278
FXAK68 PAFC 180245
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
545 PM AKST MON FEB 17 2025
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA
(DAYS 1 THROUGH 3: TONIGHT THROUGH THURSDAY)...
COASTAL SOUTHCENTRAL CONTINUES TO EXPERIENCE RAIN AND HIGHER
ELEVATION SNOW AS A SHORTWAVE MOVES NORTHWARD TOWARDS THE
INTERIOR. THE WESTERN SUSITNA VALLEY AND ALASKA RANGE WILL SEE AN
UPTICK IN PRECIPITATION ONCE AGAIN THIS EVENING AS THE SHORTWAVE
OVER THE COASTLINE MOVES CLOSER TO THAT PART OF THE FORECAST
AREA.
THE SURFACE TROUGH AND UPPER-LEVEL SHORTWAVE OVER THE
SOUTHCENTRAL COAST WILL HELP REINFORCE MOISTURE ADVECTION AND
SOUTHEASTERLY WINDS ALOFT. THE RESULT WILL BE AN UPTICK IN
PRECIPITATION ALONG THE COAST AS WELL AS UPSLOPE AREAS ALONG THE
ALASKA RANGE. WITH SNOW LEVELS STAYING ABOVE 1,500 FT FOR THE
NEXT 24-48 HOURS, ACCUMULATING SNOWFALL WILL REMAIN CONFINED TO
THE HIGHER ELEVATIONS. SNOW MAY MIX WITH RAIN AT LOWER ELEVATIONS
ALONG THE COAST LATE TONIGHT INTO EARLY TUESDAY DUE TO A QUICK
PUSH OF COLDER AIR OVERNIGHT BEFORE TEMPERATURES PUSH BACK TO
AROUND 40F FOR TUESDAY FOR PLACE LIKE WHITTIER, PORTAGE, AND
SEWARD.
THE CHALLENGE IN THE SHORT TERM WILL BE THE EXTENT OF
PRECIPITATION SPILLING OVER THE CHUGACH AND KENAI MOUNTAINS LATER
THIS MORNING AND AGAIN LATE TONIGHT AND INTO EARLY TUESDAY. CHANCES
ARE SLIM TO NONE FOR THIS FORECAST PACKAGE; HOWEVER, IF ANY
PRECIPITATION DOES SPILL OVER, IT WILL LIKELY FALL AS A VERY LIGHT
WINTRY MIX, SIMILAR TO THE PLETHORA OF PRECIPITATION TYPES
OBSERVED FROM KENAI TO ANCHORAGE AND TALKEETNA YESTERDAY.
ANOTHER FRONTAL SYSTEM LIFTS NORTHWARD ACROSS THE GULF FOR
TUESDAY. THIS WILL SPREAD ANOTHER ROUND OF PRECIPITATION FROM
KODIAK ISLAND TO THE NORTH GULF COAST AND PRINCE WILLIAM SOUND
THROUGH THE DAY. MORE SEA-LEVEL RAIN WITH SNOW IN THE MOUNTAINS
CAN BE EXPECTED WITH THIS SYSTEM. INLAND AREAS IN THE LEE OF THE
MOUNTAINS ALSO LOOK TO REMAIN ON THE DRIER SIDE AS WELL. THE STORY
REMAINS THE SAME FOR WEDNESDAY AS EAST-SOUTHEAST FLOW CONTINUES
OFF THE GULF AND PRINCE WILLIAM SOUND WHICH WILL KEEP UPSLOPE
PRECIPITATION GOING AS WELL AS DOWNSLOPE DRYING IN THE LEE OF THE
MOUNTAIN RANGES. A MORE COMPACT SURFACE TROUGH PASSING OVER
SOUTHCENTRAL WEDNESDAY NIGHT-THURSDAY HAS THE POTENTIAL TO CARRY
OVER MORE WIDESPREAD BUT LIGHT PRECIPITATION, ESPECIALLY FOR
LOCATIONS ALONG THE COPPER RIVER BASIN.
-BS/TM/DAN
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (DAYS
1 THROUGH 3: TONIGHT THROUGH THURSDAY)...
A COMPACT UPPER LEVEL LOW CURRENTLY MOVING INLAND OVER THE
KUSKOKWIM DELTA REGION HAS SHIFTED THE PATTERN OVER SOUTHWEST
ALASKA TO A RELATIVELY WARMER AND MORE MOIST AIRMASS, BRINGING A
WAVE OF SNOW, FREEZING RAIN, AND RAIN OVER BRISTOL BAY THROUGHOUT
THIS AFTERNOON. A CHANCE OF SNOW AND A FREEZING RAIN/SNOW MIX
REMAINS THROUGH THIS EVENING FOR BRISTOL BAY WEST OF DILLINGHAM.
