166
FXUS66 KSEW 190324
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
724 PM PST WED FEB 18 2026
SYNOPSIS
A BROAD LOW PRESSURE SYSTEM OVER THE NE PACIFIC WILL
MOVE SOUTHEASTWARD THROUGH THURSDAY, KEEPING SCATTERED RAIN AND
OVERNIGHT SNOW SHOWERS IN THE FORECAST THROUGH THEN. COOLER
TEMPERATURES FOLLOW THURSDAY AND FRIDAY WITH FRASER RIVER OUTFLOW. A
WARMER PATTERN RETURNS FRIDAY INTO EARLY NEXT WEEK, ACCOMPANIED BY A
MORE SIGNIFICANT SYSTEM BRINGING GUSTY WINDS, AS WELL AS ADDITIONAL
RAIN AND MOUNTAIN SNOW.
SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/
NO MAJOR CHANGES HAVE BEEN MADE TO THE FORECAST THIS EVENING.
SHOWERS ARE MOVING NORTH THROUGH PUGET SOUND AND PORTIONS OF THE
COAST AS THE LOW SAUNTERS OFF TO THE SOUTHEAST. THE REST OF THE
PREVIOUS DISCUSSION CAN BE FOUND BELOW, WITH AN UPDATE TO THE
AVIATION SECTIONS.
THIS SYSTEM WILL CONTINUE TO TRACK TO THE SOUTHEAST TONIGHT
INTO THURSDAY, AND BRING THE SHOWERS WITH IT. ACROSS THE
NORTHERN HALF OF THE AREA, SHOWERS WILL BEGIN TO TAPER OFF
TONIGHT, THROUGH SOME OFFSHORE FLOW COULD ENHANCE SHOWER
ACTIVITY ON THE WESTERN SLOPES OFF THE STRAIT OF JUAN DE FUCA
FOR A BIT THIS EVENING, WHICH COULD CAUSE SOME LIGHT ACCUMULATIONS
THERE AND ALONG US-101. THE MAIN BULK OF THE ACTIVITY TONIGHT
WILL BE ACROSS SOUTHWEST WASHINGTON. TOMORROW SHOULD BE MOSTLY
DRY ACROSS THE LOWLANDS, WITH THE BEST CHANCES FOR ADDITIONAL
SHOWERS STAYING OVER THE CASCADES. ON FRIDAY, AS SYSTEMS START
TO DEVELOP OVER THE NE PACIFIC, THAT MAY SEND SOME MOISTURE UP
OUR WAY TO GET SOME CHANCES FOR RAIN ON THE COAST.
TEMPERATURES WILL BE BELOW NORMAL ACROSS THE AREA THROUGH FRIDAY,
BUT FRASER RIVER OUTFLOW WINDS WILL HELP TO KEEP THE NORTH INTERIOR
COOLER. LOWS TONIGHT IN THE LOW 30S TO MID 20S.
LOWER 20S POSSIBLE IN WHATCOM COUNTY, AS WELL AS WIND CHILLS IN THE
TEENS BY EARLY THURSDAY MORNING. LOWS THURSDAY NIGHT/FRIDAY MORNING
SLIGHTLY COOLER, IN THE MID TO LOW 20S. HIGH TEMPERATURES EACH DAY
WILL BE IN THE MID TO LOWER 40S, EXCEPT UPPER 30S ON THURSDAY IN THE
NORTHERN INTERIOR AND STRAIT.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
THIS WEEKEND AND EARLY NEXT WEEK WILL SIGNAL A WARMER BUT MORE
ACTIVE PATTERN AS A LARGE UPPER LEVEL TROUGH DIGS OVER THE NE
PACIFIC. WITH SEVERAL SHORTWAVES MOVING THROUGH IT, THESE WILL WILL
GENERATE SEVERAL STRONGER BUT FAST-MOVING LOW PRESSURE SYSTEMS THAT
WILL SWEEP ALONG THE WASHINGTON COAST. THESE SYSTEMS WILL PUSH SNOW
LEVELS UP TO AROUND 2000-3000 FT. WHILE QPF AND SNOW AMOUNTS DON'T
LOOK TO BE NOTEWORTHY AT THIS POINT, THESE WILL BE WINDIER SYSTEMS
WITH MORE WIDESPREAD BREEZY TO GUSTY CONDITIONS. A FEW INCHES OF
SNOW WILL BE POSSIBLE AT THE PASSES WILL BE POSSIBLE EACH DAY.
