544
FXAK68 PAFC 290127
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
427 PM AKST FRI NOV 28 2025
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3:
TONIGHT THROUGH MONDAY)...
AN UPPER LEVEL SHORTWAVE TROUGH STRETCHING FROM THE WESTERN
ALASKA RANGE TO THE NORTHERN GULF CONTINUES TO MAKE STEADY
NORTHEAST PROGRESS INTO SOUTHCENTRAL THIS AFTERNOON. A SWATH OF
MOISTURE HAS MOVED UP INTO THE COPPER BASIN, WHERE FORCING AND
LIFT AHEAD OF THE INCOMING TROUGH ARE SUPPORTING WIDESPREAD LIGHT
SNOWFALL. FARTHER SOUTH, WARMER TEMPERATURES ARE YIELDING MOSTLY
COLD RAIN NEAR VALDEZ AND CORDOVA NEAR SEA LEVEL. BEHIND THE
TROUGH PASSAGE, THE WESTERN HALF OF SOUTHCENTRAL IS CLEARING OUT
AS A TRANSIENT UPPER RIDGE BEGINS TO BUILD INTO PLACE FROM
SOUTHWEST. PATCHY AREAS OF FOG HAVE DEVELOPED WHERE CALM WINDS AND
CLEAR SKIES HAVE HELPED THE NEAR SURFACE AIR RADIATE AND COOL TO
SATURATION. SO FAR, THIS HAS BEEN MOSTLY CONCENTRATED ACROSS THE
WESTERN KENAI PENINSULA. HOWEVER, AREAS FARTHER NORTH INTO
ANCHORAGE COULD EASILY FOG UP LATER THIS EVENING AS TEMPERATURES
COOL OFF A FEW DEGREES UNDER CLEAR SKIES AND LIGHT NORTHEAST
WINDS.
SATURDAY WILL MARK THE BEGINNING OF WHAT COULD TRULY BE DESCRIBED
AS A PROLONGED STRETCH OF WEATHER CHAOS. A STRONG WARM FRONT
ASSOCIATED WITH A LARGE LOW MOVING OVER THE NORTH PACIFIC IS
EXPECTED TO LIFT ACROSS THE GULF THROUGHOUT THE DAY, SENDING A
RENEWED SURGE OF MOISTURE AND LIFT STRAIGHT NORTH INTO
SOUTHCENTRAL. PRECIPITATION WILL OVERSPREAD MUCH OF THE OUTLOOK
AREA FROM SOUTH TO NORTH, FIRST REACHING KODIAK AND THE KENAI
PENINSULA EARLY IN THE MORNING, THEN SPREADING INTO THE INTERIOR
LATER IN THE DAY. A NOSE OF WARM AIR WILL MOVE IN ALOFT AS
TEMPERATURES ABOVE FREEZING STREAM NORTHWEST OVERTOP OF COOLER
TEMPERATURES IN PLACE ACROSS THE MAT-SU, ANCHORAGE AND WESTERN
KENAI PENINSULA RIGHT AROUND THE SAME TIME PRECIPITATION MOVING IN
AHEAD OF THE FRONT ARRIVES. THIS WILL CREATE A FAVORABLE
TEMPERATURES PROFILE FOR A WINTRY MIX OF SLEET, SNOW AND FREEZING
RAIN, ROUGHLY ALONG AN AXIS FROM ANCHOR POINT UP TO WILLOW AND
PALMER. WINTER WEATHER ADVISORIES ARE NOW SET TO GO INTO EFFECT
MIDDAY SATURDAY FOR THIS ENTIRE CORRIDOR.
ACROSS THE WINTER WEATHER ADVISORY AREAS, ICING AMOUNTS DO NOT
LOOK LIKELY TO BE ALL THAT SIGNIFICANT (NO MORE THAN 0.10") DUE
TO A COUPLE LIMITING FACTORS. FIRST OFF, INCREASING EASTERLY FLOW
WILL INCREASE DOWNSLOPE DRYING WITH TIME, LIMITING PRECIPITATION
INTENSITY. SECONDLY, EAST TO NORTHEAST WINDS WILL PICK UP SHARPLY
AT THE SURFACE BY SATURDAY EVENING AS A NORTHEAST TO SOUTHWEST
PRESSURE GRADIENT TIGHTENS AHEAD OF THE APPROACHING FRONTAL WAVE.
