945
FXUS66 KSEW 110357
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
857 PM PDT WED SEP 10 2025
SYNOPSIS
BROAD UPPER LEVEL TROUGHING WILL SLOWLY SLIDE EAST
THURSDAY AND FRIDAY, BRINGING MOSTLY DRY CONDITIONS TO THE
REGION THAT WILL PERSIST INTO SATURDAY. BY SUNDAY, THE NEXT
WEATHER SYSTEM WILL BRING A CHANCE FOR PRECIPITATION BACK TO THE
REGION.
SHORT TERM /TONIGHT THROUGH SATURDAY/
MAINLY CLEAR SKIES
ACROSS THE INTERIOR THIS EVENING WITH STRATUS MOVING INTO THE
SOUTHWEST INTERIOR AND STRAIT OF JUAN DE FUCA WITH ONSHORE FLOW.
STRATUS WILL SPREAD INTO PUGET SOUND TONIGHT INTO THURSDAY
MORNING. NO MAJOR FORECAST UPDATES THIS EVENING. PREVIOUS
DISCUSSION BELOW.
FAIRLY QUIET CONDITIONS TODAY. LOW LEVEL STRATUS CONTINUES TO
RETREAT TOWARD THE COAST THIS AFTERNOON. THE ONLY ADDITIONAL
CONCERN IS A 20-30% CHANCE OF SHOWERS AND 10-15% CHANCE OF
THUNDERSTORMS ACROSS THE CENTRAL/SOUTHERN CASCADES THIS
AFTERNOON AND EVENING.
AS WE MOVE INTO THURSDAY, UPPER LEVEL RIDGING WILL BECOME THE
DOMINANT FEATURE. WE WILL SEE AN INCREASE IN MARINE STRATUS
THURSDAY MORNING AS WELL AS THE POTENTIAL FOR MORE WIDESPREAD
FOG THROUGH AT LEAST THE FIRST PART OF THE DAY. HOWEVER, THIS
HIGH PRESSURE WILL ALSO BRING DRIER CONDITIONS AND SEASONABLE
TEMPERATURES THAT WILL PERSIST THROUGH SATURDAY.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
FORECAST
CONFIDENCE IN THE DETAILS BEGINS TO WANE AS WE GET INTO SATURDAY
NIGHT AND SUNDAY. THERE HAS BEEN A TREND TOWARDS A MORE
PROGRESSIVE FRONTAL SYSTEM IMPACTING THE REGION SUNDAY, BRINGING
A QUICK SHOT OF PRECIPITATION AND A SLIGHT CHANCE OF
THUNDERSTORMS. THEN WE MAY RINSE AND REPEAT WITH TEMPORARY HIGH
PRESSURE EARLY NEXT WEEK.
-WOLCOTT-
AVIATION
UPPER LEVEL LOW CENTERED OVER NORTHERN CALIFORNIA WILL
SLOWLY MOVE EAST TONIGHT AND THURSDAY. TEMPORARY UPPER LEVEL RIDGE
BUILDING INTO WESTERN WASHINGTON THURSDAY NIGHT. NORTHEASTERLY
FLOW ALOFT BECOMING WESTERLY THURSDAY NIGHT. LIGHT ONSHORE FLOW IN
THE LOWER LEVELS.
IFR/LIFR STRATUS ALREADY COVERING MOST OF THE LOWLANDS WEST OF THE
PUGET SOUND AND THE I-5 CORRIDOR IN SOUTHWEST WASHINGTON. STRATUS
ALREADY DOWN THE STRAIT OF JUAN DE FUCA AS WELL APPROACHING
WHIDBEY ISLAND. STRATUS WILL CONTINUE TO MOVE INLAND TONIGHT
GETTING EAST OF THE PUGET SOUND AROUND 12Z. STRATUS DISSIPATING
BACK TO THE COAST 18Z-20Z WITH CLEAR SKIES OVER THE INTERIOR AFTER
20Z.
KSEA...CLEAR SKIES OVERNIGHT. POSSIBLE BACK BUILDING STRATUS DECK
MOVING OFF CASCADES WITH CEILINGS NEAR 4000 FEET GETS TO THE
TERMINAL BEFORE THE LIFR STRATUS DOES AROUND 13Z. STRATUS LIFTING
TO IFR AROUND 16Z AND TO MVFR AROUND 18Z BEFORE SCATTERING OUT
19Z-20Z. CLEAR SKIES INTO THURSDAY NIGHT. LIGHT AND VARIABLE WIND
BECOMING SOUTHWESTERLY 4 TO 6 KNOTS AROUND 12Z. WINDS TRYING TO
COME AROUND TO NORTHWEST 22Z-02Z BUT LIKELY ENDING UP IN THE
250-280 DEGREE RANGE. FELTON
MARINE
WEAK HIGH PRESSURE OVER THE WATERS WITH LOWER PRESSURE
EAST OF THE CASCADES WILL KEEP ONSHORE FLOW PATTERN GOING THROUGH
FRIDAY NIGHT. FRONT MOVING INTO THE COASTAL WATERS SATURDAY AND
INLAND SUNDAY. HIGH PRESSURE REDEVELOPS AGAIN FOR THE FIRST PART
OF NEXT WEEK.
SMALL CRAFT ADVISORY WESTERLY WINDS IN THE CENTRAL AND EASTERN
STRAIT OF JUAN DE FUCA THURSDAY NIGHT.
SEAS WILL RANGE 4-7 FT, THEN RISE TO 6-8 FT THROUGH THE WEEKEND
(LOW CHANCE FOR 10 FT WAVES AT THIS POINT), BUT WILL DECREASE BACK
TO 3-5 FT EARLY NEXT WEEK. FELTON
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 6 PM THURSDAY TO 2 AM PDT FRIDAY FOR
CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE
U.S. WATERS STRAIT OF JUAN DE FUCA.
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