AND NUNIVAK ISLAND, THE RESURGENCE OF WINDS AND
SNOW ALONG THE FRONTAL BOUNDARY SHOW POTENTIAL TO DRIVE BLIZZARD
CONDITIONS. A WINTER STORM WATCH HAS ALSO BEEN ISSUED FOR THIS
AREA FROM THURSDAY MORNING THROUGH SATURDAY AFTERNOON. THE
HEAVIEST SNOWFALL RATES AND STRONGEST WINDS ARE EXPECTED THURSDAY
EVENING THROUGH FRIDAY. SNOW AND GUSTY WINDS WILL TAPER OFF
BEGINNING LATE FRIDAY FROM SOUTH TO NORTH ALONG THE COAST AS THE
FRONT MOVES INTO THE EASTERN BERING. SNOW AND BLOWING SNOW IS ALSO
POSSIBLE FOR COMMUNITIES SOUTH AND EAST OF KIPNUK. HOWEVER,
BLIZZARD CONDITIONS ARE NOT EXPECTED FOR THESE LOCATIONS.
PLEASE REFERENCE THESE WATCHES AND STAY TUNED TO THE FORECAST AS
WE HONE IN ON THE POTENTIAL IMPACTS OF THIS STRONG LATE WINTER
SYSTEM.
LONG TERM FORECAST (DAYS 4 THROUGH 7: SATURDAY TO TUESDAY)
SOME INCREASING AMPLITUDE COMES WITH THE CHANGES ON THE ALASKA
WEATHER MAP THROUGH THE FORECAST PERIOD. THE UPPER LEVEL EASTERN
BERING TROUGH SLIPS INTO THE CENTRAL ALASKA MAINLAND FOR TUESDAY.
AN UPPER LEVEL CLOSED LOW SOUTH OF ALASKA PENINSULA MOVES INTO THE
SOUTHERN GULF OF ALASKA AND CONSOLIDATES ITS LINK WITH THE
MAINLAND TROUGH BY TUESDAY. AN UPPER RIDGE OVER THE WESTERN
CANADIAN PROVINCES ADJUSTS TO THE MOVEMENT AND SHORTWAVES ROTATING
THROUGH THE PATTERN, WHILE A SECOND UPPER RIDGE BUILDS OVER MOST
OF THE BERING THROUGH THE PERIOD. A FORECAST BLEND OF THE GFS AND
ECMWF MAINTAINS GOOD CONTINUITY OVER THE FEATURES' STRENGTH AND
MOVEMENT THROUGH THE WEEKEND, BUT THE GFS SLIDES TO THE SOUTH WITH
THE GULF OF ALASKA LOW BY TUESDAY.
A MODERATELY STRONG SURFACE LOW SOUTH OF THE AKPEN PUSHES ACROSS
THE SOUTHERN GULF OF ALASKA THROUGH TUESDAY. LOCALLY HEAVY RAINS
AND GALE FORCE WINDS SPAN FROM THE AKPEN ACROSS KODIAK ISLAND
THROUGH SUNDAY. HIGH END GALES ARE EXPECTED THROUGH BAYS AND
PASSES. THE RAIN AND GUSTY WINDS SPREAD OVER THE SOUTHCENTRAL
ALASKA COASTS TO THE CANADIAN BORDER THROUGH TUESDAY. LOCALLY
HEAVY SNOW IS EXPECTED OVER HIGHER TERRAIN INLAND MONDAY AND
TUESDAY. RAIN AND SNOW EXTENDS FROM THIS LOW INTO SOUTHWEST
ALASKA, WITH GUSTY WINDS FROM NUNIVAK ISLAND INTO THE EASTERN
ALEUTIANS. OUT WEST, A WELL DEVELOPED LOW AND FRONT APPROACHES
THE WESTERN AND CENTRAL ALEUTIANS, BRINGING RAIN AND GUSTY WINDS
THROUGH MONDAY, WITH MOST OF MORE SIGNIFICANT WEATHER REMAINING
OFFSHORE THROUGH TUESDAY.
- KUTZ
AVIATION
PANC...VFR CONDITIONS AND LIGHT WINDS WILL PERSIST UNTIL LATE WEDNESDAY
NIGHT WHEN THE TURNAGAIN ARM JET DEVELOPS AND COULD BEND GUSTY
SOUTHEASTERLY WINDS TOWARDS THE TERMINAL.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page