879
FXAK68 PAFC 211330
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
530 AM AKDT TUE JUL 21 2026
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH
3: TODAY THROUGH THURSDAY)...
THE GENERAL FORECAST PICTURE REMAINS ON TRACK, WITH WET AND WINDY
CONDITIONS CONTINUING THROUGH MUCH OF THE WORK WEEK AS A
SUCCESSION OF STORMS MOVES THROUGH SOUTHCENTRAL ALASKA. FLOOD
WATCHES ARE NOW IN EFFECT FOR SUSITNA VALLEY, HATCHER PASS, AND
WESTERN KENAI PENINSULA DUE TO EXCESSIVE RAINFALL BEGINNING TODAY
AND CONTINUING THROUGH MIDWEEK. IN ADDITION, FLOOD ADVISORIES
REMAIN IN EFFECT FOR THE YENTNA AND SKWENTNA RIVERS. THE OTHER
HAZARD WE'RE MONITORING IS THE POTENTIAL FOR GUSTY SOUTHEASTERLY
WINDS THROUGH ANCHORAGE, PALMER, AND COPPER RIVER VALLEY. FOR
ANCHORAGE IN PARTICULAR, THE COMBINATION OF GUSTY WINDS AND WET
SOILS FROM YESTERDAY'S RAIN COULD LEAD TO DOWNED TREES AND POWER
LINES.
DIVING INTO THE DETAILS... A VERY PROGRESSIVE, WET AND WINDY
PATTERN WILL CONTINUE THROUGH THURSDAY. WHILE MUCH OF THE
SOUTHCENTRAL MAINLAND IS CURRENTLY SEEING A TAPERING OFF OF RAIN
BEHIND YESTERDAY'S TROUGH, THE NEXT SHORTWAVE AND SURFACE LOW ARE
ALREADY MOVING INTO KODIAK ISLAND. RAIN WILL QUICKLY MAKE ITS WAY
NORTH TO KENAI PENINSULA SHORTLY, THEN TO THE REMAINDER OF
SOUTHCENTRAL BY THE LATTER HALF OF TODAY. THE PREVAILING FLOW
WITH THIS STORM SYSTEM WILL BE SOUTH TO SOUTHWEST AND WILL FAVOR
DIFFERENT AREAS FOR THE HEAVIEST PRECIPITATION THAN YESTERDAY'S
STORM SYSTEM. IT WILL ALSO MOVE THROUGH THE REGION MUCH MORE
QUICKLY. STILL, WITH ELEVATED WATER LEVELS IN AREA RIVERS AND
STREAMS AND A SATURATED GROUND, THERE WILL BE CONTINUED POTENTIAL
FOR MINOR FLOODING. AS MENTIONED ABOVE, THE OTHER THING TO WATCH
WILL BE INCREASING SOUTHEASTERLY WINDS AS A COASTAL RIDGE DEVELOPS
AHEAD OF THIS SYSTEM. HI-RES MODEL GUIDANCE IS HINTING AT GUSTS
APPROACHING 40-50 MPH FOR THE LOWER ELEVATIONS OF ANCHORAGE, AND
50-60 MPH FOR THE HILLSIDES.
RAIN WILL DIMINISH ACROSS THE REGION DURING THE DAY WEDNESDAY,
THEN MODERATE TO HEAVY RAIN WILL MOVE BACK IN WEDNESDAY NIGHT
BEFORE EXITING THURSDAY. THIS MID WEEK STORM LOOKS STRONGER IN ALL
WAYS, INCLUDING STRONGER WINDS AND HEAVIER RAINFALL. IN
PARTICULAR, THIS WILL FAVOR VERY HEAVY RAIN IN THE TALKEETNA
MOUNTAINS AND NEARBY PORTIONS OF THE MATANUSKA AND SUSITNA VALLEY.
AS A RESULT, FAST RESPONDING RIVERS AND STREAMS SUCH AS THE
LITTLE SUSITNA RIVER AND WILLOW CREEK WILL BE SUSCEPTIBLE TO
FLOODING. LARGER AND SLOWER RESPONDING RIVERS ACROSS THE SUSITNA
VALLEY WILL ALSO SEE FAIRLY HEAVY RAIN AND WON'T HAVE A CHANCE TO
DROP MUCH THIS WEEK, SO OUT OF BANK FLOODING IS ALSO LIKELY FOR
SOME OF THESE LOCATIONS.
