046
FXAK68 PAFC 271348
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
548 AM AKDT THU AUG 27 2026
SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3)
KEY MESSAGES:
- MOSTLY CLEAR SKIES THROUGH THIS AFTERNOON/EVENING, THEN RAIN AND
WINDS RETURN AS A LOW PRESSURE SYSTEM MOVES ACROSS SOUTHCENTRAL
THROUGH SATURDAY AFTERNOON.
- FOR SUSITNA VALLEY, 48-HOUR RAIN TOTALS AROUND 0.5 TO 1.5 INCHES
WILL ALLOW FOR RISES ON MANY SMALL STREAMS AND RIVERS, AND LOCALIZED
PONDING IN LOW-LYING OR POOR DRAINAGE AREAS.
- WINDS PICK THROUGH COOK INLET AND ALONG PRINCE WILLIAM SOUND BY
LATE THURSDAY, WITH LOCALIZED GUSTY SOUTHEASTERLY GAP WINDS THROUGH
ANCHORAGE AND COPPER RIVER VALLEY.
DISCUSSION:
A SHORTWAVE TROUGH THAT BROUGHT RAIN SHOWERS OVERNIGHT TO THE COPPER
BASIN IS EXITING TO THE EAST THIS MORNING WITH CLEARING OF CLOUDS
ALLOWING FOR POCKETS OF FOG TO DEVELOP ALONG THE RIVER VALLEYS. FOG
AND LOW STRATUS WILL BEGIN TO MIX OUT BY MID-MORNING WITH GENERALLY
CLEAR SKIES AND WARM TEMPERATURES THIS AFTERNOON. THE REST OF
SOUTHCENTRAL HAS REMAINED MOSTLY CLEAR OVERNIGHT, BUT ANY HINT OF
FOG DEVELOPING IN THE KNOWN TROUBLE SPOTS HAS BEEN LACKING AS OF 4AM
THIS MORNING, WITH THE EXCEPTION OF CORDOVA WHERE PATCHY FOG HAS
DEVELOPED. ANY FOG THAT DOES DEVELOP IN THESE OTHER LOCATIONS WILL
ALSO MIX OUT BY MID TO LATE MORNING.
NEAR NORMAL TEMPERATURES TODAY AND MOSTLY CLEAR SKIES WILL MAKE FOR
A BEAUTIFUL MORNING AND EARLY AFTERNOON. CLOUD COVER WILL BEGIN TO
INCREASE FROM WEST TO EAST AS THE NEXT ADVERTISED SYSTEM STARTS TO
APPROACH SOUTHCENTRAL. THIS SYSTEM, WHICH IS CURRENTLY WAY OUT IN
THE BERING SEA NEAR KAMCHATKA, WILL PUSH A WARM FRONT ACROSS
SOUTHWEST THIS MORNING THEN INTO SOUTHCENTRAL BY THIS AFTERNOON. THE
COLD FRONT LOOKS TO QUICKLY OVERTAKE THE WARM FRONT BY LATE
AFTERNOON INTO THIS EVENING. WIDESPREAD RAIN WILL SPREAD INTO
SOUTHCENTRAL TONIGHT...FIRST INTO THE WESTERN SUSITNA VALLEY, BUT
QUICKLY PUSHING INTO THE COOK INLET, MAT-SU, KODIAK, AND KENAI
PENINSULA. THE HEAVIEST RAINFALL LOOKS TO FALL TONIGHT BEFORE
TAPERING OFF TO MORE SHOWERY FRIDAY MORNING. A SECONDARY TROUGH AND
ASSOCIATED FRONT WILL REINVIGORATE MORE ROBUST RAIN SHOWERS FRIDAY
AFTERNOON. THIS SYSTEM, LIKE THE PREVIOUS SYSTEM, IS FAIRLY
PROGRESSIVE AND WILL QUICKLY MOVE THROUGH...HELPING TO MINIMIZE SOME
OF THE FLOOD CONCERNS. HOWEVER, WITH RIVER LEVELS STILL HIGH FROM
OUR RAIN EARLIER THIS WEEK, PARTS OF SUSITNA VALLEY WILL LIKELY SEE
MINOR IMPACTS AS THE WATERSHED ABSORBS THIS ADDITIONAL RAINFALL.
