646
FXUS66 KSEW 162146
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
246 PM PDT TUE SEP 16 2025
SYNOPSIS
ONSHORE FLOW RETURNS WEDNESDAY ALLOWING FOR
TEMPERATURES TO RETURN TO NEAR NORMAL. CHANCE FOR WIDESPREAD
PRECIPITATION WILL LIKELY RETURN THIS WEEKEND.
SHORT TERM /TONIGHT THROUGH FRIDAY/
STRONG HIGH PRESSURE AND
OFFSHORE FLOW IS GIVING HIGH TEMPS ACROSS WESTERN WA THIS
AFTERNOON. MOST SPOTS ARE IN THE 80S AND CLOSE TO 90 IN THE
FOOTHILLS. DRY, GUSTY, EAST WINDS ARE ALSO BRINGING HUMIDITIES
DOWN AND INTO THE 20S AND 30S FOR CRITICAL FIRE WEATHER
CONDITIONS - A RED FLAG WARNING REMAINS IN EFFECT. BOTH WINDS AND
RHS WILL EASE/IMPROVE THIS EVENING.
A TRANSITION BACK TO ONSHORE FLOW WILL BRING COOLER CONDITIONS TO
THE AREA ON WEDNESDAY. HIGHS WILL DIP BACK DOWN INTO THE 60S AND
70S. A TROUGH MAY BRING SOME LIGHT PRECIP TO THE COAST OTHERWISE
THE REST OF THE REGION WILL REMAIN DRY.
ONSHORE FLOW PREVAILS MOVING THROUGH THE END OF THE WEEK, LEADING
TO NEAR NORMAL CONDITIONS. EXPECT PATCHY MORNING CLOUDS AND
AFTERNOON SUNBREAKS. 33
LONG TERM /SATURDAY THROUGH TUESDAY/
THE NEXT FRONTAL SYSTEM
WILL SHIFT INLAND ON SATURDAY FOR A RETURN OF WET WEATHER. FOR
NOW, THE INTERIOR LOOKS DRY IN THE MORNING WITH RAIN INCREASING
DURING THE AFTERNOON AND EVENING HOURS. THE COAST AND MOUNTAINS
WILL SEE WETTING RAINS. WE REMAIN UNDER COOL, MOIST, ONSHORE FLOW
ON SUNDAY WITH ADDITIONAL LIGHT SHOWERS EXPECTED. FOR MONDAY AND
TUESDAY, A RIDGE BUILDS TO OUR SOUTH WITH ZONAL FLOW OVER WA.
TEMPERATURES ARE TIPPED TOWARD CLIMO WITH A CHANCE OF RAIN AS A
WEAK SYSTEM MOVES INTO B.C. 33
AVIATION
THERMALLY INDUCED TROUGH OFF THE COAST WITH LOW LEVEL
OFFSHORE FLOW. THE TROUGH WILL SHIFT INLAND ALLOWING TROUGHING
OFFSHORE TO NEAR W WA WITH SOUTHWESTERLY FLOW. VFR CONDITIONS AT
ALL AREA TERMINALS THIS AFTERNOON. MARINE STRATUS WILL START TO
CREEP IN TONIGHT FOR COASTAL TERMINALS (KHQM, KCLM) FOR MVFR/IFR
CONDITIONS. STRATUS LOOKS TO PUSH INLAND, LIKELY NEARING KOLM/KPWT
FOR MVFR/IFR CONDITIONS AS WELL.. WITH THE OTHER INTERIOR
TERMINALS LIKELY STAYING CLEAR OF STRATUS DEVELOPMENT. AREAS ALONG
THE COAST WILL FIND IT HARD TO BREAK OUT OF STRATUS WHILE
INTERIOR TERMINALS WILL REMAIN VFR THROUGH THE DAY.
KSEA...VFR CONDITIONS AT THE TERMINAL THIS AFTERNOON. N/NW WINDS 5
TO 10 KNOTS THIS AFTERNOON SWITCHING TO SOUTHERLY WINDS AROUND
02Z-05Z, REMAINING THE SAME SPEED. VFR WILL LIKELY CONTINUE
WEDNESDAY MORNING, WITH A LOW CHANCE (15%) OF MVFR/IFR CONDITIONS
IF MARINE STRATUS REACHES THE TERMINAL.
