865
FXUS66 KSEW 190353
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
853 PM PDT FRI SEP 18 2026
SYNOPSIS
SEASONABLE CONDITIONS WITH MORNING CLOUDS WILL SETTLE INTO THE
REGION INTO NEXT AS ONSHORE FLOW CONTINUES, WITH LITTLE CHANGE
DAY TO DAY.
SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/
AN UPPER LEVEL RIDGE WILL CONTINUE TO PROGRESS EASTWARD TODAY,
WITH SOUTHWEST FLOW ALOFT AND ONSHORE FLOW AT THE SURFACE. THIS
PATTERN WILL CONTINUE THROUGH THE WEEKEND AS A SERIES OF
WEATHER SYSTEMS PASS TO THE NORTH, WITH LITTLE CHANGE DAY TO DAY
ACROSS WESTERN WASHINGTON. SEASONABLE TEMPERATURES WILL SETTLE
INTO THE REGION, WITH HIGHS GENERALLY IN THE UPPER 60S TO LOWER
70S AND LOWS IN THE UPPER 40S TO LOWER 50S. ONSHORE PUSHES WILL
ALSO BRING MARINE STRATUS INLAND EACH MORNING TO VARYING
DEGREES, WITH SUNSHINE RETURNING TO MOST INLAND AREAS EACH
AFTERNOON.
LONG TERM /MONDAY THROUGH FRIDAY/
THIS FALL-LIKE PATTERN IS FAVORED TO CONTINUE INTO EARLY NEXT
WEEK AS MODELS HAVE BACKED OFF ON INCOMING PRECIPITATION. THERE
WILL LIKELY BE LITTLE CHANGE ONCE AGAIN DAY TO DAY THROUGH AT
LEAST TUESDAY. MODELS HAVE CONTINUED TO TREND DRIER INTO THE
MIDDLE OF NEXT WEEK, AND CONDITIONS MAY REMAIN STEADY THROUGH
NEXT FRIDAY. HOWEVER, FORECAST CONFIDENCE TOWARDS THE END OF THE
PERIOD REMAINS LOW.
15
AVIATION
HIGH PRESSURE WILL BUILD OFFSHORE INTO SATURDAY. THE ONSHORE
PUSH TONIGHT WILL BRING WIDESPREAD MARINE STRATUS INLAND
OVERNIGHT. CONFIDENCE/PROBABILITIES HAVE INCREASED FOR MORE
WIDESPREAD LIFR CONDITIONS (BOTH CEILINGS AND VISIBILITIES) WITH
THIS PUSH - ESPECIALLY BETWEEN 13 AND 17Z SATURDAY MORNING. THE
FOG AND LOWER CEILINGS WILL LIKELY BE MORE WIDESPREAD AND
DEEPER COMPARED TO THIS MORNING, LIKELY LASTING THROUGH 20-22Z
BEFORE CLEARING/BECOMING VFR IN THE AFTERNOON. WINDS WILL BE
LIGHT OUT OF THE SOUTHWEST 4-8 KT (A FEW SPOTS WILL SEE CALM OR
LIGHT/VARIABLE WINDS OVERNIGHT).
KSEA...VFR THROUGH THE EVENING, THEN MARINE STRATUS LIKELY FROM
12Z TO 20Z SATURDAY. THE LOWEST CEILINGS/VISIBILITIES WILL BE
FROM 14Z-17Z, WHERE THE CHANCE OF LIFR CONDITIONS PEAK IN THE
FORECAST. WINDS SOUTHWEST 4-8 KT.
HPR
MARINE
ONSHORE FLOW WILL PERSIST INTO NEXT WEEK AS A SERIES OF SYSTEMS PASS
WELL NORTH OF THE AREA. THE ONSHORE FLOW WILL INCREASE SOMEWHAT
EARLY NEXT WEEK AS WEAK FRONTAL SYSTEMS BEGIN TO CLIP THE COASTAL
WATERS. NBM PROBABILITIES FOR SCA GUSTS ARE INCREASING TO 30-60%
THROUGHOUT THE CENTRAL/EASTERN STRAIT OF JUAN DE FUCA SUNDAY NIGHT
INTO MONDAY MORNING AND 60-80% ON MONDAY EVENING.
FIRE WEATHER
ONSHORE FLOW WILL BRING COOLER TEMPERATURES, CLOUD COVER, AND
INCREASED MOISTURE TO THE AREA TODAY THROUGH THE WEEKEND, HELPING
TO MINIMIZE FIRE WEATHER CONCERNS. FIRE WEATHER CONCERNS WILL
REMAIN MINIMAL THROUGH THE NEXT WEEK WITH COOLER TEMPERATURES
AND CHANCES OF PRECIPITATION INCREASING MID TO LATE WEEK.
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
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