THIS WILL TEND TO INCREASE MIXING WITH TIME, ALLOWING TEMPERATURES
TO WARM A FEW DEGREES ABOVE FREEZING ACROSS MOST OF THE MAT
VALLEY, ANCHORAGE AND WESTERN KENAI PENINSULA FROM SATURDAY NIGHT
INTO EARLY SUNDAY. HOWEVER, THERE COULD BE A FEW COLD POCKETS THAT
LINGER INTO SUNDAY WHERE WINDS DO NOT MATERIALIZE, SUCH AS EAST
ANCHORAGE AND THE SOUTHERN END OF THE SUSITNA VALLEY. THIS COULD
ALLOW ISOLATED AREAS TO STILL SEE OCCASIONAL PERIODS OF FREEZING
RAIN LINGERING INTO MUCH OF SUNDAY.
LOOKING MORE INTO THE START OF NEXT WEEK, THE ACTIVE AND WARM
PATTERN SHOWS NO SIGNS OF ABATING. FROM SUNDAY INTO MONDAY, A
SHORTWAVE TROUGH AND ATTENDANT SURFACE LOW WILL MOVE NORTH INTO
THE EASTERN GULF AS THE FRONT MOVES INTO THE GULF COAST AND
WEAKENS. MODELS HAVE STRUGGLED MIGHTILY TO HONE IN ON THE TRACK OF
THIS SYSTEM, THOUGH THERE HAS BEEN A FAIRLY DISTINCT WEST SHIFT
FOR THE EXPECTED TRAJECTORY OF THIS SYSTEM. THE CONSENSUS IS THAT
THE LOW WILL STALL JUST SOUTH OF THE THE KENAI PENINSULA, THEN
POSSIBLY SHIFT MORE NORTHEAST TOWARDS PRINCE WILLIAM SOUND AS THE
UPPER TROUGH CONTINUES TO LIFT NORTH SOMEWHERE OVER THE EASTERN
HALF OF SOUTHCENTRAL. THIS COULD ACTUALLY FAVOR A PERIOD OF
ACCUMULATING WET SNOW ACROSS THE WESTERN KENAI PENINSULA UP INTO
ANCHORAGE AND THE MATANUSKA VALLEY, DEPENDING ON EXACTLY WHERE THE
UPPER TROUGH TRACKS AND HOW MUCH TEMPERATURES CAN COOL BACK DOWN
IN THE LOWER LEVELS AS PRECIPITATION MOVES BACK IN FROM THE WEST.
IT IS WORTH EMPHASIZING, HOWEVER, THAT THIS IS A COMPLEX PATTERN
WITH A LOT OF ROOM FOR MORE CHANGES TO HOW THINGS EVOLVE. BE SURE
TO MONITOR THE FORECAST FOR UPDATES AS WE CONTINUE TO FOLLOW THIS
VERY ACTIVE PATTERN INTO EARLY NEXT WEEK.
-AS
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (DAYS
1 THROUGH 3)...
**KEY MESSAGE: A WINTER STORM WATCH HAS BEEN ISSUED FOR THE
KUSKOKWIM DELTA AND KUSKOKWIM VALLEY FROM LATE SATURDAY NIGHT
THROUGH TUESDAY AFTERNOON FOR UP TO 2" OF SNOWFALL AND UP TO
0.25" OF ICE ACCUMULATION.**
DIVING INTO THE DETAILS, SATELLITE IMAGERY REVEALS A RATHER LARGE
GALE FORCE LOW WITH ITS FRONT DRIVING NORTHWARD FROM THE NORTH
PACIFIC TOWARDS THE EASTERN HALF OF THE ALEUTIAN CHAIN. GALE
FORCE WINDS WITH UP TO STORM FORCE WIND GUSTS OVERSPREAD THE CHAIN
TONIGHT. A COUPLE AREAS OF INTEREST WILL BE COLD BAY AND DUTCH
HARBOR. COLD BAY'S FAVORABLE SOUTHEASTERLY WIND DIRECTION
FUNNELING THROUGH THE TERRAIN THERE WILL LEAD TO STRONG, GUSTY
WINDS. MEANWHILE, DUTCH HARBOR IS ESPECIALLY VULNERABLE TO A
SOUTHEASTERLY TO EASTERLY WIND DIRECTION, AND THE PEAK DURATION OF
WINDS WILL LIKELY BE FRIDAY EVENING THROUGH SATURDAY MORNING.
