300
FXAK68 PAFC 161312
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
412 AM AKST SUN FEB 16 2025
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA
(DAYS 1 THROUGH 3: TODAY THROUGH TUESDAY EVENING)...
THE FORECAST IS ON TRACK THIS MORNING AS AN OCCLUDED FRONT
ADVANCES TOWARD THE NORTHERN GULF FROM THE SOUTHEAST. ITS
ATTENDANT SURFACE LOW IS SITUATED SOUTHEAST OF KODIAK ISLAND THIS
MORNING AND IS ALSO TRACKING SLOWLY NORTHWEST TOWARD THE ISLAND.
MOISTURE IS STREAMING ALONG THE FRONT, WITH WIDESPREAD
PRECIPITATION OVER THE NORTHERN GULF AND ENTERING PRINCE
WILLIAM SOUND. DRIER AIR NEAR THE SURFACE AND A MORE EASTERLY FLOW
AHEAD OF THE FRONT HAS KEPT THE PRECIPITATION AWAY FROM THE PRINCE
WILLIAM SOUND COAST OVERNIGHT, BUT STRONGER RADAR RETURNS ARE
BEGINNING TO DEVELOP OVER THESE LOCATIONS AS OF 4 AM, SIGNALING A
LIKELY START TO THE EXPECTED RAIN/SNOW MIX BY SUNRISE.
FARTHER WEST, THE MOISTURE ADVECTION IS INTERACTING WITH A
LINGERING SURFACE TROUGH OVER COOK INLET AND A WEAK UPPER-LEVEL
WAVE. THE RESULT HAS BEEN BANDS OF LIGHT SNOW FROM ANCHORAGE
SOUTH TO HOMER OVERNIGHT. THESE BANDS WILL CONTINUE TO MOVE
NORTHWEST THIS MORNING ALONG WITH ITS UPPER-LEVEL SUPPORT.
PRECIPITATION ASSOCIATED WITH THIS SYSTEM WILL INITIALLY FALL AS A
MIX OF RAIN AND SNOW ALONG THE IMMEDIATE COAST, BUT IS STILL
EXPECTED TO CHANGE QUICKLY TO RAIN AS INCREASING EASTERLY WINDS
USHER IN WARMER AIR, PUSHING SNOW LEVELS TO AROUND 1,000 FT BY
BY LATE SUNDAY AFTERNOON. A FEW INCHES OF WET SNOW ARE POSSIBLE
FOR WHITTIER, PORTAGE, AND TURNAGAIN PASS BEFORE THE CHANGEOVER
TO RAIN.
THE SURFACE LOW ELONGATES AND MOVES TO NORTHERN KODIAK ISLAND THIS
AFTERNOON AS ITS FRONT STALLS ALONG THE COAST. A WEAK UPPER-LEVEL
WAVE ASSOCIATED WITH THE FRONT MAY HELP SPILL SOME PRECIPITATION
OVER THE KENAI AND CHUGACH MOUNTAINS LATER TODAY IN CONJUNCTION
WITH WARMER AIR ADVECTING ALOFT. THIS MAY RESULT IN A PERIOD OF
VERY LIGHT MIXED WINTRY PRECIPITATION FROM KENAI TO TALKEETNA
LATER TODAY AS TEMPERATURES HOVER IN THE UPPER 20S TO LOWER 30S.
THE SOUTHEASTERLY, CROSS-BARRIER FLOW THEN STRENGTHENS BEHIND THIS
WAVE, KEEPING CONDITIONS DRY ALONG THE LEE OF THE CHUGACH AND
KENAI MOUNTAINS OVERNIGHT SUNDAY AND INTO MONDAY. FOR COASTAL
LOCATIONS, PRECIPITATION WILL CONTINUE, BUT SHOULD BE MORE SHOWERY
IN NATURE. SNOW LEVELS WILL CONTINUE TO RISE, TO AROUND 1,600 FT
FOR MONDAY.
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.
-TM/DAN
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (DAYS
1 THROUGH 3: TONIGHT THROUGH MONDAY)...
THE COLD AND DRY PATTERN OVER SOUTHWEST ALASKA DRIVEN BY AN UPPER
LEVEL LOW WILL BEGIN TO STEADILY TRANSITION RELATIVELY WARMER AS
THE LOW EXITS TO THE NORTH, ALLOWING FOR WARMER AIR FROM THE SOUTH
TO MOVE IN. BY WEDNESDAY MORNING, LOW TEMPERATURES MAY RETURN UP
TO THE LOW 20S IN THE LOWER KUSKOKWIM VALLEY AND KUSKOKWIM DELTA.
