847
FXAK68 PAFC 180715
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
1115 PM AKDT THU SEP 17 2026
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3:
TODAY THROUGH SATURDAY EVENING)...
KEY MESSAGES:
- WETTER CONDITIONS RETURN FROM FRIDAY INTO THE WEEKEND AS TWO
STORMS MOVE NORTH ACROSS THE GULF AND INTO SOUTHCENTRAL.
- TRENDING COLDER, WITH OVERNIGHT LOWS DIPPING INTO THE LOW 40S TO
LOW 30S BY FRIDAY NIGHT/SATURDAY MORNING.
DISCUSSION:
AS OF THIS AFTERNOON, TRANSIENT UPPER LEVEL RIDGING IS KEEPING
MUCH OF SOUTHCENTRAL RELATIVELY QUIET. MEANWHILE, UPSTREAM OF THIS
FEATURE IS A INCREASINGLY NEGATIVELY TILTED TROUGH OVER THE
EASTERN BERING AND SOUTHWEST ALASKA THAT IS PROGGED TO LIFT OVER
THE GULF AND TOWARDS THE SOUTHCENTRAL COAST WITH EMBEDDED
SHORTWAVE ENERGY THROUGH TONIGHT. AS SUCH, WITH A RETURN OF
SOUTHERLY TO SOUTHEASTERLY FLOW ALOFT, EXPECT AN INCREASE IN RAIN
SHOWER ACTIVITY ONCE AGAIN LATE THIS EVENING THROUGH FRIDAY
MORNING. THE FIRST OF THIS MOISTURE WILL ARRIVE FOR KODIAK ISLAND,
BUT THEN MORE SO FOR COASTAL PORTIONS OF SOUTHCENTRAL LATER IN
THE MORNING. WITH UPSLOPE ENHANCEMENT, EXPECT QPF VALUES TO BE
HIGHEST ALONG THE WINDWARD SLOPES OF THE EASTERN KENAI MOUNTAINS.
ON ANOTHER NOTE, THIS TROUGH WILL BE THE MAIN DRIVER OF DEEPENING
A COMPACT GULF LOW STARTING FRIDAY MORNING. MOST MODELS SEND THIS
LOW NORTH-NORTHEASTWARD TOWARDS CORDOVA AND THE COPPER RIVER DELTA
THROUGH FRIDAY AFTERNOON AND DEVELOP A NARROW, BUT STRONG HIGH-
END GALE BARRIER JET WITH STORM FORCE GUSTS OVER KAYAK ISLAND
BEFORE THE LOW EVENTUALLY MOVES INLAND EARLY SATURDAY MORNING.
LOOKING BACK TO THE WEST, SOME OF THIS PRECIPITATION FRIDAY
MORNING WILL LIKELY (60-70% CHANCE) SPILL OVER THE MOUNTAINS AND
INTO THE ANCHORAGE BOWL BEFORE SHOWER ACTIVITY DECREASES FOR
FRIDAY AFTERNOON AS THE TROUGH LIFTS NORTHWARD AND OUT OF THE
REGION.
MODELS THEN SHOW A ROBUST, DIGGING SHORTWAVE 500 MB TROUGH RIDING
SOUTH OF THE ALEUTIAN CHAIN AND BEGINNING TO TRANSLATE OVER THE
SOUTHERN GULF BY SATURDAY MORNING. THE PROGRESSION OF THIS FEATURE
WILL AID TO DEVELOP AND DEEPEN A LARGE SURFACE LOW PRESSURE
SYSTEM AS IT MOVES NORTHWARD ACROSS THE GULF SATURDAY MORNING.
MODELS DEEPEN THIS LOW IN THE 975 TO 985 MB RANGE, WHICH IS STRONG
ENOUGH FOR POTENTIAL GALES AS THE LOW LIFTS NORTHWARD. RAIN
AMOUNTS AND INTENSITY WILL ALSO BE SOMETHING TO WATCH, AS THE
NORTHERN GULF COAST (INCLUDING PRINCE WILLIAM SOUND AND EASTERN
KENAI PENINSULA) COULD SEE A LONG DURATION OF MODERATE RAIN.
LASTLY, WE ARE ARRIVING TO THE TIME OF YEAR WHERE SNOW LEVELS ARE
LOW ENOUGH IN THE MORNING FOR SOME AREAS TO WHERE WE CAN SEE SOME
HIGHER ELEVATION SNOWFALL. IN SAYING THAT, PLACES LIKE EUREKA LOOK
TO SEE SOME FLAKES FLY (40-60% CHANCE) SATURDAY MORNING, BUT VERY
LITTLE TO NO ACCUMULATION IS EXPECTED AT THIS TIME AND
TEMPERATURES ARE ON TRACK TO REBOUND INTO THE MID 40S FOR SATURDAY
AFTERNOON. NOW MAY BE THE TIME TO START THINKING ABOUT
WINTERIZING, ESPECIALLY AS TEMPERATURES BEGIN TO TREND COOLER
HEADING INTO NEXT WEEK.
