637
FXUS66 KSEW 210331
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
831 PM PDT FRI MAR 20 2026
SYNOPSIS
POST-FRONTAL ONSHORE FLOW CONTINUES TONIGHT. 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/
POST-FRONTAL
ONSHORE FLOW CONTINUES THIS EVENING. A WEAK AREA OF CONVERGENCE
IS LOCATED ACROSS PORTIONS OF SNOHOMISH AND SKAGIT COUNTIES WITH
BREEZY 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
A ZONAL FLOW PATTERN CONTINUES WITH A STRONG JET
OVERHEAD KEEPING THE FLOW WESTERLY. THE CURRENT JET MAX WILL MOVE
EAST OF THE STATE SATURDAY. POST-COLD FRONT CONVERGENCE ZONE SHOWERS
CONTINUE IN PORTIONS OF THE INTERIOR AND THE NORTH CASCADES.
CEILINGS IN THESE AREAS HAVE DROPPED TO MVFR, BUT THE PROBABILITIES
FOR ADDITIONAL MVFR DECREASES THROUGH THE NIGHT FOR MOST AREAS
(THERE IS A LOW POTENTIAL FOR BRIEF LOW CIGS/VIS TONIGHT IN THE
SOUTH INTERIOR). VFR SKIES ARE EXPECTED FOR THE MAJORITY OF
SATURDAY. SOUTHWEST WINDS WILL TRANSITION TO THE NORTHWEST TONIGHT,
WITH GUSTS LINGERING ALONG THE STRAIT OF JUAN DE FUCA, AND THE
PACIFIC COAST.
KSEA...VFR THROUGH TONIGHT WITH A SLIGHT CHANCE OF MVFR CEILINGS IN
THE MORNING, THEN VFR FOR THE REST OF SATURDAY. SOUTHWEST WINDS
AROUND 5-10 KT THIS EVENING, THEN SWITCHING TO THE NORTHEAST AFTER
06Z, AND NORTHWEST AFTER 19Z.
HPR
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 EVENING. 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 TONIGHT INTO THE WEEKEND. FLOOD WARNINGS WILL
PERSIST THROUGH SUNDAY 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.
JD/21
SEW WATCHES/WARNINGS/ADVISORIES
WA...FLOOD WATCH THROUGH SATURDAY 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 4 AM PDT SATURDAY FOR WEST ENTRANCE
U.S. WATERS STRAIT OF JUAN DE FUCA.
GALE WARNING UNTIL 5 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 UNTIL 11 AM PDT SATURDAY FOR ADMIRALTY
INLET.
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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