401
FXUS66 KSEW 051639
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
939 AM PDT SAT SEP 5 2026
SYNOPSIS
LOW PRESSURE WILL BRING SHOWERS AND THUNDERSTORMS TO
WESTERN WASHINGTON THIS WEEKEND, WITH DRIER WEATHER MOVING INTO
NEXT WEEK. OFFSHORE FLOW WILL LEAD TO SLIGHTLY WARMER WEATHER
MIDWEEK. A FRONT AND TROUGH WILL BRING COOLER WEATHER AND A
CHANCE OF SHOWERS TOWARD THE END OF THE WEEK.
SHORT TERM /TODAY THROUGH MONDAY/
AN UPPER LEVEL LOW WILL SPIN OVER THE PAC NW TODAY WITH ANOTHER
ROUND OF AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS OVER
WESTERN WASHINGTON. CELLS WILL INITIALLY FORM OVER THE CASCADES
THEN DRIFT WEST OVER THE LOWLANDS, SIMILAR TO WHAT WAS OBSERVED
YESTERDAY. SHOWERS AND THUNDERSTORMS WILL DECREASE TOWARD SUNSET
THIS EVENING. WE WILL SEE A FEW SUNBREAKS IN BETWEEN SHOWERS
WITH AFTERNOON HIGHS AROUND 70. THE COAST WILL BE COOLER AND IN
THE 60S.
THE UPPER LOW CONTINUES TO WOBBLE OVERHEAD ON SUNDAY BUT SHOWERS
WILL MOSTLY STICK OVER THE MOUNTAINS. THE AIR MASS REMAINS
SLIGHTLY UNSTABLE FOR ISOLATED MOUNTAIN THUNDERSTORMS AS WELL.
WITH LIGHTER/WEAKER STEERING FLOW, THE STORMS WILL BE SLOW-MOVING
WITH THE POTENTIAL FOR HIGHER PRECIPITATION TOTALS (ESPECIALLY
OVER THE SOUTHERN CASCADES).
THE UPPER LOW SHIFTS FARTHER EAST AND INLAND ON MONDAY WITH JUST
ISOLATED SHOWERS OVER THE CASCADES. LOW LEVEL ONSHORE FLOW WILL
BE STRONGER FOR MORNING CLOUDS AND LATE AFTERNOON SUNBREAKS. 33
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
WESTERN WA LIES IN BETWEEN WEATHER SYSTEMS NEXT WEEK WITH BROAD
LOW PRESSURE OVER WESTERN CANADA AND A CUTOFF LOW (ASSOCIATED
WITH HURRICANE MARIE) WELL OFFSHORE ALONG 135W. EAST/OFFSHORE
FLOW WILL LEAD TO SLIGHTLY WARMER WEATHER IN THE MID TO UPPER
70S BOTH WEDNESDAY AND THURSDAY. EXPECT LOWS IN THE 50S. THE
CANADIAN LOW WILL BRING TROUGHING OVER THE AREA BY FRIDAY FOR
COOLER WEATHER AND A CHANCE OF SHOWERS. 33
AVIATION
VARIABLE FLOW ALOFT CONTINUES AS AN UPPER LEVEL LOW MOVES
SLOWLY OVER WESTERN WASHINGTON. SURFACE WINDS LARGELY LIGHT AND
VARIABLE THIS EARLY MORNING BEFORE FAVORING A NORTH TO
NORTHEASTERLY DIRECTION LATER THIS MORNING AND INTO THIS
EVENING. LIGHT AND VARIABLE WINDS EXPECTED TO RETURN TONIGHT.
VFR CONDITIONS PERSIST AT MOST TERMINALS, THE EXCEPTION BEING
BLI AND OLM AS SOME LOW CLOUDS/FOG PUSH CONDITIONS DOWN TO
IFR/LIFR, BUT WILL RETURN TO VFR CONDITIONS BY NOON TODAY.
SCATTERED SHOWERS WITH ISOLATED THUNDERSTORMS POSSIBLE AGAIN
TODAY BUT PROBABILITIES DO NOT FAVOR TAF INCLUSION AT THIS TIME.
KSEA...VFR CONDITIONS IN PLACE AND EXPECTED TO REMAIN THAT WAY FOR
THE TAF PERIOD. THUNDERSTORMS ARE POSSIBLE IN THE CASCADES THIS
AFTERNOON, AND AT THIS TIME DO NOT HAVE INDICATION OF GOING
NEAR THE TERMINAL AND WILL LEAVE IT OUT OF TAF INCLUSION. WINDS
LIGHT AND VARIABLE THIS MORNING, TURNING MORE NORTHERLY BY THIS
AFTERNOON BEFORE SHIFTING NORTHEASTERLY AROUND 00Z. SPEEDS
INCREASING TO AROUND 5-10 KTS THIS AFTERNOON.
18/MAZURKIEWICZ
MARINE
NO SIGNIFICANT MARINE CONDITIONS EXPECTED ON THE WHOLE,
WITH WINDS AND SEAS LARGELY REMAINING SHORT OF ANY ADVISORY
CRITERIA. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL BE
POSSIBLE AGAIN TODAY AS THE UPPER LEVEL LOW OVER THE REGION HAS
MOVED VERY LITTLE. NORTHERLY WINDS EXPECTED OVER THE WATERS THIS
WEEKEND INTO NEXT WEEK. A MARGINAL WESTERLY PUSH THROUGH THE STRAIT
OF JUAN DE FUCA AROUND MONDAY LOOKS TO BE THE NEXT POTENTIAL PERIOD
OF ADVISORY STRENGTH CONDITIONS. SEAS MAINLY 3 TO 5 FEET THIS
WEEKEND AND INTO THE START OF NEXT WEEK.
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
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