INTERIOR SOUTHWEST SHOULD REMAIN DRY THROUGH MONDAY AS UPPER LEVEL
RIDGING CURRENTLY OVER THE BERING SEA AND EASTERN ALEUTIANS
SHIFTS EAST AND BUILDS OVER SOUTHWEST ALASKA ON SUNDAY. A FRONT
EXTENDING FROM ITS PARENT LOW SOUTH OF THE KAMCHATKA PENINSULA
WILL ALLOW FOR SHOWERY WEATHER TO CONTINUE FOR THE WESTERN AND
CENTRAL ALEUTIANS THROUGH SUNDAY AS IT LIFTS NORTHWARD INTO THE
BERING AND WEAKENS.
A STEADY STREAM OF SHORT WAVE ENERGY FROM THE NORTH PACIFIC WILL
CONTINUE TO KEEP THE WEATHER PATTERN ACTIVE ACROSS THE BERING SEA
AS A BROAD LOW PRESSURE SYSTEM REACHES THE SOUTHERN SHORES OF THE
ALEUTIAN CHAIN AND AKPEN MONDAY MORNING THROUGH MONDAY AFTERNOON.
WHILE THE PROGRESSION OF THE FRONT IN THE BERING REMAINS
UNCERTAIN, MUCH OF THE ALEUTIAN CHAIN WILL HAVE A CHANCE TO SEE
LIGHT RAIN THROUGH EARLY NEXT WEEK, WITH THE HEAVIEST RAIN
EXPECTED TO BE FOCUSED FOR THE EASTERN ALEUTIANS AND AKPEN AS THE
FRONT IS GENERALLY EXPECTED TO LIFT ACROSS SOUTHWEST ALASKA. THE
FRONT APPROACHING THROUGH TUESDAY MORNING WILL DRIVE THE
AFOREMENTIONED WARMING TREND ACROSS SOUTHWEST ALASKA HELPING TO
IMPROVE COLD WIND CHILL VALUES ACROSS THE REGION. THE
INTRODUCTION OF WARMER AIR TO SOUTHWEST WILL BE PART OF A SMALL
FRONTAL SYSTEM ADVANCING NORTHWARD, REACHING THE KUSKOKWIM DELTA
COAST BY WEDNESDAY AFTERNOON. THIS PRESENCE AND STRENGTH OF THIS
BOUNDARY IS NOT CERTAIN AMONGST THE MODEL SOLUTIONS, HOWEVER HAS
THE POTENTIAL TO BRING A BRIEF SHOT OF SNOWFALL TO THE AREA, AND
ALONG WITH THE GUSTY OFFSHORE FLOW, MAY DRIVE SOME BLOWING SNOW.
IMPACTS TO VISIBILITY ARE DIFFICULT TO TELL WITH THE MODEL
DISCREPANCIES, HOWEVER INITIALLY APPEARS TO NOT BRING ENOUGH
SNOWFALL TO PROVIDE SIGNIFICANT REDUCTIONS IN VISIBILITY. THIS
WOULD LIKELY BE A QUICK EVENT CONTAINED TO THE KUSKOKWIM DELTA
COASTLINE, INCLUDING KIPNUK, KWIGILLINGOK, AND MEKORYUK. A STRONG
PRESSURE GRADIENT WILL DRIVE LARGE SWATH OF NORTHEASTERLY GALES
ACROSS THE NORTHERN BERING SEA WILL PERSIST THROUGH TUESDAY.
-CL
.LONG TERM FORECAST (DAYS 4 THROUGH 7) WEDNESDAY THROUGH
SATURDAY...
THE BROAD UPPER LEVEL TROUGHING OVER SOUTHERN AND WESTERN PART OF
THE STATE WILL PERSIST. THIS COUPLED WITH THE MODERATELY STRONG
HIGH PRESSURE RIDGE ALONG THE STATE'S SOUTHEAST COASTLINE AND INTO
THE CENTRAL INTERIOR OF THE STATE WILL DOMINATE THE WEATHER
PATTERN THROUGH THE FORECAST PERIOD. EQUAL WEIGHT WAS GIVEN
BETWEEN THE GFS, EUROPEAN AND CANADIAN MODELS WITH THE UKMET BEING
THE CONSISTENT OUTLIER.
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. WITH A MORE SOUTHERLY
WIND PATTERN, TEMPERATURES WILL BE UNSEASONABLY WARM ACROSS MUCH
OF THE REGION WITH HIGHER PRECIPITATION AMOUNTS MAINLY FALLING AS
RAIN ALONG THE NORTHERN GULF COASTLINE AND THROUGH THE CENTRAL
ALEUTIANS WITH POTENTIALLY HEAVY SNOW ACCUMULATIONS IN THE HIGHER
COASTAL ELEVATIONS.
-DD
AVIATION
PANC...LIGHT NORTHERLY WINDS AND VFR CONDITIONS ARE EXPECTED TO
PERSIST, BUT THERE IS A LOW CHANCE (30%) FOR A BRIEF PERIOD OF
VERY LIGHT SNOW OR WINTRY MIX THIS EVENING AS SOME PRECIPITATION
MAY SPILL OVER THE CHUGACH MOUNTAINS.
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