110
FXAK68 PAFC 041331
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
531 AM AKDT THU SEP 4 2025
SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3)
AN UPPER RIDGE PERSISTS ACROSS THE EASTERN PORTIONS OF
SOUTHCENTRAL AND ACROSS THE ALCAN BORDER. TOWARD THE YUKON-
KUSKOKWIM DELTA, IS A TROUGH AND SOUTHWEST FLOW PREVAILS FROM
SOUTHWEST ALASKA AND ACROSS COOK INLET INTO THE SUSITNA VALLEY.
PRECIPITATION FOR SOUTHCENTRAL THIS MORNING IS CONFINED TO THE FAR
NORTHERN SUSITNA VALLEY AREA AND WESTERN COOK INLET, ALONG THE
WESTERN ALASKA RANGE. FOG HAS BEEN ISOLATED AND PATCHY WHERE SKIES
WERE ABLE TO CLEAR. AREAS OF FOG WAS ALSO OBSERVED ACROSS THE
COASTAL MARINE ZONES IN THE NORTH AND NORTHEASTERN GULF.
THE TROUGH OUT WEST IS EXPECTED TO PUSH EASTWARD TODAY AND SHOULD
BRING A ROUND OF RAINFALL ACROSS THE REGION BEFORE CONTINUING
TOWARDS THE COPPER BASIN FRIDAY. STEADIER RAIN WITH OROGRAPHIC
LIFT ALONG THE TALKEETNA MOUNTAINS, CHUGACH RANGE, AND NORTHERN
KENAI MOUNTAINS IS EXPECTED LATER THIS EVENING THROUGH FRIDAY
MORNING. ANYWHERE FROM AROUND TWO-TENTHS TO ABOUT HALF INCH OF
RAIN IS POSSIBLE FOR THESE AREAS, INCLUDING ANCHORAGE. HIGH
PRESSURE REMAINING OVER THE GULF AND THE COPPER BASIN AHEAD OF THE
APPROACHING TROUGH WILL HELP TO STRENGTHEN THE PRESSURE GRADIENT
OVER THE COASTAL MOUNTAINS RESULTING IN GUSTY SOUTHERLY WINDS THIS
AFTERNOON FOR THE COPPER RIVER VALLEY PRIOR TO THE FRONTAL
PASSAGE. THERMAL RIDGING BUILDING INTO THE COPPER BASIN WILL
LIKELY ALLOW FOR TEMPERATURES TO CLIMB BACK INTO THE MID 70S
TODAY.
FOLLOWING THE DEPARTURE OF THE FRONT, BRIEF RIDGING OVER
SOUTHCENTRAL ALASKA WILL ALLOW FOR DRIER CONDITIONS FOR FRIDAY,
BUT WILL BE ACCOMPANIED BY COOLER TEMPERATURES. THE POTENTIAL FOR
RAIN RETURNS AGAIN FOR SATURDAY AS THE ACTIVE PATTERN AND PARADE
OF LOWS IN THE BERING CONTINUES.
.SHORT TERM FORECAST SOUTHWEST ALASKA / BERING SEA / ALEUTIANS
(WEDNESDAY TO SATURDAY)...
NORTHWESTERLY ONSHORE WINDS INTO SOUTHWEST ALASKA EARLY THIS
MORNING WILL DIMINISH INTO THE AFTERNOON AS THE REMNANTS OF A LOW
PRESSURE SYSTEM EXIT THE REGION, REPLACED BY A WEAK TRANSIENT
RIDGE OVER THE CENTRAL BERING. SHOWERS DRIVEN BY THE EXITING LOW
OVER SOUTHWEST WILL CONTINUE THIS MORNING, HOWEVER DIMINISH
THROUGH THE DAY, PERSISTING INTO THE EVENING OVER THE KUSKOKWIM
DELTA AND THE LOWER KUSKOKWIM VALLEY. THE RIDGE SETS UP IN THE
BERING ON THURSDAY AND ALLOWS FOR CALMER WINDS AND LOWER CHANCES
FOR RAIN IN THE EASTERN ALEUTIANS AND PRIBILOF ISLANDS, WITH
PATCHES OF FOG EXPECTED IN THE MORNINGS AND EVENINGS.
OUT WEST, A NEW LARGE LOW PRESSURE SYSTEM IS ENTERING THE WESTERN
ALEUTIANS, BRINGING STRONGER WINDS AND MODERATE TO HEAVY RAINFALL
RATES. THE LOW CENTER WILL TRACK NORTHEASTWARD, ENTERING THE
BERING BY THIS AFTERNOON, AND CONTINUING TO PUSH IT'S FRONT
STEADILY EASTWARD ACROSS THE ALEUTIAN CHAIN. THE FRONT, REACHING
ADAK ISLAND EARLY THIS MORNING, IS EXPECTED TO REACH THE PRIBILOF
ISLANDS AND NIKOLSKI BY TONIGHT. WIND SPEEDS ON THE NORTHERN SIDE
OF THE LOW IN THE CENTRAL BERING ARE EXPECTED TO APPROACH STORM-
FORCE OUT OF THE EAST, WITH NEAR STORM-FORCE NORTHERLY WINDS ALSO
EXPECTED ALONG THE WESTERN SIDE OF THE LOW. FOLLOWING THE LOW'S
AND FRONT'S PROGRESSION, GUSTY SOUTHERLY ONSHORE WIND IS EXPECTED
TO ESTABLISH FOR COASTAL REGIONS OF SOUTHWEST ALASKA. WINDS WILL
GROW AND REACH GALE-FORCE ONSHORE, MAINLY FROM LATE FRIDAY NIGHT
INTO SATURDAY MORNING. GIVEN THE STRONG ONSET OF FAVORABLE WIND
FLOW, COASTAL EROSION AND HIGH SURF ALONG THE KUSKOKWIM DELTA AND
NORTHERN BRISTOL BAY IS POSSIBLE, HOWEVER WE WILL CONTINUE TO
MONITOR THE PROGRESSION OF THIS SYSTEM. WITH THE LOW ARRIVING IN
SOUTHWEST ALASKA BY LATE FRIDAY, WIDESPREAD RAINFALL ACROSS THE
MAINLAND WILL RESUME, CONTINUING INTO THE WEEKEND.
