213
FXUS66 KSEW 210942
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
242 AM PDT SAT MAR 21 2026
SYNOPSIS
DRIER AND SLIGHTLY COOLER WEATHER WILL PREVAIL ACROSS WESTERN
WASHINGTON THIS WEEKEND INTO MONDAY WITH HIGH PRESSURE. A
DISSIPATING SYSTEM WILL ARRIVE SATURDAY NIGHT INTO EARLY
SUNDAY, BRINGING CHANCES FOR LIGHT RAIN TO THE NORTHWESTERN
AREAS. A STRONGER LOW PRESSURE SYSTEM WILL BRING RAIN, HIGHER-
ELEVATION MOUNTAIN SNOW, AND GUSTY WINDS ACROSS THE AREA TUESDAY
INTO WEDNESDAY.
SHORT TERM /TODAY THROUGH MONDAY/
TODAY WILL MARK THE START OF A MORE BENIGN AND DRIER WEATHER
PERIOD AS THE FRONT THAT CARRIED THE ATMOSPHERIC RIVER CONTINUES
TO MOVE INLAND. THE UPPER LEVEL PATTERN REMAINS MOSTLY ZONAL,
WITH THE EXCEPTION OF A BRIEF SHORTWAVE THAT MOVES ACROSS THE
AREA LATE SATURDAY INTO EARLY SUNDAY. THAT WILL SEND A WEAK
FRONTAL SYSTEM ACROSS THE AREA THAT TIME THAT WILL BRING CHANCES
FOR LIGHT SHOWERS, MAINLY ALONG THE OLYMPIC PENINSULA AND THE
NORTHERN PORTIONS OF THE INTERIOR SATURDAY NIGHT INTO EARLY
SUNDAY. AREAS EVERETT AND SOUTHWARD WILL REMAIN MOSTLY DRY AS
THE FRONT DISSIPATES QUICKLY AS IT MOVES ONSHORE.
TEMPERATURES WILL BE A TOUCH COOLER THAN THEY HAVE BEEN PREVIOUSLY,
WITH HIGHS TODAY IN THE UPPER 40S TO LOW 50S. LOWS TONIGHT IN THE
LOW TO MID 30S. SUNDAY AND MONDAY WILL BE SLIGHTLY WARMER, WITH
HIGHS IN THE LOW TO MID 50S.
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
ACTIVE WEATHER WILL BEGIN TO RETURN ON TUESDAY AS A SHORTWAVE
TROUGH DEVELOPS OVER THE NORTHEAST PACIFIC AND MOVES
NORTHWESTWARD INTO BRITISH COLUMBIA. THIS WILL ALLOW FOR A
STRONG LOW PRESSURE SYSTEM TO DEVELOP OVER THE NORTHEAST PACIFIC
AND THEN PUSH NORTHWESTWARD INTO THE PACIFIC NORTHWEST. MODELS
DIFFER ON THE EXACT TRACK OF THIS LOW--WHETHER THE CENTER WILL
TRACK CLOSER TO VANCOUVER ISLAND OR WHETHER IT WILL DRIFT
FARTHER NORTH TOWARDS HAIDA GWAII--BUT A WETTER, WINDER SYSTEM
WILL BE ON TRACK TO IMPACT THE AREA TUESDAY INTO EARLY
WEDNESDAY. SINCE IT WILL BE FAST MOVING, IT WILL NOT BE A
HYDROLOGICALLY SIGNIFICANT SYSTEM WITH 0.5-1" EXPECTED ACROSS
MUCH OF THE AREA. SOUTHWESTERLY WINDS WILL INCREASE ACROSS THE
AREA TUESDAY, PEAKING TUESDAY EVENING, BEFORE DECREASING LATER
ON WEDNESDAY. THERE IS A 50- 65% FOR GUSTS TO EXCEED 45 MPH FOR
PORTIONS OF THE PACIFIC COAST AND THE NORTH INTERIOR NORTH OF
ISLAND/SKAGIT CO.S. SNOW LEVELS ABOVE 4000 FT WILL LIKELY MEAN
THAT THE SYSTEM WILL BE MOSTLY RAINFALL IN THE PASSES ON
TUESDAY. SNOW LEVELS WILL LOWER LATE TUESDAY BUT AS
PRECIPITATION DECREASES SNOW ACCUMULATIONS AT THE PASSES WILL BE
LIMITED BUT NON-ZERO THROUGH WEDNESDAY. THE ACTIVE PATTERN
LOOKS TO CONTINUE INTO THE LATE WEEK TIMEFRAME WITH ADDITIONAL,
ALBEIT WEAKER, SYSTEMS MOVING THROUGH THE AREA. TEMPERATURES
WILL LARGELY BE CONSISTENT DURING THE LONG TERM PERIOD, WITH
HIGH TEMPERATURES IN THE LOW TO MID 50S AND LOW TEMPERATURES IN
THE LOW TO MID 30S.
62
AVIATION
WEST FLOW ALOFT WILL PREVAIL WITH MOSTLY ZONAL FLOW AND
AN EMBEDDED SHORTWAVE MOVING THROUGH LATE TONIGHT. MVFR CIGS PREVAIL
ACROSS MUCH OF THE CENTRAL PUGET SOUND TERMINALS WITH WEAK BUT BROAD
POST-FRONTAL CONVERGENCE IS KEEPING CEILINGS LOWER. ELSEWHERE, VFR
CONDITIONS PREVAIL WITH MID TO UPPER LEVEL CLOUDS SLOWLY CLEARING.