COLD AIR ADVECTION (AND UNSTABLE AIR) WILL LEAD TO VERY WINDY
CONDITIONS WEDNESDAY NIGHT THROUGH THURSDAY. SOME OF THE STRONGEST
WINDS AND HIGHEST WAVES WILL IMPACT COOK INLET, KACHEMAK BAY, AND
THE KODIAK ISLAND WATERS WEDNESDAY NIGHT THROUGH THURSDAY, WITH
25 TO 35 KTS OF WIND LIKELY. KAMISHAK BAY TO THE BARREN ISLANDS
COULD SEE WINDS MORE REMINISCENT OF THE WINTER SEASON, WITH A
CHANCE OF WINDS REACHING AS HIGH AS 40 TO 45 KTS.
FOR THOSE LOOKING FOR A CHANCE FROM THIS WEATHER PATTERN, IT DOES
LOOK LIKE WARMER AND DRIER WEATHER IS ON THE WAY FOR FRIDAY AND
INTO THE WEEKEND.
-SEB/KC
.SHORT TERM FORECAST SOUTHWEST ALASKA AND THE BERING
SEA/ALEUTIANS (DAYS 1 THROUGH 3: TODAY THROUGH FRIDAY MORNING)...
A FAST-MOVING LOW, CURRENTLY JUST SOUTH OF NUNIVAK ISLAND THIS
MORNING, WILL MOVE ON SHORE OF THE NORTHERN KUSKOKWIM BAY COAST
THIS AFTERNOON. RAIN ACROSS THE KUSKOKWIM DELTA COAST, BRISTOL BAY
COAST, AND ALASKA PENINSULA (AKPEN) WILL CONTINUE TO SPREAD INLAND
THROUGH TODAY. THE AKPEN AND ALONG THE WESTERN ALASKA AND
NORTHERN ALEUTIAN RANGES WILL SEE THE MOST RAIN WITH TODAY'S
SYSTEM DUE TO DEEP AND MOIST SOUTH-SOUTHWESTERLY FLOW THROUGHOUT
THE ATMOSPHERE. RAINFALL AMOUNTS TODAY ACROSS BRISTOL BAY AND THE
AKPEN WILL RANGE FROM AROUND 1 TO 1.5 INCHES WITH THE HIGHEST
AMOUNTS ALONG THE MOUNTAIN RANGES. FOR THE KUSKOKWIM DELTA AND
KUSKOKWIM VALLEY, EXPECT 0.25 TO 0.50 INCHES OF RAINFALL WITH THE
HIGHEST AMOUNTS IN THE EASTERN KUSKOKWIM VALLEY. THE STRONG
DYNAMICS ASSOCIATED WITH THIS STORM HAVE HELPED TO SPARK OFF A FEW
MARINE THUNDERSTORMS ACROSS THE EXTREME SOUTHERN AKPEN, THROUGH
UNIMAK PASS, AND THE COASTAL MARINE ZONES SOUTH OF COLD BAY.
LIGHTNING ACTIVITY CURRENTLY NEAR SANAK ISLAND IS EXPECTED TO
MOVE EAST TO EAST-SOUTHEAST WITH TIME AND MAKE IT POTENTIALLY TO
NEAR THE SHUMAGIN ISLANDS LATER THIS MORNING. A MARINE WEATHER
STATEMENT HAS BEEN ISSUED FOR THE TWO COASTAL MARINE ZONES SOUTH
OF COLD BAY FOR FREQUENT LIGHTNING WITH THE STORMS NEAR SANAK
ISLAND. OTHERWISE, STEADY RAIN TAPERS TO SHOWERS THROUGH LATE
TONIGHT INTO EARLY WEDNESDAY MORNING STARTING WITH THE COAST THIS
AFTERNOON.
GUSTY SOUTHERLY TO SOUTHEAST WINDS WINDS ARE LIKELY ALONG THE
KUSKOKWIM DELTA COAST AND ALONG THE NORTHERN BRISTOL BAY COAST AS
WELL AS THE COASTAL WATERS ALONG THE COASTS THIS MORNING. WINDS
TURN SOUTHWESTERLY THROUGH THIS AFTERNOON AND EVENING ALONG THE
WATERS OF BRISTOL BAY AND MAINLAND BRISTOL BAY. WAVE HEIGHTS OF 4
TO 7 FEET IN THE COASTAL WATERS OF KUSKOKWIM BAY WILL SLOWLY
SUBSIDE THROUGH THE REST OF THE DAY. FOR BRISTOL BAY, WAVE HEIGHTS
OF 3 TO 6 FEET WILL BUILD TO 7 TO 10 FEET BY THIS AFTERNOON AND
EVENING AS THE FETCH COMES FROM THE SOUTHWEST. THESE WAVE HEIGHTS
WILL PERSIST INTO WEDNESDAY WITH LITTLE IN THE WAY OF SUBSIDING
AHEAD OF THE NEXT SYSTEM.