AS SUCH, A WINTER WEATHER ADVISORY REMAINS IN EFFECT FOR BRISTOL
BAY WEST OF DILLINGHAM FOR FREEZING RAIN WITH THE POTENTIAL FOR
SNOW AND BLOWING SNOW LARGELY ALONG THE WESTERN CAPES OF THE
REGION THROUGH MIDNIGHT TONIGHT. AS THE SYSTEM ADVANCES
NORTHWESTWARD OVER THE KUSKOKWIM DELTA THROUGHOUT TONIGHT AND INTO
TOMORROW MORNING, THE AXIS OF STRONGEST MOISTURE WILL HAVE
WEAKENED, BUT WITH OFFSHORE WINDS STILL FAIRLY GUSTY, SNOW AND
BLOWING SNOW IS POSSIBLE TUESDAY MORNING THROUGH TUESDAY
AFTERNOON, REDUCING VISIBILITY AT TIMES MAINLY IN AREAS ALONG AND
NEAR THE COASTLINE. THIS FRONT ADVANCING NORTHWESTWARD WILL ALSO
BRING A BRIEF WAVE OF SNOW SHOWERS TO THE PRIBILOFS BEGINNING
TUESDAY AFTERNOON, COMING TO AN END BY TUESDAY NIGHT. SOME AREAS
OF BLOWING SNOW ARE POSSIBLE WITH THIS WAVE, HOWEVER SIGNIFICANT
REDUCTIONS IN VISIBILITY IS NOT EXPECTED AT THIS TIME.
THE REMAINDER OF THE PERIOD WILL LARGELY BE CHARACTERIZED BY A
STEADY STREAM OF SHORTWAVE ENERGY FROM THE NORTH PACIFIC, KEEPING
THE WEATHER PATTERN ACTIVE ACROSS THE BERING SEA AND BRINGING
WARMER TEMPERATURES ACROSS THE ALEUTIANS AND SOUTHWEST ALASKA. A
BROAD LOW PRESSURE SYSTEM IS SET TO REACH THE SOUTHERN SHORES OF
THE ALEUTIAN CHAIN AND AKPEN THIS EVENING, BRINGING A CHANCE OF
LIGHT RAIN SHOWERS THROUGH THE PERIOD TO MANY OF THE ALEUTIAN
ISLANDS, WITH THE HEAVIEST RAIN EXPECTED TO BE FOCUSED ALONG THE
EASTERN ALEUTIANS AND AKPEN TONIGHT THROUGH WEDNESDAY MORNING. AS
THE LOW TRACKS NORTHWESTWARD ACROSS THE ALEUTIANS AND INTO THE
SOUTHERN BERING SEA THROUGHOUT THE DAY ON WEDNESDAY, THE PRIBILOFS
WILL LIKELY SEE AN ADDITIONAL ROUND OF SNOW BEFORE TRANSITIONING
TO A RAIN/SNOW MIX BY WEDNESDAY EVENING. BY THURSDAY MORNING,
ANOTHER LOW MOVING UP FROM THE NORTH PACIFIC WILL SKIRT SOUTH OF
THE AKPEN AND ENTER THE WESTERN GULF, CONTINUING A PATTERN OF
SHOWERY WEATHER FOR THE AKPEN AND WARM, SOUTHEASTERLY FLOW INTO
SOUTHWEST ALASKA FOR THE END OF THE PERIOD.
-JH
LONG TERM FORECAST (DAYS 4 THROUGH 7) FRIDAY THROUGH MONDAY
THE PERSISTENT BROAD UPPER LEVEL TROUGHING OVER THE BERING SEA
AND ALEUTIANS, COMBINED WITH THE STRONG UPPER LEVEL RIDGING OVER
MUCH OF THE ALASKAN MAINLAND AND ALONG THE PANHANDLE, WILL
CONTINUE TO DOMINATE THE WEATHER PATTERN THROUGH THE FORECAST
PERIOD. EQUAL WEIGHT WAS GIVEN BETWEEN ALL OF THE GLOBAL MODELS
WHICH HAVE COME INTO RELATIVE AGREEMENT WITH THE LARGER FEATURES.
HOWEVER, THERE IS SOME UNCERTAINTY ABOUT TIMING AND INTENSITY OF
THE UPPER LEVEL SHORTWAVES AND ASSOCIATED WEAK SURFACE LOWS.
THIS PATTERN WILL ALLOW FOR SMALL, FAST MOVING SHORTWAVE TROUGHS
AND ASSOCIATED SURFACE FRONTS TO QUICKLY MOVE ACROSS THE ALEUTIAN
ISLANDS AND COASTAL SOUTH CENTRAL REGIONS. THIS STUBBORN WEATHER
PATTERN WILL BRING A MORE SOUTHERLY WIND PATTERN AND UNSEASONABLY
WARMER TEMPERATURES ACROSS MUCH OF THE REGION WITH HIGHER
PRECIPITATION AMOUNTS FALLING MAINLY AS RAIN ALONG THE NORTHERN
GULF COASTLINE AND THROUGH THE CENTRAL ALEUTIANS. THERE IS A
POTENTIAL FOR HEAVY SNOW ACCUMULATIONS IN THE HIGHER COASTAL
ELEVATIONS.
-DD
AVIATION
PANC...LIGHT NORTHERLY WINDS AND VFR CONDITIONS ARE EXPECTED TO
PERSIST.
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