CLOUDS OVER THE PUGET SOUND WILL PERSIST THROUGH MUCH OF THE MORNING
BUT SLOWLY BEGIN TO CLEAR THROUGH THE AFTERNOON WITH CEILINGS
LIFTING TO VFR ACROSS THE ENTIRE AREA. LOWER CEILINGS WILL BEGIN TO
RETURN TONIGHT INTO EARLY SUNDAY MORNING AS A DISSIPATING COLD FRONT
ARRIVES ACROSS THE AREA.
WINDS THIS MORNING MOSTLY LIGHT WITH THE EXCEPTION BETWEEN SEATTLE
AND WHIDBEY ISLAND WHERE WEST TO NORTH WINDS CONTINUE TO PUSH OUT OF
THE STRAIT OF JUAN DE FUCA. WINDS WILL GENERALLY REMAIN WEST (OR
NORTH THROUGH THE PUGET SOUND) THROUGH THIS AFTERNOON, WHEN MORE
SOUTHWEST TO SOUTH WINDS BEGIN TO PREVAIL BETWEEN AROUND 00-06Z SUN,
THOUGH GENERALLY 5 KT OR LESS BY THIS TIME.
KSEA...MVFR CIGS THIS MORNING UNDER BROAD POST-FRONTAL CONVERGENCE.
CEILINGS WILL GRADUALLY LIFT AND SCATTER THROUGH THE MORNING, AROUND
17-20Z. VFR CONDITIONS PREVAIL THROUGH THE REMAINDER OF THE TAF
PERIOD. LOWER CEILINGS RETURN AFTER 12Z SUN. N/NE WINDS 8-12 KT WILL
BECOME SOUTHERLY FROM 23-02Z THIS EVENING.
62
MARINE
WINDS WILL CONTINUE TO SUBSIDE ACROSS THE AREA, WITH THE
STRONGEST WINDS LINGERING THROUGH THE STRAIT OF JUAN DE FUCA INTO
ADMIRALTY INLET. THESE WINDS WILL EASE LATER THIS MORNING BELOW
THRESHOLDS. RATHER TRANQUIL CONDITIONS WILL PREVAIL OVER THE
WATERS FOR MUCH OF TODAY. A WEAKENING SURFACE FRONT WILL
APPROACH THE NORTHWESTERN WATERS TONIGHT AND MAY BRIEFLY
INCREASE WINDS TO NEAR SMALL CRAFT ADVISORY THRESHOLDS (40-50%
PROBABILITY BETWEEN AROUND 6PM - MIDNIGHT SUNDAY). THE FRONT
WILL DISSIPATE AS IT MOVES ACROSS THE AREA EARLY SUNDAY MORNING,
WITH HIGH PRESSURE FILLING IN ITS PLACE. THIS WILL REMAIN IN
PLACE UNTIL TUESDAY WHEN A STRONGER LOW PRESSURE IS EXPECTED TO
MOVE INTO THE REGION. THESE REMAINS UNCERTAINTY ON THE EXACT OF
THIS SYSTEM, WITH THE LEVEL OF IMPACTS DIFFERING WHETHER THE LOW
CENTER HUGS CLOSER TOWARDS VANCOUVER ISLAND OR IF TO MOVES
FARTHER NORTH TOWARDS HAIDA GWAII, BUT EXPECT STRONGER WINDS AND
SEAS WITH THIS SYSTEM. THE MOST LIKELY SOLUTION HAS WINDS
REACHING GALE FORCE ACROSS THE COASTAL WATERS WITH SEAS REACHING
INTO THE 15-18 FT RANGE. THE GEFS SHOWS A 30-50% CHANCE OF SEAS
EXCEEDING 18 FT ACROSS THE NORTHWESTERN PORTIONS OF THE COASTAL
WATERS BY EARLY WEDNESDAY. THE SYSTEM WILL NORTHWEST WITH THE
SURFACE FRONT TRAVERSING THE COASTAL WATERS TUESDAY EVENING.
SEAS TODAY AROUND 6 TO 8 FT WILL REMAIN LIKE SO THROUGH THE WEEKEND
AND INTO EARLY MONDAY UNTIL SEAS RISE WITH THE AFOREMENTIONED SYSTEM
TUESDAY INTO WEDNESDAY, LIKELY ABOVE 15 FT.
62
HYDROLOGY
ACTIVE WARNINGS ARE IN EFFECT AND RIVERS WILL
EITHER CREST OR CONTINUE TO RECEDE TODAY. ADDITIONAL FLOODING IS
NOT ANTICIPATED ON RIVERS NOT ALREADY WARNED AND THEREFORE THE
FLOOD WATCH HAS ENDED. RIVERS WILL CONTINUE TO RECEDE THROUGH
MONDAY. A WETTER SYSTEM WILL BRING SMALL RISES TUESDAY AND
WEDNESDAY BUT ADDITIONAL FLOODING IS NOT FORECAST AS THIS TIME.
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 7 AM PDT THIS MORNING FOR ADMIRALTY
INLET-CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-EAST
ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
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