990
FXUS66 KSEW 122137
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
237 PM PDT MON OCT 12 2026
SYNOPSIS
A WEATHER SYSTEM MOVING INTO BRITISH COLUMBIA WILL BRUSH WESTERN
WASHINGTON ON TUESDAY, BRINGING SHOWERS TO THE PACIFIC COAST AND
THE NORTH INTERIOR INTO WEDNESDAY. A RIDGE OF HIGH PRESSURE WILL
REBUILD OVER THE AREA WEDNESDAY INTO THURSDAY, BEFORE PUSHING
INLAND ON FRIDAY. WARM TEMPERATURES ARE EXPECTED THURSDAY AND
FRIDAY AS OFFSHORE FLOW DEVELOPS. A WEAK SYSTEM WILL MOVE INTO
THE AREA ON SATURDAY, FOLLOWED BY A STRONGER SYSTEM SUNDAY INTO
MONDAY.
SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/
SATELLITE IMAGERY SHOWS SUNNY AND CLEAR SKIES ACROSS WESTERN
WASHINGTON THIS AFTERNOON, WITH AREAS OF PATCHY FOG THIS MORNING
HAVING DISSIPATED. HIGHS ARE STILL ON TRACK TO BE CLOSE TO SEASONAL
NORMS TODAY, AND ARE EXPECTED TO TOP OUT IN THE UPPER 50S TO MID
60S ACROSS THE AREA. DRY CONDITIONS WILL CONTINUE INTO TONIGHT
AS AN UPPER LEVEL RIDGE OVER THE REGION FLATTENS. A WEATHER
SYSTEM MOVING INTO BRITISH COLUMBIA TONIGHT INTO TUESDAY WILL
BRING INCREASING MID TO HIGH CLOUD COVER TO THE AREA OVERNIGHT,
BRINGING WARMER OVERNIGHT LOW TEMPERATURES TO MUCH OF WESTERN
WASHINGTON AND LIMITING THE POTENTIAL FOR FOG AND FROST FORMATION
OVERNIGHT. OVERNIGHT LOWS ARE EXPECTED TO BE IN THE UPPER 30S
TO MID 40S.
THE SYSTEM MOVING INTO BRITISH COLUMBIA WILL BRUSH WESTERN
WASHINGTON TUESDAY INTO EARLY WEDNESDAY AS THE RIDGE CONTINUES
TO WEAKEN AND THE SYSTEM SAGS SOUTHWARD. THIS WILL BRING SOME
LIGHT SHOWER ACTIVITY TO THE NORTHWESTERN PORTION OF THE AREA-
MAINLY TO THE PACIFIC COAST, THE WESTERN SLOPES OF THE OLYMPICS,
AND AREAS FROM KING COUNTY NORTHWARD. OVERALL RAINFALL AMOUNTS
WILL BE RATHER LIGHT, WITH AREAS ACROSS THE NORTHERN INTERIOR
LIKELY ONLY GETTING A FEW HUNDREDTHS OF AN INCH OF RAIN. THE
HIGHEST AMOUNTS WILL BE ALONG THE NORTH COAST, WHERE GENERALLY A
QUARTER OF AN INCH TO HALF AN INCH OF RAIN WILL BE POSSIBLE.
HIGHS ON TUESDAY WILL BE IN THE MID 50S TO MID 60S.
AN UPPER LEVEL RIDGE WILL THEN BUILD BACK INTO THE PACIFIC
NORTHWEST ON WEDNESDAY, WITH SHOWERS EXPECTED TO TAPER
THROUGHOUT THE DAY. HIGHS ARE EXPECTED TO BE IN THE LOWER TO
MID 60S ACROSS WESTERN WASHINGTON WITH MOSTLY CLOUDY CONDITIONS
IN THE MORNING BECOMING PARTLY CLOUDY BY THE AFTERNOON HOURS.
LONG TERM /THURSDAY THROUGH MONDAY/
GUIDANCE REMAINS IN STRONG AGREEMENT WITH THE UPPER LEVEL RIDGE
BUILDING OVER THE REGION ON THURSDAY. A THERMAL TROUGH WILL ALSO
BUILD NORTHWARD ALONG THE COAST AND WILL TURN THE LOW LEVEL
FLOW OFFSHORE, HELPING TO WARM AFTERNOON HIGHS INTO THE MID 60S
TO MID 70S ACROSS THE AREA. FRIDAY WILL BE THE WARMEST DAY OF
THE WEEK AS THE RIDGE AXIS PUSHES FURTHER INLAND AND OFFSHORE
FLOW PERSISTS THROUGH THE MORNING HOURS. HIGHS WILL CLIMB A
DEGREE OR TWO AND ARE AGAIN EXPECTED TO BE IN THE MID 60S TO
MID 70S- ROUGHLY 5 TO 10 DEGREES ABOVE NORMAL ACROSS THE AREA.