THIS SYSTEM WILL ALSO BRING ANOTHER ROUND OF GUSTY GAP FLOW WINDS
FOR THE TURNAGAIN ARM, KNIK, AND COPPER VALLEY. SIMILAR TO THE
TUESDAY, WINDS WITH GUSTS UP TO 45 MPH ARE POSSIBLE FOR WEST
ANCHORAGE AND THE HILLSIDE. THE WESTERN GULF WILL SEE SMALL CRAFT TO
GALES MOVE IN BEHIND THE FRONT AND THE DEVELOPMENT OF A BARRIER JET
WILL ALLOW FOR SOME GALES ALONG THE NORTHERN GULF COAST. THESE
STRONG WINDS WILL LIKELY PUSH INLAND SOME BRINGING GUSTY WINDS TO
CORDOVA FRIDAY NIGHT.
- PP
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS
(DAYS 1 THROUGH 3: THIS AFTERNOON THROUGH SATURDAY EVENING)...
KEY MESSAGES:
* A WIND ADVISORY REMAINS IN EFFECT FOR THE KUSKOKWIM DELTA,
WESTERN CAPES, AND NORTHERN BRISTOL BAY COAST FROM 10AM THURSDAY
TO 4PM FRIDAY. SOUTH TO SOUTHWEST WINDS 25 TO 35 MPH WITH GUSTS
UP TO 50 MPH ARE EXPECTED.
* MODERATE TO HEAVY RAIN ACROSS SOUTHWEST ALASKA THIS AFTERNOON
THROUGH TONIGHT, AND TAPERS TO SHOWERS THROUGH FRIDAY.
* DRYING TREND ACROSS SOUTHWEST ALASKA AND THE ALASKA PENINSULA
SATURDAY.
* ANOTHER SYSTEM MOVES INTO THE BERING SATURDAY.
DISCUSSION:
AS OF THIS MORNING, SATELLITE IMAGERY AND CURRENT OBSERVATIONS
SHOW A BROAD, OCCLUDED LOW PRESSURE SYSTEM WITH THE PARENT LOW
SITTING WELL TO THE NORTH OF THE WESTERN ALEUTIANS. ITS ATTENDANT
FRONT IS IN THE PROCESS OF OCCLUDING, WITH A TRIPLE POINT LOCATED
BETWEEN THE PRIBILOF ISLANDS AND SAINT MATTHEW ISLAND. ALOFT, A
ROBUST DIGGING TROUGH ANCHORED BY THE SYSTEM'S UPPER LEVEL LOW
COMPONENT IS YIELDING SYNOPTIC SCALE LIFT DOWNSTREAM CLOSER TO THE
PRIBILOF ISLANDS. AIDED BY A SURFACE NORTH PACIFIC HIGH, THE
PRESSURE GRADIENT FROM REINFORCED SOUTHERLY FLOW BETWEEN THE
SURFACE LOW AND HIGH HAS YIELDED A SWATH OF GALES IN THE WAKE OF
THE SYSTEM'S LEADING WARM FRONT CURRENTLY SITUATED WEST OF THE
PRIBILOF ISLANDS. AHEAD OF THE WARM FRONT, THERE ARE AREAS OF LOW
STRATUS, MIST, AND PATCHY FOG. ALONG SIDE THE WINDS, A RICH SUPPLY
OF MOISTURE FROM THE SUBTROPICAL AND TROPICAL PACIFIC IS BEING
DIRECTED NORTHWARD IN PART DUE TO THE ANTI-CYCLONIC SURFACE FLOW
AROUND THE NORTH PACIFIC RIDGE. CURRENTLY, THIS AXIS OF MODERATE
RAINFALL IS LOCATED FROM THE RAT ISLANDS TO THE PRIBILOF ISLANDS
AND PUSHING ONSHORE ALONG THE SOUTHWEST COASTLINE.
