635
FXUS66 KSEW 202255
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
355 PM PDT FRI MAR 20 2026
SYNOPSIS
A COLD FRONT CONTINUES TO MOVE EAST OF THE CASCADES
THIS AFTERNOON, RESULTING IN A POST-FRONTAL ONSHORE FLOW.
GENERALLY DRIER WEATHER THROUGH MONDAY, WITH THE EXCEPTION BEING
SUNDAY WITH A WEAK SYSTEM MOVING BY TO THE NORTH. ANOTHER SYSTEM
BRINGS LOWLAND RAIN, INCREASING WINDS, AND UPPER ELEVATION
MOUNTAIN SNOWFALL MIDWEEK.
SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/
A POST-FRONTAL
AIRMASS EXISTS ACROSS WESTERN WASHINGTON THIS AFTERNOON. A
CONVERGENCE ZONE IS LOCATED ACROSS PORTIONS OF SNOHOMISH AND
SKAGIT COUNTIES WITH INCREASING WEST WINDS THROUGH THE STRAIT OF
JUAN DE FUCA. THE CZ WILL BE RATHER SHORTER DURATION, AND MOVE
INTO THE CASCADES INTO TONIGHT, WITH ONLY LIGHT, ADDITIONAL QPF
AMOUNTS. OTHERWISE, SOME RIVERS CONTINUE TO RISE OR CREST (INTO
MINOR, MODERATE, AND MAJOR FLOOD STAGES) THROUGH SATURDAY WITH
THE RAINFALL THROUGH THE WEEK, REFER TO THE .HYDROLOGY SECTION
FOR ADDITIONAL INFORMATION.
DRIER CONDITIONS ARE EXPECTED ON SATURDAY, WITH A DECENT AMOUNT
OF SUNSHINE AS WELL. CLOUDS WILL MOST LIKELY LINGER OVER CENTRAL
PUGET SOUND THROUGH THE AFTERNOON. OTHERWISE, A WEAK SYSTEM WILL
PASS BY TO THE NORTH EARLY SUNDAY, RESULTING IN LIGHT
PRECIPITATION ACROSS NORTHERN WESTERN WASHINGTON, MAINLY ALONG
THE OLYMPIC PENINSULA AND NORTH OF SNOHOMISH COUNTY.
TEMPERATURES WILL BE COOLER ON SATURDAY, WITH HIGHS IN THE UPPER
40S TO LOW 50S, WITH TEMPERATURES A FEW DEGREES WARMER SUNDAY.
LONG TERM /MONDAY THROUGH FRIDAY/
DRIER CONDITIONS ON MONDAY
WITH SOME RIDGING INFLUENCE, ALTHOUGH CLOUDS WILL CONTINUE AHEAD
OF THE NEXT FRONTAL SYSTEM. THE NEXT LOW PRESSURE SYSTEM WILL
TRACK INTO NORTHERN BRITISH COLUMBIA ON TUESDAY, WITH A
RESULTING FRONT MOVING ACROSS WESTERN WASHINGTON. LOWLAND RAIN,
HIGHER ELEVATION MOUNTAIN SNOWFALL, AND BREEZY WINDS ARE
FORECAST FOR TUESDAY. UNSETTLED CONDITIONS WILL CONTINUE
WEDNESDAY AND THURSDAY WITH TROUGHING OVER BRITISH COLUMBIA,
ALONG WITH COOLER CONDITIONS AND SNOW LEVELS CLOSER TO PASS
LEVEL. UNCERTAINTY EXISTS IN THE PATTERN BY FRIDAY, BUT THERE
ARE INDICATIONS OF GENERALLY DRIER CONDITIONS, AND SLOWLY
WARMING TEMPERATURES. JD
AVIATION
MOIST WEST TO SOUTHWEST FLOW ALOFT CONTINUES ACROSS
WESTERN WASHINGTON AS A FRONT TRAVERSES THE REGION. A WEAK
PUGET SOUND CONVERGENCE ZONE MAY LINGER INTO THIS EVENING AS
WELL. VFR HAS REBOUNDED ACROSS THE AREA ASIDE FROM THE COAST.
THIS TREND WILL ATTEMPT TO LINGER TONIGHT INTO SATURDAY BUT A
FEW POCKETS OF MVFR MAY PERSIST IN AND AROUND CONVERGENCE ZONE
ACTIVITY THIS EVENING.
KSEA...VFR CURRENTLY AS CIGS HAVE SCATTERED THIS AFTERNOON. SURFACE
WINDS SOUTHERLY 10 TO 14 KNOTS WITH GUSTS TO 20-25 KNOTS BEFORE
DIMINISHING TOWARDS 00-02Z THIS EVENING. A TRANSITION TO N/NE
SURFACE WINDS OF 8 KNOTS OR LESS IS PRESENTLY EXPECTED TO REACH THE
TERMINAL IN THE 01Z-03Z WINDOW. LOW-END VFR TO HIGH-END MVFR TONIGHT
WITH HIGH CONFIDENCE VFR DEVELOPING INTO SATURDAY.