OVERNIGHT LOWS BOTH THURSDAY AND FRIDAY WILL BE IN THE MID 40S
TO LOW 50S.
A DISSIPATING FRONTAL SYSTEM THEN LOOKS TO MOVE INTO THE AREA ON
SATURDAY AS THE RIDGE AXIS PUSHES FURTHER TO THE EAST. THE BEST
CHANCES FOR RAIN REMAIN ALONG THE PACIFIC COAST AND ACROSS THE
NORTH CASCADES AS THE SYSTEM MOVES OVER THE AREA. A STRONGER,
MORE ORGANIZED FRONTAL SYSTEM THEN LOOKS TO MOVE THROUGH THE
REGION SUNDAY INTO MONDAY, BRINGING MORE WIDESPREAD CHANCES OF
RAIN AND BREEZY WINDS TO WESTERN WASHINGTON. A DUSTING OF SNOW
FOR THE HIGHER PEAKS WILL ALSO BE POSSIBLE ON MONDAY AS SNOW
LEVELS DROP TO 5000-5500 FT. HIGHS WILL COOL OVER THE WEEKEND AS
CONDITIONS BECOME MORE UNSETTLED AND ONLY LOOK TO TOP OUT IN
THE UPPER 50S TO MID 60S. OVERNIGHT LOWS WILL GENERALLY BE IN
THE 40S AND 50S.
14
AVIATION
WIDESPREAD VFR TODAY WITH CLEAR SKIES. CLOUD COVER WILL START TO
INCREASE THIS EVENING ALONG THE COAST AND SPREAD INTO THE INTERIOR
OVERNIGHT. CEILINGS WILL GRADUALLY DETERIORATE ALONG THE COASTLINE
OVERNIGHT INTO TUESDAY MORNING, WITH MVFR CEILINGS EXPECTED BY THE
AFTERNOON. OTHERWISE, INTERIOR TERMINALS EXPECTED TO REMAIN VFR
TUESDAY. NORTHERLY SURFACE WINDS WILL SHIFT SOUTHERLY TUESDAY
MORNING.
KSEA...VFR TODAY WITH CLEAR SKIES. INCREASING CLOUD COVER ON
TUESDAY, BUT CONDITIONS EXPECTED TO REMAIN VFR. INCREASING CHANCES
FOR MVFR CEILINGS TOWARDS THE END OF THE THE TAF PERIOD.
NORTHWESTERLY WINDS AROUND 5 KNOTS THIS AFTERNOON. WINDS WILL BECOME
LIGHT AND VARIABLE THIS EVENING BEFORE SHIFTING SOUTHEASTERLY BY
05Z.
MARINE
WEAK PRESSURE GRADIENTS WILL PRODUCE LITTLE IN THE WAY OF WIND
ACROSS AREA WATERS TODAY. A WEAK SURFACE RIDGE WILL SHIFT INLAND ON
TUESDAY AS A FRONTAL SYSTEM APPROACHES THE OFFSHORE WATERS WITH
WINDS SHIFTING TO THE E/SE ACROSS MUCH OF THE WATERS. A WEAK COLD
FRONT WILL REACH THE AREA ON WEDNESDAY WITH POSSIBLE HEADLINES FOR
LOW END SMALL CRAFT ADVISORY WINDS ACROSS PORTIONS OF THE COASTAL
WATERS AND THE WEST ENTRANCE TO THE STRAIT. LATEST PROBABILITIES
SHOW THERE IS A 65-90% CHANCE FOR SMALL CRAFT WIND GUSTS. HIGH
PRESSURE REBUILDS ACROSS THE WATERS ON THURSDAY WITH THE FLOW
TURNING NORTHERLY OR WEAKLY OFFSHORE AS THERMALLY INDUCED LOW
PRESSURE EXPANDS NORTHWARD ACROSS WESTERN OREGON. ANOTHER FRONT IS
EXPECTED TO REACH THE WATERS FRIDAY NIGHT OR SATURDAY WITH POSSIBLE
HEADLINES FOR WINDS AND/OR STEEPENING SEAS ACROSS THE COASTAL
WATERS. ADDITIONALLY, GUIDANCE INDICATES POSSIBLE HEADLINES FOR THE
STRAIT ON SATURDAY WITH GUSTS HAVING A 50-60% CHANCE OF REACHING
SMALL CRAFT THRESHOLDS.
27/29
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
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