120
FXUS66 KSEW 170342
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
842 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/
NO SIGNIFICANT CHANGE TO
THE FORECAST THIS EVENING. THE PREVIOUS DISCUSSION CAN BE FOUND
BELOW ALONG WITH UPDATES TO THE AVIATION AND MARINE SECTIONS:
STRONG HIGH PRESSURE AND OFFSHORE FLOW IS GIVING HIGH TEMPS
ACROSS WESTERN WA THIS EVENING. 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
FLOW ALOFT REMAINS SOUTHWESTERLY AS THE UPPER LEVEL
RIDGE AXIS REMAINS OVER E WA/N ID. SURFACE FLOW CURRENTLY
TRANSITIONING FROM OFFSHORE TO ONSHORE...WITH WESTERLY WINDS PRESENT
OVER THE WESTERN HALF OF THE OLYMPIC PENINSULA WHILE REMAINING OBS
CONTINUE TO SHOW EITHER LIGHT AND VARIABLE OR EASTERLY TO
SOUTHEASTERLY WINDS. MOST TERMINALS EXPECTED TO SEE SURFACE WINDS
TURN SOUTHERLY THIS EVENING AND REMAIN THAT WAY THROUGHOUT THE TAF
PERIOD.
VFR CONDITIONS IN PLACE FOR ALL TERMINALS THIS EVENING WITH MARINE
STRATUS EXPECTED TO RESULT IN IFR OR LOWER CONDITIONS AT HQM
TONIGHT. MODELS SUGGESTING THAT PWT AND OLM COULD ALSO SEE DEGRADED
CONDITIONS, SO WILL CONTINUE TO EVALUATE THOSE PROSPECTS FOR 06Z
ISSUANCE. IT IS WORTH NOTING THAT THE BEAR GULCH FIRE SAW ACTIVE
CONDITIONS THIS AFTERNOON AND EARLY EVENING...SO THE PROSPECT OF
SMOKE ALOFT NEAR TO AND NORTH OF THE INCIDENT COULD IMPACT FLIGHTS
PASSING THROUGH THE AREA. WIDESPREAD VFR CONDITIONS EXPECTED AGAIN
WEDNESDAY, ALTHOUGH MARINE STRATUS MAY CLING TO THE COAST, LEAVING
LOW-END MVFR TO IFR CONDITIONS IN PLACE OVER HQM.
KSEA...VFR CONDITIONS AT THE TERMINAL FOR THE TAF PERIOD WITH A LOW
CHANCE /15%/ OF MVFR/IFR CONDITIONS IF MARINE STRATUS REACHES THE
TERMINAL. EASTERLY WINDS STILL LINGER BUT SHOULD SWITCH TO MORE
SOUTHERLY TONIGHT AND REMAIN THAT WAY INTO THE AFTERNOON BEFORE
TURNING NORTHWESTERLY. SPEEDS GENERALLY 5-10 KTS, HOWEVER WILL RAMP
UP TO 8=12 KTS WEDNESDAY EVENING.
18/MAZURKIEWICZ
MARINE
A THERMALLY INDUCED TROUGH WILL MOVE INLAND TONIGHT,
WITH A WEAK SYSTEM OFFSHORE NEARING THE COASTAL WATERS. THIS 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 REMAINS IN EFFECT 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/18
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.
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