290
FXAK68 PAFC 210109
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
509 PM AKDT MON JUL 20 2026
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3/TONIGHT
THROUGH THURSDAY)...
A VERY PROGRESSIVE, WET AND WINDY PATTERN WILL CONTINUE THROUGH
THURSDAY. TAKING A LOOK AT SATELLITE IMAGERY THIS AFTERNOON, A
NEGATIVELY TILTED TROUGH IS LIFTING NORTHWARD ACROSS THE GULF
TOWARD SOUTHCENTRAL. AN ATMOSPHERIC RIVER WHICH HAS BEEN STREAMING
HIGH MOISTURE AIR HAS NOW LOST ITS TROPICAL PACIFIC CONNECTION.
EVEN SO, A NARROW BAND OF MODERATE RAIN AHEAD OF THE TROUGH
EXTENDS FROM PRINCE WILLIAM SOUND NORTHWESTWARD TO ANCHORAGE AND
THE MAT- SU. AREA RIVERS AND STREAMS ARE RUNNING HIGH ACROSS MUCH
OF THE REGION AND WE CONTINUE TO WATCH MULTIPLE AREAS FOR
POTENTIAL MINOR FLOODING, INCLUDING THE SUSITNA VALLEY, KENAI
PENINSULA, AND ANCHORAGE. SUNNY AND MUCH WARMER CONDITIONS ARE
BEING OBSERVED IN THE COPPER RIVER BASIN TODAY. ELEVATED
SOUTHEASTERLY WINDS CAN BE FOUND ALONG AND AHEAD OF THE
APPROACHING UPPER TROUGH AND SURFACE FRONT.
THE UPPER TROUGH AND SURFACE FRONT WILL RAPIDLY WEAKEN AS THEY
PROGRESS NORTH AND EAST TONIGHT, SO RAINFALL INTENSITY WILL
LIGHTEN UP AND THE COPPER BASIN WILL END UP WITH VERY LITTLE RAIN
OUT OF THIS. A FAST-MOVING UPPER LEVEL SHORT-WAVE AND SURFACE LOW
IN THE CENTRAL BERING SEA WILL TRACK TO SOUTHWEST ALASKA TUESDAY,
WITH RAIN KODIAK ISLAND UP TO THE KENAI PENINSULA TUESDAY MORNING,
THEN ACROSS THE REMAINDER OF SOUTHCENTRAL TUESDAY AFTERNOON
THROUGH TUESDAY NIGHT. THE PREVAILING FLOW WITH THIS NEXT STORM
SYSTEM WILL BE SOUTH TO SOUTHWEST AND WILL FAVOR DIFFERENT AREAS
FOR THE HEAVIEST PRECIPITATION THAN THE CURRENT 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.
FURTHERMORE, MODEL GUIDANCE IS TRENDING MUCH FASTER WITH THE NEXT
STORM CROSSING THE BERING SEA, LEAVING VERY LITTLE CHANCE FOR
WATER LEVELS TO DROP. 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
.SHORT TERM FORECAST SOUTHWEST ALASKA AND THE BERING
SEA/ALEUTIANS (DAYS 1 THROUGH 3)...
A FAST-MOVING LOW PRESSURE SYSTEM BRINGS WIDESPREAD RAIN SHOWERS
FOR THE AK PEN, EASTERN ALEUTIANS AND BRISTOL BAY COASTLINE INTO
TOMORROW EVENING. THIS WILL BE QUICKLY FOLLOWED BY ANOTHER, MORE
EASTERLY MOVING LOW PRESSURE SYSTEM MID- WEEK INTO THURSDAY.
RAIN SHOWERS AND FOG IN THE PRIBILOF ISLANDS AND THE CENTRAL
ALEUTIANS WILL PERSIST AS A LOW PRESSURE SYSTEM BARRELS ONSHORE
TUESDAY. RAIN CONTINUES THROUGH TOMORROW EVENING WITH RAINFALL
AMOUNTS RANGING FROM 0.80" TO 1.10" BY TOMORROW AFTERNOON
EXPECTED. AS THE LOW REMAINS NORTH OF THE PRIBILOFS MOVING TOWARD
CAPE NEWENHAM THE NEXT 36 HOURS, THE HEAVIEST RAINFALL IS EXPECTED
TO FALL ALONG THE BRISTOL BAY COASTLINE FROM KING SALMON TO
DILLINGHAM EASTWARD TO ILIAMNA FROM TOMORROW MORNING TO TOMORROW
EVENING. INITIAL SOUTHERLY WINDS AHEAD OF THE STORM TURN
SOUTHWESTERLY TUESDAY BRINGING PERSISTENT MOISTURE TO THIS AREA.
BY 6:00 PM TUESDAY, MODEL SPREAD IN RAINFALL AMOUNTS FROM THIS
STORM RANGES FROM A 70% OF GREATER THAN 0.75" TO 40% CHANCE OF
GREATER THAN 1.00" OF RAIN. WIND GUSTS UP TO 40 TO 45MPH ARE
LIKELY ALONG THE NORTHERN KUSKOKWIM BAY COAST TUESDAY MORNING
WITH 35 MPH FOR BRISTOL BAY. BRISTOL BAY WILL SEE THE STRONGEST
CORRIDOR OF SOUTHWEST WINDS, UP TO 30 MPH THROUGH THE BAY TUESDAY
AFTERNOON INTO EARLY WEDNESDAY BEFORE WINDS BRIEFLY DIMINISH AHEAD
OF THE NEXT SYSTEM TO MOVE INTO SOUTHWEST ON WEDNESDAY. IN
ADDITION TO THE GUSTY WINDS TUESDAY ACROSS KUSKOKWIM AND BRISTOL
BAYS, EXPECT LARGER WAVES OF AROUND 10 FT IN THE COASTAL WATERS OF
KUSKOKWIM BAY WITH 7 TO 9 FT FOR BRISTOL BAY.
A SECOND SYSTEM WILL IMPACT SOUTHWEST ON WEDNESDAY WITH CONTINUED
WINDY AND RAINY CONDITIONS. MODERATE TO HEAVY RAIN ALONG WITH
GALE- FORCE SOUTHWESTERLY WINDS CAN BE EXPECTED TOMORROW ACROSS
THE WESTERN ALEUTIANS. RAIN ALSO SPREADS EAST TO THE PRIBILOF
ISLANDS BY EARLY WEDNESDAY MORNING AND TO ADAK/ATKA BY LATE
WEDNESDAY MORNING REACHING THE KUSKOKWIM DELTA COAST AND
BRISTOL BAY COAST THURSDAY.
-JOHNSTON
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...STEADY RAIN WILL TAPER OFF LATER THIS EVENING AS LIGHT
WINDS SLOWLY SHIFT AROUND FROM SOUTHWESTERLY TO SOUTHERLY.
VISIBILITY WILL LIKELY IMPROVE TO VFR AS RAIN LETS UP, BUT
LINGERING MOISTURE COULD KEEP CEILINGS IN MVFR RANGE UNTIL LATE
TONIGHT. CEILINGS WILL EVENTUALLY IMPROVE TO VFR OVERNIGHT INTO
TUESDAY MORNING. EXPECT POTENTIAL FOR WINDS BLOWING OUT OF THE
TURNAGAIN ARM TO BEND INTO THE TERMINAL BY TOMORROW AFTERNOON.
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