UPPER LEVEL FEATURES DISAGREE ON PLACEMENT AND TIMING, BUT THE
BOTTOM LINE IS BY SATURDAY AFTERNOON, FRONTAL PRECIPITATION DRIVES
INTO THE BRISTOL BAY REGION AND COASTAL AREAS OF SOUTHWEST
ALASKA. THE AIRMASS CURRENTLY ACROSS SOUTHWEST ALASKA IS NOT
TERRIBLY COLD, BUT SHOULD BE COLD ENOUGH AT THE SURFACE AND ALOFT
TO SUPPORT A QUICK ROUND OF SNOW OR RAIN/SNOW MIX FOR THESE
LOCATIONS BEFORE CHANGING OVER TO A PERIOD OF FREEZING RAIN. THE
GFS AND EC SEEM TO BE THE COLDER SOLUTIONS MODEL WISE, WHILE THE
NAM IS THE WARMEST MODEL. FORECASTER CONFIDENCE LEANS MORE NAM
THAN THE GFS AND EC FOR A COUPLE OF REASONS. FIRST, SOUTHEAST
WINDS AT THE SURFACE, 925 MB, AND 850 MB WILL BRING IN A PUSH OF
RELATIVELY WARMER AIR FOR COASTAL SOUTHWEST ALASKA. SECONDLY,
FREEZING RAIN IS A SELF LIMITING P-TYPE, MEANING LATENT HEAT OF
FREEZING WILL ACTUALLY CAUSE THE AIRMASS AT THE SURFACE TO
MODERATE WITH NO DIRECT SUPPLY OF REINFORCING COLDER AIR TO OFFSET
THE WARMING. SO, THE IDEA FOR BRISTOL BAY AREAS WILL BE A FAIRLY
FAST SNOW TO FREEZING RAIN TO RAIN TRANSITION.
IT WILL TAKE A BIT LONGER FOR PRECIPITATION TO MOVE FARTHER
NORTHWARD ACROSS THE YUKON-KUSKOKWIM DELTA, WITH MOST OF THE
GUIDANCE INDICATING SNOW COULD FALL SUNDAY MORNING. FOR THESE
AREAS UNDER THE WINTER STORM WATCH, WARM AIR INTRUSION WILL MAKE
ITS APPEARANCE ALSO, THOUGH WITH TEMPERATURES WELL BELOW FREEZING
AND SURFACE WINDS SHIFTING MORE NORTHERLY, A CHANGEOVER TO
FREEZING RAIN WILL LIKELY BE A LONG DURATION EVENT. FOR THESE
LOCATIONS, WE WILL SEE A PERIOD OF SNOW TRANSITIONING TO FREEZING
RAIN AS A BAND SETS UP SHOP FOR THE YUKON-KUSKOKWIM DELTA REGION
AND POINTS FARTHER INLAND ACROSS THE VALLEY. BECAUSE COLD AIR IS
DENSE AND WANTS TO SINK, THIS MAKES IT TOUGH TO ERODE, SO VALLEY
LOCATIONS HAVE INCREASED FREEZING RAIN POTENTIAL AND COULD SEE
MORE ICE ACCUMULATION THAN NEARBY AREAS.
SUNDAY MORNING, THE GALE FORCE LOW DEVOLVES INTO A STRONG COMPLEX
LOW PRESSURE SYSTEM, AND THE GUIDANCE SUGGESTS THAT AN AREA OF
LOW PRESSURE COULD FORM ON ITS EASTERN PERIPHERY ACROSS THE
WESTERN GULF. IF THIS IS THE CASE, THE LOW WILL RETROGRADE
NORTHWESTWARD AND MOVE ACROSS SOUTHWEST ALASKA AND SEND A SECOND
WAVE OF MOISTURE ACROSS THE REGION, ADDING TO WHAT SNOW AND ICE
HAS ALREADY FALLEN. THE MOST UNCERTAIN PART OF THE FORECAST IS IF
THIS IN FACT MATERIALIZES, AND IF IT DOES, HOW MUCH MORE WARM
INTRUSION WILL TAKE PLACE AS SURFACE WINDS NORTHWEST OF THE LOW
SHIFT TO OUT OF THE NORTHEAST. PATTERN RECOGNITION POINTS TO THIS
RE-ESTABILISHING THE WARM NOSE EFFECT, WHICH WOULD LEAD TO ANOTHER
ROUND OF FREEZING RAIN AND JUST PLAIN RAIN FOR SOME AREAS THAT
ARE A BIT WARMER.
PRECIPITATION WILL LINGER WELL INTO LATE MONDAY AND TUESDAY, AS
THIS SYSTEM WILL LIKELY BE A LONG DURATION FREEZING RAIN/SNOW
EVENT FOR THE YUKON-KUKSOKWIM DELTA AND KUSKOKWIM VALLEY.