41
MARINE
A FRONT HAS TRAVERSED ACROSS AREA WATERS THIS
AFTERNOON WITH BREEZY WINDS. GALE FORCE GUSTS ARE POSSIBLE
THROUGH THE STRAIT OF JUAN DE FUCA TONIGHT WITH THE THREAT
ENDING EARLY SATURDAY MORNING. SCAS REMAIN FOR THE COAST AND
PORTIONS OF THE INLAND WATERS BUT THE THREAT SHOULD SUBSIDE INTO
SATURDAY MORNING AS WELL. A SURFACE RIDGE WILL SLIDE EASTWARD
ACROSS THE WATERS OVER THE WEEKEND. A STRONG FRONTAL SYSTEM WILL
REACH THE WATERS MONDAY NIGHT INTO TUESDAY WITH THE POTENTIAL
FOR ADDITIONAL WIDESPREAD WIND/WAVE RELATED HEADLINES.
COASTAL SEAS ARE EXPECTED TO REMAIN GENERALLY UNDER 10 FEET INTO
MONDAY BEFORE A SUB-990 MILLIBAR LOW PASSING OVER THE OFFSHORE
WATERS GENERATES ANOTHER ROUND OF DOUBLE DIGIT SEAS.
41
HYDROLOGY
AN ACTIVE HYDROLOGIC SITUATION CONTINUES TO UNFOLD
ACROSS WESTERN WASHINGTON THIS AFTERNOON. THE FRONT IS PROGRESSING
INTO THE CASCADES WITH LINGERING SHOWERS BEHIND IT. GIVEN THE RAIN
TAPERING OFF, AREA RIVERS WILL CONTINUE TO RUN ELEVATED AS LOCAL
TRIBUTARIES AND OTHER SOURCES CONTINUE TO FEED THE MAIN STEM RIVERS.
IN GENERAL, CRESTS ARE EXPECTED TO OCCUR LATE TONIGHT INTO THE
WEEKEND. FLOOD WARNINGS WILL PERSIST UNTIL SUNDAY AND MONDAY FOR A
NUMBER OF THE FORECAST POINTS. RIVERS IN KING AND SNOHOMISH COUNTIES
IN PARTICULAR ARE RUNNING IN THE MODERATE TO MAJOR CATEGORIES. A
NUMBER OF ADDITIONAL RIVERS THROUGHOUT THE AREA ARE BETWEEN MINOR
AND MODERATE.
PRECIPITATION TAPERS OVER THE WEEKEND AND TEMPERATURES COOL OFF. THE
NEXT WEATHER SYSTEM IS FORECAST TO BRING ADDITIONAL RAIN TO THE
REGION NEXT TUESDAY AND WEDNESDAY.
21
SEW WATCHES/WARNINGS/ADVISORIES
WA...FLOOD WATCH UNTIL 5 PM PDT THIS AFTERNOON FOR CASCADES OF
SNOHOMISH AND NORTHERN KING COUNTIES-CASCADES OF SOUTHERN
KING COUNTY-CASCADES OF WHATCOM AND SKAGIT COUNTIES-CITY
OF SEATTLE-DOWNTOWN EVERETT / MARYSVILLE AREA-EASTSIDE-
FOOTHILLS AND VALLEYS OF CENTRAL KING COUNTY-FOOTHILLS
AND VALLEYS OF PIERCE AND SOUTHERN KING COUNTIES-
FOOTHILLS AND VALLEYS OF SNOHOMISH AND NORTHERN KING
COUNTIES-FOOTHILLS AND VALLEYS OF THE NORTH CASCADES-
FOOTHILLS OF THE WESTERN AND SOUTHERN OLYMPIC PENINSULA-
LOWLANDS OF PIERCE AND SOUTHERN KING COUNTIES-LOWLANDS OF
WESTERN SKAGIT AND NORTHWESTERN SNOHOMISH COUNTIES-
LOWLANDS OF WESTERN WHATCOM COUNTY-MIDDLE CHEHALIS RIVER
VALLEY-OLYMPIA AND SOUTHERN PUGET SOUND-OLYMPICS-
SHORELINE / LYNNWOOD / SOUTH EVERETT AREA-SOUTHERN HOOD
CANAL-WILLAPA AND BLACK HILLS.
PZ...SMALL CRAFT ADVISORY UNTIL 11 AM PDT SATURDAY FOR WEST
ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
GALE WARNING UNTIL 3 AM PDT SATURDAY FOR CENTRAL U.S. WATERS
STRAIT OF JUAN DE FUCA-EAST ENTRANCE U.S. WATERS STRAIT
OF JUAN DE FUCA.
SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 11 AM PDT
SATURDAY FOR ADMIRALTY INLET.
SMALL CRAFT ADVISORY UNTIL 5 PM PDT THIS AFTERNOON FOR PUGET
SOUND AND HOOD CANAL.
SMALL CRAFT ADVISORY UNTIL 5 AM PDT SATURDAY FOR COASTAL
WATERS FROM CAPE FLATTERY TO JAMES ISLAND 10 TO 60 NM-
COASTAL WATERS FROM CAPE FLATTERY TO JAMES ISLAND OUT 10
NM-COASTAL WATERS FROM JAMES ISLAND TO POINT GRENVILLE 10
TO 60 NM-COASTAL WATERS FROM JAMES ISLAND TO POINT
GRENVILLE OUT 10 NM-COASTAL WATERS FROM POINT GRENVILLE
TO CAPE SHOALWATER 10 TO 60 NM-COASTAL WATERS FROM POINT
GRENVILLE TO CAPE SHOALWATER OUT 10 NM.
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