SOUTHERLY TO SOUTHEAST WINDS ALONG THE SOUTHWEST ALASKA COAST
THIS MORNING WILL TURN SOUTHWESTERLY BY THIS AFTERNOON. EXPECT
GALE FORCE WINDS ALONG THE KUSKOKWIM DELTA COAST THIS AFTERNOON
INTO THIS EVENING. SOUTHWEST GUSTS INTO BETHEL WILL ALSO BE STRONG
AT TIMES THIS AFTERNOON AND EVENING. THE CORRIDOR OF GALE FORCE
WINDS MOVES SOUTHWARD INTO BRISTOL BAY AS WELL BY THIS EVENING.
WITH THIS, A WIND ADVISORY REMAINS IN EFFECT FOR THE KUSKOKWIM
DELTA COAST, INTERIOR KUSKOKWIM DELTA, THE WESTERN CAPES, AND THE
NORTHERN BRISTOL BAY COAST FROM 10 AM AKDT THIS MORNING THROUGH 4
PM AKDT FRIDAY TO ADDRESS THE GUSTY SOUTHERLY TO SOUTHWESTERLY
WINDS. ADDITIONALLY, DUE TO THE TROPICAL NATURE OF THE AIRMASS
ACCOMPANYING THIS SYSTEM AND STRONG JET DYNAMICS, A FEW LIGHTNING
STRIKES HAVE BEEN NOTED OVERNIGHT AND THIS MORNING ALONG THE
ALEUTIAN CHAIN MARINE ZONES, AND THERE IS MEDIUM TO HIGH
CONFIDENCE IN A FEW MORE ISOLATED STRIKES OVER THE BRISTOL BAY
WATERS BY THIS EVENING AS THIS SYSTEM PROGRESSES EASTWARD.
THE FETCH OF SOUTHWESTERLY WINDS INTO KUSKOKWIM BAY AND BRISTOL
BAY WILL BE QUITE LENGTHY. WAVE HEIGHTS IN KUSKOKWIM BAY WILL
BUILD THROUGH THURSDAY WITH PEAK HEIGHTS AROUND 5 TO 7 FT NEAR THE
COAST WITH 8 TO 11 FT AWAY FROM THE COAST. PEAK HEIGHTS SHOULD
OCCUR THURSDAY AFTERNOON THROUGH EVENING BEFORE SLOWLY SUBSIDING
THROUGH FRIDAY. WAVE HEIGHTS ACROSS BRISTOL BAY WILL BE SIMILAR
WITH PEAK WAVE HEIGHTS OCCURRING THURSDAY EVENING AND NIGHT BEFORE
SLOWLY SUBSIDING THROUGH FRIDAY.
ASIDE FROM THE WINDS AND ROUGH SEAS ALONG THE SOUTHWEST COAST,
THE OTHER MAIN THEME WITH THIS SYSTEM WILL BE HEAVY RAIN. AS
MENTIONED PREVIOUSLY, RAIN IS OVERSPREADING THE KUSKOKWIM DELTA
COAST THIS MORNING AND WILL FILL IN ACROSS THE REST OF SOUTHWEST
THROUGH THE REST OF THE DAY. RAIN PICKS UP IN INTENSITY THIS
AFTERNOON THROUGH TONIGHT AS A STRONG SHORTWAVE MOVES OVER THE
AREA AND 850 MB WINDS INCREASE. HEAVY RAIN TAPERS TO SHOWERS
ACROSS THE KUSKOKWIM DELTA BY THIS EVENING AS HEAVY RAIN PUSHES
EAST INTO THE KUSKOKWIM VALLEY, BRISTOL BAY, AND ALONG THE WESTERN
ALASKA RANGE THIS EVENING.