-CL
.LONG TERM FORECAST (DAYS 4 THROUGH 7 - SUNDAY THROUGH
WEDNESDAY)...
A SERIES OF GALE TO STORM-FORCE LOWS TRAVERSE THE BERING SEA
TOWARD MAINLAND ALASKA THIS WEEKEND THROUGH MID-NEXT WEEK. AT THE
BEGINNING OF THE LONG TERM FORECAST ON SUNDAY, THERE IS GOOD
MODEL AGREEMENT ON THE PLACEMENT OF A BROAD, WEAKENING LOW
TRACKING INLAND OVER THE YUKON-KUSKOKWIM DELTA, WITH NORTHWESTERLY
WINDS UP TO GALE FORCE ON THE BACK SIDE OF THE LOW, STREAMING DOWN
ACROSS THE CENTRAL/EASTERN BERING SEA AND ACROSS THE ALASKA
PENINSULA. ASSOCIATED WITH THE LOW, AN AREA OF RAIN SHOWERS
EXTENDS ACROSS SOUTHWEST ALASKA INTO WESTERN PORTIONS OF
SOUTHCENTRAL. THE COPPER RIVER BASIN WILL SEE A CHANCE OF SHOWERS,
BUT IS THE PORTION OF THE MAINLAND WITH THE BEST CHANCE OF
REMAINING DRY THIS WEEKEND.
A RIDGE OVER THE WESTERN/CENTRAL ALEUTIANS KEEPING THE AREA CALMER
AND DRIER QUICKLY SHIFTS EAST AS A STRONGER LOW PRESSURE SYSTEM
IN THE NORTH PACIFIC APPROACHES THE ISLANDS. THERE IS LESS
CONFIDENCE IN THE TRACK AND INTENSITY OF THIS LOW, BUT THERE IS
POTENTIAL FOR THIS LOW TO BRING STORM FORCE WINDS TO PORTIONS OF
THE SOUTHERN AND WESTERN BERING SEA, ALONG WITH THE WESTERN AND
CENTRAL ALEUTIANS LATE SUNDAY INTO MONDAY. THE LOW HAS ORIGINS IN
THE TROPICAL WEST PACIFIC, LIKELY THE EXTRATROPICAL REMNANTS OF A
TROPICAL DEPRESSION CURRENTLY SOUTHWEST OF JAPAN. THIS MEANS
ABUNDANT MOISTURE, WITH PRECIPITABLE WATER VALUES IN EXCESS OF 1.5
INCHES LIKELY LEADS TO MODERATE TO HEAVY RAIN ALONG THE ALEUTIAN
CHAIN AND PORTIONS OF THE ALASKA PENINSULA THROUGH EARLY TUESDAY.
MEANWHILE, SHOWERS LINGER OVER SOUTHCENTRAL ALASKA, SPREADING
POTENTIALLY INTO THE COPPER BASIN ON MONDAY WITH THE UPPER-LEVEL
REMNANT TROUGHING FROM THE SURFACE LOW OPENING INTO A SURFACE
TROUGH OVER WESTERN ALASKA.
HEADING INTO MID-WEEK, THE SECOND BERING SEA LOW SPREADS AMPLE
MOISTURE INTO SOUTHERN MAINLAND ALASKA. CHANCES INCREASE FOR LIGHT
TO MODERATE RAINFALL TUESDAY AND WEDNESDAY. ADDITIONALLY, WITH
THE STRONGER WINDS AND TIDES IN SOME AREAS OF SOUTHWEST ALASKA
REACHING THE HEIGHT OF THEIR CYCLE, THERE IS LOW, BUT NON-ZERO
CONCERN FOR COASTAL FLOODING/EROSION IMPACTS.
QUESADA
AVIATION
PANC...VFR CONDITIONS WILL GENERALLY PREVAIL THROUGH MOST OF THE
MORNING. TURNAGAIN ARM WINDS HAVE COME INTO THE TERMINAL EARLY
THIS MORNING, AND GUSTS TO AROUND 20 KTS OR SO WILL LIKELY PERSIST
FOR THE NEXT FEW HOURS. WINDS WILL BECOME LIGHTER AND MORE
SOUTH/SOUTHWESTERLY BY THIS AFTERNOON. A FRONTAL SYSTEM MOVING IN
WILL ALSO PUSH A BAND OF RAIN IN FROM THE WEST STARTING AROUND 3Z
TO 6Z THIS EVENING. CEILINGS WILL LOWER NEAR THE ONSET OF
RAINFALL, AND ITS LOOKING INCREASINGLY LIKELY FOR THEM TO DROP
INTO MVFR RANGE FROM THIS EVENING THROUGH THE END OF THE TAF
PERIOD.
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