-AM/TM
.SHORT TERM FORECAST SOUTHWEST ALASKA AND BERING SEA/ALEUTIANS
(DAYS 1 THROUGH 3)...
A BERING LOW WILL CONTINUE TO BRING CLOUDS WITH PERIODS OF RAIN
FOR SOUTHWEST AND THE AKPEN. A SHORTWAVE RIDGE OVER THE BERING
WILL CONTINUE TO BRING LOW STRATUS AND FOG OVER THE ALEUTIANS. AN
UPPER LEVEL JET STRENGTHENS AN EXISTING LOW TODAY OVER KAMCHATKA.
THE BERING LOW WILL TRACK INTO THE DELTA FRIDAY MORNING,
CONTINUING THE RAIN FOR SOUTHWEST AND THE AKPEN INTO SATURDAY. A
SHORTWAVE RIDGE TRACKS THROUGH THE BERING SEA, UNTIL DISSIPATING
OVER THE AKPEN FRIDAY MORNING. THE KAMCHATKA LOW ENTERS THE BERING
LATER THIS AFTERNOON AND PUSHES ITS INITIAL FRONT THROUGH SHEMYA.
THIS FRONT RACES THROUGH THE ALEUTIANS, REACHING UNALASKA
TOMORROW MORNING, WITH THE CENTER OF THE LOW NEAR ATKA. THE LOW
MOVES SOUTHWEST EXITING THE ALEUTIAN CHAIN, INTO THE NORTH PACIFIC
THROUGH FRIDAY AFTERNOON. NORTHERLY WINDS STRENGTHEN BEHIND THE
SYSTEM, FROM A RIDGE BUILDING OVER THE WESTERN BERING SEA. THESE
WINDS REACH THE PRIBILOF ISLANDS FRIDAY NIGHT, WITH HIGH
CONFIDENCE OF REACHING SMALL CRAFT CRITERIA.
THE FRONT EXITS THE PRIBILOF ISLANDS AND ALEUTIANS SATURDAY NIGHT
MOVING TO THE SOUTHEAST, UNTIL BECOMING STATIONARY SUNDAY MORNING
OVER BRISTOL BAY. THE FRONT WILL BRING NORTHWESTERLY WINDS THROUGH
THE COMMON GAPS AND PASSES IN THE ALASKA PENINSULA. A LOW FORMS
OFF THE FRONT IN THE BERING STRAIT AND MOVES THOUGH CAPE NEWENHAM
SUNDAY MORNING, GENERATING SHOWERS THROUGH SUNDAY EVENING, WITH
WINDS SHIFTING TO MORE NORTHWESTERLY.
-SS
LONG TERM FORECAST (DAYS 4 THROUGH 7: MONDAY THROUGH THURSDAY)
LONGWAVE TROUGH PATTERN DOMINATES SOUTHERN ALASKA EARLY NEXT WEEK.
THE MAIN LOW SITS IN THE GULF OF ALASKA THAT WILL MERGE WITH AN
A NORTH PACIFIC LOW AS IT MOVES TOWARDS THE SOUTHERN GULF OF
ALASKA ON TUESDAY. THERE IS RELATIVELY FAIR MODEL CONFIDENCE FOR
THIS LOW TRACKING INTO THE GULF, WEAKENING AND SHIFTING BACK SOUTH
THROUGH MID-WEEK NEXT WEEK. WIDESPREAD RAINFALL IS LIKELY ACROSS
SOUTHERN ALASKA, INCLUDING THE ALASKA PENINSULA AND ALEUTIAN
CHAIN, EARLY NEXT WEEK. AS THE INITIAL LOW FADES INTO THE NORTH
PACIFIC LOW AND THEN MOVES AWAY FROM THE SOUTHCENTRAL COAST,
PRECIPITATION WILL DIMINISH INLAND, LINGERING ALONG THE COAST
THROUGH WEDNESDAY MORNING.
MODEL CONFIDENCE IS STEADILY INCREASING FOR A LARGE LOW TO ENTER
THE BERING SEA MID TO LATE WEEK NEXT WEEK.
KM
AVIATION
PANC...LIGHT RAIN DEVELOPING OVER THE AREA WILL LIKELY LEAD TO
LOWER CEILINGS AND VISIBILITY TO MVFR LEVELS OVERNIGHT PERSISTING
THROUGH FRIDAY AFTERNOON. LIGHT SOUTHEASTERLY WINDS EARLY THIS
EVENING SHIFT TO NORTHERLY FOR FRIDAY AND REMAIN RELATIVELY LIGHT.
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