446
FXUS66 KSEW 071638
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
938 AM PDT MON SEP 7 2026
SYNOPSIS
LOW PRESSURE WILL BRING ADDITIONAL SHOWERS TO
PORTIONS OF WESTERN WASHINGTON TODAY, WITH DRIER AND WARMER
WEATHER MOVING INTO TUESDAY AND WEDNESDAY. A PAIR OF SYSTEMS
WILL BRING MORE SHOWERS AND SLIGHTLY COOLER WEATHER TOWARD THE
END OF THE WEEK AND INTO THE WEEKEND.
SHORT TERM /TODAY THROUGH WEDNESDAY/
WATER VAPOR IMAGERY CONTINUES TO SHOW BROAD UPPER LEVEL
TROUGHING OVER WESTERN WASHINGTON THIS MORNING, THOUGH ON THE
BACK END WHILE THE AXIS OF THE TROUGH CONTINUES TO SHIFT EAST
OVER THE INTERMOUNTAIN WEST. A FEW LOCALIZED SHOWERS CONTINUE
OVER THE NORTHERN INTERIOR WITH AN ISOLATED THUNDERSTORM OVER
WESTERN WHATCOM COUNTY, BUT THIS SHOULD DISSIPATE LATER THIS
MORNING FOR MOSTLY DRY CONDITIONS ACROSS THE AREA FOR THIS
AFTERNOON. THE MARINE LAYER THIS MORNING WILL SLOWLY LIFT THIS
MORNING, KEEPING TEMPERATURES BELOW AVERAGE TODAY, WITH HIGHS
IN THE UPPER 60S TO LOW 70S.
THE UPPER LOW DEPARTS TO THE N/NE ON TUESDAY, LEAVING WESTERN WA
DRY AND MILD. THE AIR MASS WILL BE A LITTLE WARMER WITH HIGHS IN
THE 70S. THE COAST WILL BE COOLER AND IN THE 60S.
WEDNESDAY WILL BE A FEW DEGREES WARMER WITH WEAK HIGH PRESSURE
AND LIGHT OFFSHORE FLOW. HIGHS IN THE INTERIOR WILL REACH THE
70S TO LOWER 80S. 33/62
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
BROAD LOW PRESSURE OVER WESTERN CANADA WILL SAG SOUTH AND SEND
A TROUGH THROUGH WESTERN WA ON THURSDAY. AS A RESULT, WE'LL SEE
STRONGER ONSHORE FLOW, SLIGHTLY COOLER CONDITIONS, AND A CHANCE
OF SHOWERS (MAINLY IN THE CASCADES). A SECOND SYSTEM WILL SLOWLY
CROSS THE AREA ON FRIDAY AND SATURDAY FOR INCREASING SHOWERS
ACROSS THE BOARD. THE WEATHER LOOKS DRIER EARLY NEXT WEEK AS
OFFSHORE FLOW RETURNS. 33
AVIATION
MVFR CONDITIONS WITH MID TO HIGH CLOUDS ACROSS MOST
PLACES IN THE INTERIOR, WITH SOME PLACES SEEING IFR/LIFR (PWT,
BLI). WIDESPREAD IMPROVEMENT EXPECTED IN THE AFTERNOON AFTER
19Z-21Z. MVFR CEILINGS LIKELY RETURNING TO THE COAST TONIGHT.
SW FLOW THROUGH THIS AFTERNOON WILL TRANSITION NW AFTER 22Z-00Z.
NE WINDS TONIGHT.
KSEA...MVFR CIGS THIS MORNING. IMPROVEMENT TO VFR AFTER 20Z WITH
VFR CONTINUING THROUGHOUT MOST OF THE DAY. SW FLOW THIS MORNING
WILL TRANSITION NW AROUND/AFTER 00Z AT 5-7 KT. WINDS WILL
TRANSITION NE THIS EVENING AFTER 02Z AT SIMILAR SPEEDS.
29/MAZURKIEWICZ
MARINE
A SMALL CRAFT ADVISORY CONTINUES FOR THE CENTRAL AND
EASTERN PORTIONS OF THE STRAIT OF JUAN DE FUCA. WINDS SHOULD
GRADUALLY DECREASE BELOW THRESHOLDS LATER THIS MORNING. BROAD
HIGH PRESSURE WILL SLOWLY BUILD IN MONDAY AND STRENGTHEN THROUGH
THE MIDDLE OF THE WEEK. NORTHWESTERLY WINDS WILL INCREASE OVER
THE COASTAL WATERS ON TUESDAY, BUT ARE EXPECTED TO REMAIN BELOW
SMALL CRAFT THRESHOLDS. STRONGER NORTHWESTERLY WINDS EXPECTED
WEDNESDAY AFTERNOON INTO THURSDAY. LATEST GUIDANCE SUGGESTS A
35-70% CHANCE FOR SMALL CRAFT WINDS OVER THE OUTER COASTAL
WATERS. ADDITIONALLY, THERE IS A 50-75% CHANCE FOR SMALL CRAFT
WINDS THROUGH THE STRAIT OF JUAN DE FUCA.
SEAS 3-6 FEET THROUGH WEDNESDAY. SEAS WILL INCREASE TO 7-10 FEET
TOWARDS THE END OF THE WEEK AND MAY GET STEEP AT TIMES.
29
FIRE WEATHER
NO SIGNIFICANT FIRE WEATHER CONCERNS DEVELOP THROUGH THE START
OF THIS WEEK. WITH WARMER AND DRIER CONDITIONS, EXPECT TO SEE
CONDITIONS TO TREND BACK TO SEASONAL LEVELS OF CONCERN AFTER THE
PREVIOUSLY COOL AND WET PATTERN. THERE'S SOME INDICATION THAT
LIGHT OFFSHORE FLOW DEVELOPS MIDWEEK AND MAY BRING MINIMUM
HUMIDITY VALUES CLOSE TO CRITICAL THRESHOLDS AND AROUND
WEDNESDAY, BUT THE OFFSHORE WINDS DO NOT APPEAR SIGNIFICANTLY
STRONG OR LONG-LIVED TO BRING HIGHER LEVELS OF CONCERN AT THIS
TIME.
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
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