THE SURFACE LOW TRACKS INTO NORTON SOUND BY FRIDAY MORNING AS THE
MAIN UPPER-LEVEL TROUGH BEGINS TO MOVE INTO SOUTHWEST FROM THE
BERING. THIS WILL KEEP STEADY RAIN GOING ACROSS THE MOUNTAIN
RANGES AIDED BY SOUTHWESTERLY UPSLOPE FLOW. COLDER AIR MOVES INTO
SOUTHWEST FROM THE BERING AND CREATES MORE OF A SHOWERY REGIME
ACROSS THE REST OF THE AREA. SHOWERS WILL TAPER OFF FROM WEST TO
EAST THROUGH SATURDAY AFTERNOON AS THE AREA FINALLY BEGINS TO SEE
A DRYING TREND. WHEN ALL IS SAID AND DONE, ABOUT 0.50 TO 2.5
INCHES OF RAIN WILL FALL ACROSS SOUTHWEST FROM EARLY THURSDAY
MORNING THROUGH EARLY SATURDAY MORNING. THE HIGHEST TOTALS WILL BE
ALONG THE WESTERN ALASKA RANGE WITH THE HELP OF THE SOUTHWESTERLY
UPSLOPE FLOW. THE LOWER TOTALS LOOK TO FALL ACROSS INTERIOR
BRISTOL BAY WHEN FLOW TURNS WEST-SOUTHWEST THURSDAY EVENING AND
NIGHT WILL HELP DOWNSLOPE SOME OF THE HIGHER MOISTURE CONTENT.
ANOTHER PUSH OF WARM, MOIST, TROPICAL AIR MOVES INTO THE SOUTHERN
BERING FROM THE NORTH PACIFIC SATURDAY MORNING THROUGH SATURDAY
EVENING. ANOTHER UPPER LEVEL LOW WILL TRACK ACROSS KAMCHATKA
SATURDAY MORNING AND MOVE INTO THE EXTREME WESTERN BERING THROUGH
SATURDAY EVENING. BOTH THE UPPER LEVEL SYSTEM AND SURFACE LOW LOOK
TO BE WEAKER SATURDAY IN CONTRAST TO THE SYSTEM FOR
THURSDAY/FRIDAY. NONETHELESS, RAIN WILL MOVE INTO SHEMYA BY
SATURDAY MORNING AND ADVANCE NORTH AND EASTWARD ACROSS THE BERING
TO NEAR THE PRIBILOF ISLANDS BY SATURDAY EVENING. SUSTAINED WINDS
WITH THIS SYSTEM LOOK TO BE SMALL-CRAFT OR LESS AT THIS TIME. STAY
TUNED FOR FORECAST UPDATES AS THE STORMY PATTERN ACROSS THE
BERING CONTINUES TO UNFOLD.
-AM/DN
LONG TERM FORECAST (DAYS 4 THROUGH 7: SUNDAY THROUGH WEDNESDAY)
THE PROGRESSIVE PATTERN LOOKS TO CONTINUE INTO EARLY NEXT WEEK AS
MULTIPLE SYSTEMS MOVE THROUGH SOUTHERN ALASKA. THIS WILL
GENERALLY BRING PERIODS OF ACTIVE WEATHER, WITH SOME LULLS BETWEEN
SYSTEMS.
TROUGHING EXITS SOUTHCENTRAL EARLY SUNDAY MORNING WITH THE
SURFACE LOW MOVING INTO THE NORTHERN GULF. THIS WILL INCREASE
NORTHWESTERLY WINDS THROUGH THE BARREN ISLANDS AND AROUND KODIAK
ISLAND/THE AKPEN TO SMALL-CRAFT FORCE SUNDAY INTO MONDAY. A
SHORTWAVE RIDGE MOVES THROUGH SOUTHERN ALASKA ON SUNDAY. A FEW
SHORTWAVES MAY RIDE THE PERIPHERY OF THE RIDGE, WHICH MAY INDUCE
ISOLATED TO SCATTERED SHOWERS IN HIGHER ELEVATIONS OF SOUTHWEST
AND SOUTHCENTRAL, OTHERWISE SUNDAY LOOKS TO BE MOSTLY CALM INLAND.
