068
FXUS66 KSEW 180936
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
236 AM PDT FRI SEP 18 2026
SYNOPSIS
THE RETURN OF ONSHORE FLOW TO THE AREA WILL BRING MORE SEASONABLE
TEMPERATURES AND MORNING CLOUDS TO WESTERN WASHINGTON DAILY
THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK. UPPER LEVEL
TROUGHING DEVELOPING OVER THE NORTHEASTERN PACIFIC NEXT WEEK
WILL OPEN THE DOOR FOR SOME SYSTEMS TO MAKE THEIR WAY INTO THE
REGION, WITH RAIN CHANCES INCREASING MID TO LATE WEEK.
SHORT TERM /TODAY THROUGH SUNDAY/
AN UPPER LEVEL RIDGE WILL SHIFT EASTWARD TODAY AND OVER THE
WEEKEND AS AN UPPER LEVEL LOW OVER EASTERN OR CONTINUES TO MAKE
ITS WAY EASTWARD OUT OF THE REGION. ONSHORE FLOW WILL CONTINUE
IN THE LOW LEVELS THROUGH THE WEEKEND, BRINGING RATHER SEASONABLE
TEMPERATURES AND DAILY MORNING CLOUD COVER TO WESTERN WASHINGTON.
STRATUS MAY LINGER ALONG THE COAST AT TIMES OVER THE WEEKEND,
PARTICULARLY TODAY AND AGAIN ON SATURDAY, BUT EXPECT STRATUS TO
SCATTER EACH DAY ACROSS THE INTERIOR FOR SOME AFTERNOON SUN.
AFTERNOON HIGHS WILL BE IN THE LOW TO MID 70S ACROSS THE INTERIOR
AND IN THE MID 60S ALONG THE COAST. MORNING LOWS WILL BE IN THE
UPPER 40S TO LOW 50S.
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
ENSEMBLES HINT AT THE PATTERN CHANGING NEXT WEEK AS UPPER LEVEL
TROUGHING DEVELOPS ACROSS THE NORTHEASTERN PACIFIC. WHILE MOSTLY
DRY CONDITIONS LOOK TO PERSIST ACROSS WESTERN WASHINGTON THROUGH
THE FIRST HALF OF THE WEEK, THE DEVELOPMENT OF SOUTHWEST FLOW
ALOFT OVER THE AREA WILL OPEN THE DOOR FOR SYSTEMS TO MAKE IT
INTO WESTERN WASHINGTON MID TO LATE WEEK. AT THIS TIME, RAIN
CHANCES LOOK TO INCREASE MIDWEEK AS A WEAK SYSTEM BRUSHES THE
REGION, WITH MORE WIDESPREAD RAIN CHANCES FOLLOWING LATE WEEK.
HIGH TEMPERATURES WILL GENERALLY TREND IN THE UPPER 60S TO LOW
70S ACROSS THE INTERIOR AND IN THE 60S ALONG THE COAST. MORNING
LOWS WILL BE IN THE UPPER 40S TO MID 50S.
14
AVIATION
NORTHWEST FLOW ALOFT WILL TURN WESTERLY TONIGHT AS AN UPPER RIDGE
AXIS JUST OFFSHORE SHIFTS EASTWARD ACROSS THE AREA. THE LOW LEVEL
FLOW IS LIGHT ONSHORE. COASTAL STRATUS IS MAKING PROGRESS INLAND
THROUGH THE CHEHALIS GAP AND IFR CONDITIONS WILL LIKELY ENCOMPASS
MUCH OF THE INTERIOR LOWLANDS FROM AROUND KPAE SOUTHWARD FOR A FEW
HOURS LATER THIS MORNING BEFORE BURNING BACK TOWARD THE COAST. VFR
CONDITIONS WILL PREVAIL ACROSS THE INTERIOR THIS AFTERNOON WITH
STRATUS MAKING A RETURN AND LIKELY WITH GREATER COVERAGE ON SATURDAY
MORNING.
KSEA...IFR STRATUS IS ON TRACK TO ARRIVE AT THE TERMINAL BY AROUND
12Z THIS MORNING AND WILL LIKELY PERSIST THROUGH 18Z OR SO BEFORE
LIFTING AND SCATTERING OUT TO VFR FOR THE AFTERNOON. STRATUS WILL
RETURN AGAIN OVERNIGHT TONIGHT AND LIKELY TAKE LONGER TO CLEAR ON
SATURDAY. SURFACE WINDS SOUTH TO SOUTHWESTERLY 4 TO 8 KNOTS.
27
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.
27
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.
14
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
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