ATTENTION THEN TURNS TO THE NEXT BERING SYSTEM QUICKLY APPROACHING
ON THE HEELS OF TODAY'S. A LOW MOVES EAST OFF THE KAMCHATKA
PENINSULA AND INTO THE WESTERN BERING SEA BY THIS AFTERNOON. ITS
FRONT WILL SPREAD WARM AIR AND RAIN OVER THE WESTERN ALEUTIANS
TODAY. RAIN THEN MOVES EAST TO ADAK/ATKA AND THE PRIBILOF ISLANDS
BY LATE TONIGHT INTO EARLY WEDNESDAY MORNING. THE SYSTEM CONTINUES
TO DEEPEN AS IT MOVES JUST WEST OF SAINT MATTHEW ISLAND LATE
WEDNESDAY MORNING. BY THIS TIME, A SURGE OF WARM AIR AND MODERATE
TO HEAVY RAIN ASSOCIATED WITH THE FRONT WILL HAVE BEGUN TO MOVE
OVER COASTAL SOUTHWEST ALASKA. MODERATE TO HEAVY RAIN THEN MOVES
INLAND ACROSS THE REST OF SOUTHWEST THROUGH WEDNESDAY AFTERNOON
AND WEDNESDAY NIGHT. THE HEAVIEST RAIN WITH THIS SYSTEM WILL OCCUR
FARTHER NORTH THAN WITH TODAY'S SYSTEM. THE HEAVIEST RAIN IS
EXPECTED TO FALL ACROSS THE KUSKOKWIM DELTA, KUSKOKWIM VALLEY, AND
ALONG THE WESTERN ALASKA RANGE. EXPECT 1 TO 2 INCHES OF RAINFALL
FROM THIS SYSTEM FROM WEDNESDAY MORNING INTO THURSDAY MORNING FOR
THE KUSKOKWIM DELTA, KUSKOKWIM VALLEY, AND WESTERN ALASKA RANGE.
THE WESTERN ALASKA RANGE WILL SEE THE HIGHER-END TOTALS DUE TO
FAVORABLE UPSLOPE SOUTHWESTERLY FLOW. FOR BRISTOL BAY AND THE
AKPEN, EXPECT 0.50 TO 1 INCH OF RAINFALL WEDNESDAY MORNING INTO
THURSDAY MORNING. THE HIGHER-END TOTALS HERE WILL ALSO OCCUR
INLAND WITH THE FAVORABLE SOUTHWESTERLY UPSLOPE FLOW ALONG THE
WESTERN ALASKA RANGE AND NORTHERN ALEUTIAN RANGE.
LIKEWISE WITH TODAY'S SYSTEM, GUSTY WINDS, FROM THE SOUTH AND
SOUTHWEST, WILL MAKE IT OVER THE KUSKOKWIM DELTA AND NORTHERN
BRISTOL BAY COASTS BY WEDNESDAY MORNING. GALE-FORCE WINDS WILL
ALSO OCCUR OVER THE COASTAL WATERS OF THE KUSKOKWIM DELTA AND
NORTHERN BRISTOL BAY. EXPECT WAVE HEIGHTS TO BUILD ALONG THE
COASTAL WATERS OF KUSKOKWIM AND BRISTOL BAYS THROUGH WEDNESDAY
EVENING. PEAK WAVE HEIGHTS ALONG KUSKOKWIM BAY WILL BE 8 TO 11
FEET WITH 9 TO 13 FEET LIKELY FOR BRISTOL BAY. WAVE HEIGHTS WILL
SLOWLY SUBSIDE THROUGH THURSDAY MORNING. A SPECIAL WEATHER
STATEMENT HAS BEEN ISSUED FOR THE KUSKOKWIM DELTA COAST, THE
WESTERN CAPES, AND THE NORTHERN BRISTOL BAY COAST TO BRING FURTHER
AWARENESS TO THE HEAVY RAIN, GUSTY WINDS, AND ROUGH SEAS ALONG THE
COASTAL WATERS WITH EACH OF THE SYSTEMS SET TO IMPACT THE AREA.