-AM
.LONG TERM FORECAST (DAYS 4 THROUGH 7 - TUESDAY THROUGH
FRIDAY)...
UNCERTAINTY CONTINUES TO BE AN ISSUE IN THE LONG TERM. A NORTH
PACIFIC LOW IS PROJECTED TO TRACK INTO THE BERING SEA WITH THE
LEADING FRONT BRINGING WIDESPREAD PRECIPITATION AND GALE FORCE TO
STORM FORCE WINDS FROM THE NORTHEAST DIRECTION ACROSS MUCH OF THE
BERING SEA. WINDS ALONG THE WESTERN PERIPHERY OF THE LOW WILL
BECOME NORTHERLY AS IT CROSSES THE WESTERN ALEUTIANS.
PRECIPITATION TYPE IS THE MAIN CHALLENGE FOR THE MAINLAND FOR THE
EARLY PART OF NEXT WEEK AS COOL TEMPERATURES REMAIN AT THE SURFACE
AND WARMER AIR FILTERS ACROSS THE REGION ALOFT. ALTHOUGH THE LOW
WEAKENS IN THE SOUTHERN BERING, IT IS NOT ENTIRELY CLEAR HOW LONG
THIS FORECAST CHALLENGE WILL PERSIST THROUGH THE REST OF THE WEEK.
THIS SYSTEM APPEARS TO BRING A PROLONGED PATTERN, ESPECIALLY FOR
SOUTHWEST ALASKA WITH STRONG WINDS, PRECIPITATION, AND WARM
SOUTHERLY AIR MOVING OVER COOL NORTHERLY AIR. FOR THE GULF AND
SOUTHCENTRAL, WAVES OF SURFACE LOWS AND FRONTS WILL TRANSIT THE
GULF, BUT SOME UNCERTAINTY REMAINS TO ITS STRENGTH AND TRAJECTORY
INTO THE NORTHERN GULF OR EASTERN GULF. AT THE LEAST, EXPECT
SHOWERS TO CONTINUE FOR COASTAL AREAS WITH LESS CLARITY FOR THE
LONG TERM WEATHER CONDITIONS FARTHER INLAND. TOWARD THE LAST HALF
OF THE WEEK THOUGH, A STRONG FRONT MOVES INTO THE WESTERN BERING
SEA FROM A KAMCHATKA LOW. STORM FORCE GUSTS SEEM MORE LIKELY ALONG
THE FRONT BUT MAY BE STUNTED PROGRESS AS IT BUMPS INTO A NARROW
AREA OF HIGH PRESSURE IN THE CENTRAL ALEUTIANS AND BERING SEA. AN
UPPER LEVEL BLOCKING PATTERN SEEMS POSSIBLE WITH HIGH PRESSURE TO
THE NORTH AND AREAS OF LOW PRESSURE WITH EMBEDDED DISTURBANCES
TRANSITING SOUTH AND ALONG THE ALEUTIANS. BREEZY GAP WINDS ACROSS
SOUTHCENTRAL WILL BE POSSIBLE FOR THE LATTER HALF OF THE WEEK.
AVIATION
PANC...VFR CONDITIONS WITH CEILINGS ABOVE 5000 FT AND LIGHT
NORTHERLY WINDS WILL PERSIST THROUGH THIS EVENING. VICINITY MIXED
PRECIPITATION SHOWERS ARE ALSO POSSIBLE THIS AFTERNOON/EARLY
EVENING, ALTHOUGH THE BULK OF ANY SHOWER ACTIVITY SHOULD REMAIN
EAST OF THE TERMINAL. FOG AND/OR LOW STRATUS MAY ALSO DEVELOP
TONIGHT AS WINDS AT AND NEAR THE SURFACE SLACKEN WHILE LOW-LEVEL
MOISTURE LINGERS UNDERNEATH A TRANSIENT RIDGE MOVING OVER THE
REGION. THIS INTRODUCES POTENTIAL FOR IFR VISIBILITY THROUGH
SATURDAY MORNING. LATER ON SATURDAY, ANY FOG WOULD BE SCOURED OUT
BY INCREASING NORTHERLY WINDS. PRECIPITATION CHANCES THEN INCREASE
BY SATURDAY AFTERNOON WITH THE ARRIVAL OF ANOTHER FRONTAL SYSTEM.
ANY STEADY PRECIPITATION WOULD LIKELY FALL AS FREEZING RAIN, WITH
A GLAZE OF ICE ACCUMULATION POSSIBLE.
-TM/QUESADA
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