BY SUNDAY EVENING, AN ARCTIC LOW DIVES SOUTH INTO THE WESTERN
INTERIOR. THIS LOW CONTINUES SOUTHEASTWARD THROUGH SOUTHCENTRAL
AND INTO THE ALASKA PANHANDLE BY WEDNESDAY. MODELS DIVERGE WITH
EXACT TIMING BUT AGREE ON FEATURES WITH THIS LOW. AS THE LOW MOVES
SOUTH, TEMPERATURES WILL COOL. THIS WILL ESPECIALLY BE THE CASE
FOR SOUTHWEST AS MANY LOCATIONS MAY STRUGGLE TO GET ABOVE THE MID
50S MONDAY-WEDNESDAY. LOWEST ELEVATIONS OF SOUTHCENTRAL WILL BE
SLIGHTLY WARMER, THOUGH LIKELY STRUGGLE TO REACH 60. SCATTERED
SHOWERS WILL CONTINUE TO ACROSS EASTERN PORTIONS OF SOUTHWEST AND
MUCH OF SOUTHCENTRAL AS THE UPPER LOW PASSES THROUGH. COOLER
TEMPERATURES WILL DROP SNOW LEVELS TO AROUND 4000-5000 FT. SOME
TERMINATION DUST (SNOWFALL) MAY BE SEEN ON THE HIGHEST PEAKS OF
THE CHUGACH FRONT RANGE AND KENAI MOUNTAINS, AS WELL AS SOME LOWER
PORTIONS OF THE ALASKA RANGE BY THE MIDDLE OF NEXT WEEK. A
SURFACE LOW LOOKS TO DEVELOP IN THE GULF MONDAY INTO TUESDAY AND
MAINTAIN SMALL- CRAFT NORTHWESTERLY WINDS AROUND KODIAK ISLAND,
THE AKPEN, AND THROUGH THE BARREN ISLANDS INTO THE GULF THROUGH
WEDNESDAY MORNING.
FOR THE SOUTHERN AKPEN, THE ALEUTIANS, AND THE BERING, MOST
MODELS AGREE WITH A FLAT RIDGE PERSISTING OVERHEAD THROUGH
TUESDAY, BUT DIVERGE ON SURFACE FEATURES BELOW. SOME PRECIPITATION
LOOKS LIKELY MONDAY- TUESDAY IN THE AKPEN AS NORTHWEST WINDS
UPSLOPE AGAINST THE MOUNTAINS. OTHER THAN THAT, THERE ARE MAJOR
DIFFERENCES BETWEEN MODELS REGARDING POTENTIAL SYSTEMS MOVING INTO
THE BERING. EVEN WITH THESE DIFFERENCES, AREAS OF RAIN AND SMALL-
CRAFT WINDS ARE POSSIBLE THROUGHOUT THE BERING AND ALEUTIANS
THROUGH WEDNESDAY. IF A SYSTEM IS ABLE TO TRACK THROUGH THE BERING
AND REACH THE COAST, SOUTHWEST MAY RECEIVE ADDITIONAL RAINFALL
TUESDAY INTO WEDNESDAY. DETAILS WILL BECOME MORE CLEAR IN THE
COMING DAYS.
- PA
AVIATION
PANC...VFR CONDITIONS AND LIGHT WINDS WILL PERSIST. WHILE PATCHY
FOG NEAR THE AIRPORT EARLY THIS MORNING CANNOT BE FULLY RULED
OUT, IT LOOKS UNLIKELY AT THIS TIME. RAIN WILL SPREAD INTO THE
TERMINAL TONIGHT WITH TURNAGAIN ARM WINDS INCREASING FRIDAY
MORNING WITH GUSTS UP TO 45 KT.
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