299
FXUS66 KSEW 211622
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
922 AM PDT SAT MAR 21 2026
UPDATE
A NUMBER OF RIVER FLOOD WARNINGS WERE ABLE TO BE CANCELLED THIS
MORNING AS THE RAIN ENDED AND RIVERS FELL BELOW FLOOD STAGES.
THERE ARE STILL FLOODS ONGOING ON AREA RIVERS SO BE SURE TO HEED
ROAD CLOSURE WARNINGS AND NEVER DRIVE THROUGH FLOODWATERS.
OTHERWISE, QUIETER WEATHER IS IN STORE FOR THE WEEKEND BEFORE
ACTIVITY RAMPS UP AGAIN BY THE MIDDLE OF THE NEW WEEK.
21
SYNOPSIS
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
WESTERLY FLOW ALOFT WILL PREVAIL TODAY AND AN EMBEDDED SHORTWAVE
WILL MOVE THROUGH THE AREA LATE TONIGHT INTO EARLY SUNDAY. CONDITIONS
ACROSS THE AREA TERMINALS REMAIN MOSTLY VFR, THOUGH A FEW SPOTS
ARE REPORTING MVFR CIGS WITH RADAR SHOWING SOME WEAK CONVERGENCE
SHOWERS PERSISTING ACROSS THE CENTRAL SOUND THIS MORNING. EXPECT
MOSTLY VFR CONDITIONS TO PREVAIL OUTSIDE SHOWER ACTIVITY AND
FOR MID TO UPPER LEVEL CLOUDS TO SLOWLY CLEAR THROUGHOUT THE
DAY. LOWER CEILINGS WILL BEGIN TO RETURN TONIGHT INTO EARLY
SUNDAY MORNING AS A DISSIPATING COLD FRONT ARRIVES ACROSS THE
AREA.
WINDS THIS MORNING ARE MOSTLY LIGHT WITH THE EXCEPTION BETWEEN
SEATTLE AND WHIDBEY ISLAND WHERE WESTERLY AND NORTHERLY WINDS
CONTINUE TO PUSH OUT OF THE STRAIT OF JUAN DE FUCA. WINDS WILL
GENERALLY REMAIN OUT OF THE NORTH AND WEST (THROUGH THE PUGET
SOUND) THROUGH THIS AFTERNOON, BEFORE MORE SOUTHWEST TO SOUTH
WINDS BEGIN TO PREVAIL BETWEEN AROUND 00-06Z SUN, THOUGH
GENERALLY 5 KT OR LESS BY THIS TIME.
KSEA...VFR CIGS AT THE TERMINAL THIS MORNING. BROAD POST-FRONTAL
CONVERGENCE SHOWERS LOOK TO LARGELY REMAIN NORTH OF THE TERMINAL
TODAY, THOUGH COULD SEE A BRIEF DROP IN CIGS SHOULD ONE MOVE
INTO THE VICINITY OF THE TERMINAL. CEILINGS WILL GRADUALLY
CONTINUE TO LIFT AND SCATTER BETWEEN 17-20Z. VFR CONDITIONS ARE
EXPECTED TO PREVAIL THROUGH THE REMAINDER OF THE DAY, BEFORE LOWER
CEILINGS RETURN AROUND 12Z SUN. N/NE WINDS 8-12 KT WILL BECOME
SOUTHERLY FROM 23-02Z THIS EVENING.
62/14
MARINE
WINDS WILL CONTINUE TO SUBSIDE ACROSS THE AREA, WITH THE
STRONGEST WINDS LINGERING THROUGH THE STRAIT OF JUAN DE FUCA INTO
ADMIRALTY INLET THROUGH THE MORNING HOURS. 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. THERE REMAINS
UNCERTAINTY ON THE EXACT TRACK 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 MOVE NORTHWEST WITH THE SURFACE FRONT TRAVERSING
THE COASTAL WATERS TUESDAY EVENING.
SEAS WILL PERSIST AT 6 TO 8 FT 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 11 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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