MARINE
A THERMALLY INDUCED TROUGH WILL MOVE INLAND TONIGHT,
WITH A WEAK SYSTEM OFFSHORE NEARING THE COASTAL WATERS. THE WEAK
SYSTEM WILL CROSS OVER THE AREA TONIGHT, WITH ONSHORE FLOW
RESUMING. SURFACE HIGH PRESSURE WILL RESIDE OVER THE COASTAL
WATERS WITH LOWER PRESSURE INLAND. A SMALL CRAFT ADVISORY HAS BEEN
ISSUED FOR WESTERLIES IN THE STRAIT OF JUAN DE FUCA FOR WEDNESDAY
AFTERNOON. SMALL CRAFT NORTHWESTERLIES WILL START OVER THE
COASTAL WATERS LATE WEDNESDAY INTO THURSDAY. ONSHORE FLOW WILL
CONTINUE INTO THE WEEKEND.
COMBINES SEAS 4 TO 6 FEET THIS AFTERNOON WILL BUILD TO 8 TO 10
FEET LATE WEDNESDAY CONTINUING INTO THURSDAY. SEAS WILL BE A BIT
STEEPER WITH A DOMINANT PERIOD OF 10 TO 11 SECONDS. SEAS WILL
SUBSIDE BY LATE FRIDAY.
MAZURKIEWICZ
FIRE WEATHER
CRITICAL FIRE WEATHER CONDITIONS CONTINUE WITH
HOT, DRY AND WINDY THRESHOLDS ACROSS WESTERN WA. A RED FLAG
WARNING REMAINS IN EFFECT THIS EVENING.
SEW WATCHES/WARNINGS/ADVISORIES
WA...RED FLAG WARNING UNTIL 11 PM PDT THIS EVENING FOR BLACK HILLS
AND SOUTHWEST INTERIOR LOWLANDS-NORTHEAST PUGET SOUND
LOWLANDS GENERALLY BELOW 1500 FEET-SOUTHEAST PUGET SOUND
LOWLANDS GENERALLY BELOW 1500 FEET-WEST SLOPES OF THE
CENTRAL CASCADES GENERALLY ABOVE 1500 FEET-WEST SLOPES OF
THE NORTH CASCADES GENERALLY ABOVE 1500 FEET.
WIND ADVISORY UNTIL MIDNIGHT PDT TONIGHT FOR FOOTHILLS AND
VALLEYS OF CENTRAL KING COUNTY-FOOTHILLS AND VALLEYS OF
PIERCE AND SOUTHERN KING COUNTIES-FOOTHILLS AND VALLEYS OF
SNOHOMISH AND NORTHERN KING COUNTIES.
PZ...SMALL CRAFT ADVISORY FROM 2 PM WEDNESDAY TO 2 AM PDT THURSDAY
FOR CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-EAST
ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY FROM 2 PM WEDNESDAY TO 5 PM PDT THURSDAY
FOR COASTAL WATERS FROM CAPE FLATTERY TO JAMES ISLAND 10 TO
60 NM-COASTAL WATERS FROM CAPE FLATTERY TO JAMES ISLAND OUT
10 NM-COASTAL WATERS FROM JAMES ISLAND TO POINT GRENVILLE
10 TO 60 NM-COASTAL WATERS FROM JAMES ISLAND TO POINT
GRENVILLE OUT 10 NM-COASTAL WATERS FROM POINT GRENVILLE TO
CAPE SHOALWATER 10 TO 60 NM-COASTAL WATERS FROM POINT
GRENVILLE TO CAPE SHOALWATER OUT 10 NM.
SMALL CRAFT ADVISORY UNTIL 2 PM PDT THIS AFTERNOON FOR COASTAL
WATERS FROM POINT GRENVILLE TO CAPE SHOALWATER 10 TO 60 NM-
COASTAL WATERS FROM POINT GRENVILLE TO CAPE SHOALWATER OUT
10 NM.
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