AS MENTIONED ABOVE, SCATTERED RAIN SHOWERS WILL CONTINUE ACROSS
MAINLAND SOUTHWEST THROUGH THURSDAY AS THE AKPEN BEGINS TO DRY
OUT BY LATE THURSDAY MORNING INTO THURSDAY AFTERNOON. MEANWHILE,
ANOTHER ROUND OF RAIN AND WARM TROPICAL AIR MAKES ITS WAY TO THE
WESTERN ALEUTIANS WEDNESDAY EVENING THROUGH THURSDAY. THE NORTH
PACIFIC RIDGE BUILDS FARTHER NORTH OVER THE CENTRAL AND EASTERN
ALEUTIANS, SO ADAK/ATKA AND NIKOLSKI/UNALASKA/AKUTAN SHOULD REMAIN
MOSTLY DRY THURSDAY. SOME MOISTURE MAKES IT AROUND THE NORTHERN
PRECIPICE OF THE RIDGE AND ACROSS THE BERING TO THE PRIBILOFS AND
SOUTHERN AKPEN FOR FRIDAY MORNING. OTHERWISE, EXCEPT FOR SOME
LINGERING SHOWERS ALONG THE MOUNTAIN RANGES, SOUTHWEST LOOKS TO
FINALLY DRY OUT FOR FRIDAY. STAY TUNED FOR FORECAST UPDATES AS
THESE WET AND WINDY STORM BERING STORM SYSTEMS CONTINUE TO UNFOLD
ACROSS THE AREA.
LONG TERM FORECAST (DAYS 4 THROUGH 7: FRIDAY THROUGH MONDAY)
FRIDAY WILL BEGIN WITH HIGH PRESSURE OVER THE ALEUTIANS RIDGING
NORTHWARD INTO THE BERING. AT THE SAME TIME, A TROUGH OVER THE
INTERIOR OF ALASKA WILL BE PUSHING SOUTHWARD INTO THE NORTH
PACIFIC. RAIN CHANCES WILL PROMPTLY DIMINISH OVER ALASKA ON
SATURDAY WITH A TEMPORARY COL DEVELOPING SATURDAY MORNING. DRIER
CONDITIONS AND CALMER WINDS ARE LIKELY TO START THE WEEKEND. THE
FORECAST BECOMES A LITTLE MORE UNCLEAR ON SUNDAY WITH MODELS
SHOWING A PROGRESSIVE TROUGH DIGGING INTO THE STATE AND FOLLOWING
THE DOWNSTREAM SIDE OF THE RIDGE OF HIGH PRESSURE. THUS, RAIN
CHANCES WILL RETURN BRIEFLY ALONG WITH GUSTY NORTHERLY WINDS.
WHILE HIGH WINDS ARE NOT EXPECTED, GUSTY GAP WINDS WILL IMPACT
MOST OF THE MOUNTAIN PASSES FROM SOUTHWEST ALASKA TO SOUTHCENTRAL
ALASKA ALONG WITH BREEZIER CONDITIONS FOR THE LOWER ELEVATIONS.
BEHIND THE PROGRESSIVE TROUGH CONDITIONS WILL ONCE AGAIN CLEAR
ACROSS THE REGION ON MONDAY.
-BL
AVIATION
PANC...CEILINGS AND VISIBILITY WILL IMPROVE TO VFR THIS MORNING AS
RAIN TAPERS OFF, THOUGH CONFIDENCE IS LOWER REGARDING WHEN
CEILINGS MIGHT IMPROVE ABOVE 5000 FT. AS THE NEXT STORM APPROACHES
EARLY THIS AFTERNOON, SOUTHEASTERLY TURNAGAIN ARM WINDS AND RAIN
WILL REDEVELOP. THE HIGHEST RAIN RATES AND STRONGEST GUSTS (AROUND
30-40 KT) WILL LIKELY PEAK FROM ABOUT 02Z THROUGH 07Z THIS
AFTERNOON AND EVENING, WITH CEILINGS POTENTIALLY DIPPING INTO
MVFR. AFTER ABOUT 07Z, WINDS DIMINISH BUT REMAIN GUSTY. CONFIDENCE
IS LOWER REGARDING CEILING TRENDS, AS THIS WILL BE DEPENDENT ON
THE LOW TRACK.
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