580
FXUS66 KSEW 090519
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
1019 PM PDT WED APR 8 2026
SYNOPSIS
DRY CONDITIONS WILL CONTINUE ACROSS WESTERN WASHINGTON THROUGH
FRIDAY, WITH A GRADUAL WARMING TREND EXPECTED OVER THE NEXT FEW
DAYS. CLEAR SKIES AND COOL OVERNIGHT TEMPERATURES WILL ALLOW FOR
FROST TO FORM ACROSS PORTIONS OF THE REGION EARLY THURSDAY
MORNING. COOLER TEMPERATURES AND PRECIPITATION CHANCES RETURN
THIS WEEKEND. UNSETTLED CONDITIONS MAY CONTINUE INTO EARLY NEXT
WEEK.
SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/
OVERALL THE WEATHER PATTERN REMAINS FAIRLY STEADY THROUGH FRIDAY
AS DRY, NORTHWESTERLY FLOW ALOFT PREVAILS AS THE RIDGE REMAINS
OFFSHORE AND A CUTOFF LOW PERSISTS INCHES WESTWARD TOWARDS
NORTHERN CALIFORNIA. THE RIDGE AXIS FINALLY PROGRESSES ACROSS
THE AREA EARLY ON FRIDAY AS A TROUGH BEGINS TO DIG INTO THE
OFFSHORE WATERS FROM THE GULF OF ALASKA. ALL THAT SAID, SKIES
WILL REMAIN MOSTLY CLEAR THROUGH EARLY FRIDAY WITH TEMPERATURES
WARMING UP SLIGHTLY EACH DAY. HIGHS TODAY IN THE LOW TO MID 60S,
WITH 50S ACROSS THE NORTHERN SALISH SEA COASTS AND THE
IMMEDIATE PACIFIC COASTLINE. ANOTHER COOL AND CLEAR NIGHT WITH
CALM WINDS WILL ALLOW LOWS TO DROP INTO THE MID 30S. THIS WILL
ALLOW FOR SOME ISOLATED FROST TO DEVELOP, MAINLY ACROSS THE
SOUTHWEST INTERIOR AND LOWER CHEHALIS VALLEY, AND AROUND THE
ARLINGTON AREA IN SNOHOMISH COUNTY. OTHER LOCALIZED AREAS MAY BE
POSSIBLE IN THE INTERIOR WESTERN WHATCOM COUNTY, AND AROUND
FORKS. HIGHS THURSDAY AND FRIDAY IN THE MID 60S TO LOW 70S, WITH
LOWS IN THE LOW TO MID 40S.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
THE AFOREMENTIONED TROUGH WILL CONTINUE TO DIG SOUTHWESTWARD
ALONG THE WEST COAST, MOVING INLAND DOWN TOWARDS NORTHERN
CALIFORNIA. THIS WILL SEND NOT JUST MUCH COOLER TEMPERATURES BUT
ALSO SOME CHANCES FOR RAIN SHOWERS THROUGH THE WEEKEND. MODELS
ARE SHOWING THAT RAIN COULD ARRIVE AS EARLY AS FRIDAY AFTERNOON
OR EVENING ACROSS SOUTHWEST WASHINGTON, BUT THE BETTER CHANCES
TO SEE MORE WIDESPREAD RAIN ACROSS THE AREA WILL BEGIN OVERNIGHT
INTO EARLY SATURDAY MORNING. OFF AND ON PRECIP CHANCES WILL
CONTINUE THROUGH SUNDAY AND INTO MONDAY AS WELL, AT LEAST FOR
THE HIGHER ELEVATIONS, AS THE SYSTEM SLOWLY MOVES INTO THE
SOUTHWESTERN U.S. LOWERING SNOW LEVELS EARLY NEXT WEEK WILL
ALLOW FOR VERY LIGHT SNOW ACCUMULATIONS IN THE MOUNTAINS AND
PASSES. THE ACTIVE PATTERN LOOKS TO CONTINUE INTO THE MIDDLE OF
NEXT WEEK AS ANOTHER TROUGH IS ON ITS HEELS TUESDAY INTO
WEDNESDAY. TEMPERATURES WILL DROP BACK DOWN INTO THE LOW TO MID
50S, WITH LOWS IN THE 40S.
62
AVIATION
HIGH PRESSURE ALOFT REMAINS OFFSHORE, WITH NORTHWEST FLOW OVER
THE REGION TONIGHT BECOMING INCREASINGLY WESTERLY THURSDAY. VFR
CONDITIONS UNDER CLEAR SKIES FOR MOST OF THE AREA, BUT ANOTHER
ROUND OF FOG WILL BE POSSIBLE FOR TERMINALS NEAR THE SOUTH
SOUND AND CHEHALIS RIVER VALLEY (MAINLY IMPACTING KPWT, KOLM,
AND KHQM) ON THURSDAY MORNING. LATEST PROBABILISTIC GUIDANCE
INDICATES A 20 PERCENT CHANCE OF LIFR CONDITIONS BRIEFLY
DEVELOPING FOR THESE TERMINALS BY AROUND 12Z. EXPECT ANY FOG
THAT DOES DEVELOP TO SCATTER BY MIDDAY. LIGHT WINDS OVERNIGHT
WILL REMAIN NORTHERLY AND INCREASING TO 6-10 KT LATE THURSDAY
MORNING.
KSEA...VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. LIGHT
WINDS OVERNIGHT, WITH INCREASING NORTHERLY SURFACE WINDS TO 10
KT LATE THURSDAY MORNING THROUGH THE DAY.
CULLEN
MARINE
NORTH WINDS PERSIST OVER THE COASTAL WATERS THROUGH FRIDAY WITH
HIGH PRESSURE IN PLACE OVER THE NE PACIFIC. A LOW PRESSURE
SYSTEM WILL DEVELOP OVER THE OPEN WATERS ON FRIDAY BEFORE
SWINGING SOUTH AND EAST TOWARDS SOUTHERN OREGON AND NORTHERN
CALIFORNIA. HIGH PRESSURE WILL ONCE AGAIN TAKE ITS PLACE OVER
THE WEST COAST ON MONDAY. A FRONTAL SYSTEM LOOKS TO MOVE THROUGH
THE AREA TUESDAY INTO WEDNESDAY.
OVERALL LITTLE IN THE WAY OF IMPACTFUL WEATHER. THE DIURNAL
CYCLE OF WESTERLY PUSHES DOWN THE STRAIT OF JUAN DE FUCA MAY
START TO DEVELOP OVER THE WEEKEND INTO EARLY NEXT WEEK. SEAS
REMAIN 4 TO 8 FT OVER THE NEXT WEEK.
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HYDROLOGY
NO RIVER FLOODING IS EXPECTED IN THE NEXT SEVEN DAYS.
SEW WATCHES/WARNINGS/ADVISORIES
WA...FROST ADVISORY UNTIL 9 AM PDT THURSDAY FOR DOWNTOWN EVERETT /
MARYSVILLE AREA-FOOTHILLS AND VALLEYS OF PIERCE AND
SOUTHERN KING COUNTIES-FOOTHILLS AND VALLEYS OF THURSTON
AND LEWIS COUNTIES-LOWLANDS OF LEWIS AND SOUTHERN
THURSTON COUNTIES-MIDDLE CHEHALIS RIVER VALLEY-OLYMPIA
AND SOUTHERN PUGET SOUND.
PZ...NONE.
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