TEMPERATURES WILL WARM WITH HIGHS GOING UP INTO THE MID TO UPPER 40S
FRIDAY AND SATURDAY, REACHING THE LOW 50S SUNDAY AND ONWARD. LOWS
RETURN TO THE MID TO UPPER 30S.
62
AVIATION
WESTERLY TO SOUTHWESTERLY FLOW ALOFT CONTINUES AS LOW PRESSURE
MOVES SOUTH OF THE AREA. SURFACE FLOW ACROSS THE TERMINALS WILL
BEGIN TO SHIFT NORTHERLY OVERNIGHT WITH COOL AIR LINGERING.
EXPECT MVFR TO VFR CIGS ACROSS THE AREA TONIGHT AS SHOWERS BEGIN
TO TAPER OFF. GUSTIER CONDITIONS WILL BE PRESENT OVERNIGHT AT
KBLI AS FRASER OUTFLOW CONTINUES, KEEPING THE NORTHERN AREAS
GENERALLY DRIER. IFR CIGS POSSIBLE IN SOUTH PUGET SOUND AND IN
THROUGH THE CHEHALIS VALLEY.
KSEA...MVFR CIGS AND RAIN SHOWERS NOW AT THE TERMINAL, LIKELY TO
END IN THE NEXT HOUR OR TWO. GUIDANCE IS INDICATIVE OF MVFR
CIGS LINGERING THROUGHOUT THE NIGHT, BECOMING VFR TOMORROW
AFTERNOON. WINDS ARE EXPECTED TO BECOME ENE BY 06Z, BECOMING
MORE NORTHERLY EARLY TOMORROW MORNING. SPEEDS WILL BE BETWEEN
7-9 KTS AFTER 14Z.
21
MARINE
A SURFACE TROUGH OVER THE WASHINGTON COASTAL AREAS WILL SHIFT
SOUTHWARD TONIGHT INTO THE OREGON WATERS. A SURFACE RIDGE WILL
STRENGTHEN TONIGHT OVER THE INTERIOR OF BRITISH COLUMBIA FOR A BRIEF
INCREASE IN FRASER RIVER OUTFLOW AND EASTERLY FLOW THROUGH THE
STRAIT. SMALL CRAFT ADVISORIES HAVE BEEN ISSUED FOR THE STRAIT AND
ADJACENT WATERS OF THE NORTH INTERIOR. LIGHT OFFSHORE FLOW WILL
CONTINUE INTO FRIDAY WITH A BROAD SURFACE TROUGH IN PLACE ACROSS THE
COASTAL AND OFFSHORE WATERS AND A WEAK RIDGE EAST OF THE CASCADES.
LOW PRESSURE AT THE SURFACE AND ALOFT WILL DEEPEN OFFSHORE OVER THE
WEEKEND FOR INCREASING OFFSHORE FLOW AND LIKELY WIND RELATED
HEADLINES FOR THE COASTAL WATERS, STRAIT ENTRANCES, AND NORTHERN
INLAND WATERS. THIS PATTERN WILL PERSIST INTO EARLY NEXT WEEK.
COASTAL SEAS ARE EXPECTED TO REMAIN BELOW 10 FEET INTO THURSDAY, BUT
INCREASED ACTIVITY OFFSHORE THIS WEEKEND AND BEYOND WILL DRIVE SEAS
BACK INTO HAZARDOUS DOUBLE DIGITS ONCE AGAIN AS ADDITIONAL LARGE
SWELL TRAINS ARRIVE.
27
HYDROLOGY
NO RIVER FLOODING IS EXPECTED OVER THE NEXT SEVEN DAYS.
SEW WATCHES/WARNINGS/ADVISORIES
WA...COLD WEATHER ADVISORY UNTIL NOON PST THURSDAY FOR LOWLANDS OF
WESTERN WHATCOM COUNTY-SAN JUAN COUNTY.
COLD WEATHER ADVISORY FROM 1 AM TO 10 AM PST THURSDAY FOR
EASTERN STRAIT OF JUAN DE FUCA-ISLAND COUNTY-LAKE
CRESCENT AREA INCLUDING US 101-PORT TOWNSEND AREA-WESTERN
STRAIT OF JUAN DE FUCA.
PZ...SMALL CRAFT ADVISORY UNTIL 10 AM PST THURSDAY FOR EAST
ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA-WEST ENTRANCE
U.S. WATERS STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY UNTIL 10 AM PST THURSDAY FOR CENTRAL U.S.
WATERS STRAIT OF JUAN DE FUCA-NORTHERN INLAND WATERS
INCLUDING THE SAN JUAN ISLANDS.
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