534
FXUS66 KSEW 030454
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
854 PM PST TUE DEC 2 2025
SYNOPSIS
WEAK WARM FRONT WILL BRUSH THE NORTHWEST CORNER
WEDNESDAY. ANOTHER SYSTEM MOVING OVER THE TOP OF AN OFFSHORE RIDGE
MOVING THROUGH THURSDAY. A SERIES OF STRONGER AND WETTER
SYSTEMS WILL TAKE AIM AT WESTERN WASHINGTON BEGINNING FRIDAY AND
CONTINUING THROUGH THE MIDDLE OF NEXT WEEK.
SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/
WE'VE GOT A QUIET NIGHT AHEAD WITH AN UPPER RIDGE AXIS REMAINING
WELL OFFSHORE. A WEAK SYSTEM RIDING ALONG THE PERIPHERY OF IT WILL
BRING A LITTLE LIGHT PRECIP TO THE COAST AND NORTH INTERIOR
TOMORROW, BUT THE REMAINDER OF THE AREA WILL REMAIN FAIRLY DRY.
THE DAYS OF QUIET ARE NUMBERED WITH A MUCH MORE ACTIVE PERIOD
AHEAD. NO PUBLIC FORECAST UPDATES ARE ANTICIPATED. PREVIOUS
DISCUSSION FOLLOWS WITH AN UPDATED AVIATION PORTION. 27
THE SHORT TERM PATTERN IS DOMINATED BY STRONG HIGH PRESSURE
OFFSHORE, WITH MOIST NW FLOW OVER WESTERN WA. WE'RE LOOKING FOR
MAINLY DRY WEATHER TONIGHT AND WEDNESDAY (THE DRIEST DAY OVER THE
NEXT 7) ALTHOUGH THE LOW LEVEL AIR MASS WILL REMAIN MOIST FOR LOW
CLOUDS AND FOG. THE FORECAST IS WETTER HEADING INTO THURSDAY AS THE
NEXT WAVE OF MOISTURE OVERRIDES THE RIDGE AND MOVES INTO THE
REGION. THIS MOISTURE TAP IS AIMED PARTICULARLY OVER THE CENTRAL
CASCADES FOR MOUNTAIN RAIN AND HIGH ELEVATION SNOW, POTENTIALLY
SENDING A FEW RIVERS IN KING AND SNOHOMISH COUNTIES INTO ACTION
STAGE. 33
LONG TERM /FRIDAY THROUGH TUESDAY/
THE PATTERN REMAINS ACTIVE
THROUGH THE EXTENDED PERIOD AS WAVE AFTER WAVE OF MOISTURE
STREAMS THROUGH WESTERN WA. THE MAIN CONCERN WILL BE FOCUSED
TOWARD RIVER LEVELS WITH POTENTIAL THREATS OF FLOODING AS WE
HEAD THROUGH EARLY NEXT WEEK. WITHOUT MUCH OF A BREAK, THE
LANDSLIDE THREAT WILL ALSO BE ELEVATED DUE TO SATURATED SOILS
AND ANTECEDENT CONDITIONS. THE AIR MASS WILL BE MILD WITH TEMPS
IN THE 40S AND 50S, AND HIGH SNOW LEVELS. STEVENS PASS MAY SEE
PERIODS OF LIGHT SNOW WITH ALL RAIN DOWN AT SNOQUALMIE PASS.
IN ADDITION, HIGH ASTRONOMICAL TIDES WILL BE OBSERVED THROUGH
THIS SAME PERIOD WITH POTENTIAL FOR MINOR COASTAL FLOODING (BOTH
COAST AND INTERIOR). 33
AVIATION
NORTHWEST FLOW ALOFT WILL CONTINUE INTO WEDNESDAY WITH A
WARM FRONT APPROACHING THE AREA LATE IN THE PERIOD. AN OVERALL TREND
OF DETERIORATING CEILINGS IS EXPECTED TOWARD DAYBREAK WITH
WIDESPREAD LOW MVFR OR IFR ACROSS THE REGION BY AROUND 12Z. SOME
MINOR IMPROVEMENT TO LOW END VFR IS POSSIBLE ACROSS PORTIONS OF THE
INTERIOR WEDNESDAY AFTERNOON, BUT IS LIKELY TO BE BRIEF IF IT DOES
MATERIALIZE.
KSEA...A SOLID CLOUD DECK AROUND 035 HAS SLOWED LOW CLOUD FORMATION.
WILL LIKELY SCALE BACK HOW LOW CEILINGS WILL DEVELOP OVERNIGHT.
PRESENT THINKING IS MORE ALONG THE LINES OF LOW END MVFR OR
OCCASIONAL IFR. CEILINGS MAY LIFT TO VFR BRIEFLY AFTER 21Z
WEDNESDAY, BUT CONFIDENCE IN THAT OUTCOME IS LOW. SURFACE WINDS
LIGHT NORTHEASTERLY ARE EXPECTED TO BECOME LIGHT AND VARIABLE
OVERNIGHT THEN EVENTUALLY LIGHT S/SE TOWARD MORNING. 27
MARINE
SURFACE HIGH PRESSURE OFFSHORE WILL CONTINUE TO BRING
BENIGN CONDITIONS TO THE AREA WATERS THIS EVENING. WINDS AND
SEAS WILL START TO BECOME ELEVATED ON FRIDAY AS A SERIES OF
SYSTEMS WILL START TO APPROACH THE AREA WATERS, LIKELY BRINGING
SMALL CRAFT ADVISORY GUSTS TO THE COASTAL WATERS ALONG WITH A
PUSH DOWN THE STRAIT OF JUAN DE FUCA. ACTIVE WEATHER CONTINUES
THROUGHOUT THE WEEKEND AND INTO THE FIRST HALF OF NEXT WEEK WITH
ELEVATED WINDS AND SEAS.
COMBINED SEAS AROUND 8 TO 10 FEET THIS AFTERNOON LOWERING TO 4
TO 6 FEET OVERNIGHT. SEAS LOOK TO GET UP AROUND 10 FEET LATE
FRIDAY NIGHT, GENERALLY STAYING THAT WAY THROUGHOUT THE WEEKEND.
SEAS LOOK TO BUILD MORE RAPIDLY 10 TO 13 FEET BY MONDAY.
MAZURKIEWICZ
HYDROLOGY
THE SERIES OF WEATHER SYSTEMS FORECAST TO REACH
THE AREA WILL EVENTUALLY INCREASE THE THREAT OF RIVER FLOODING
IN THE COMING DAYS. WEST NORTHWESTERLY FLOW ALOFT WITH THE
SYSTEM FRIDAY PUTS THE AREA OF GREATEST PRECIPITATION IN THE
NORTH CENTRAL WASHINGTON CASCADES. SNOW LEVELS RISING OVER 6000
FEET. CURRENT FORECAST 18 HOUR PRECIPITATION AMOUNTS BETWEEN 06Z
FRIDAY AND 00Z SATURDAY HAVE AN AREA OF 2 INCH BULLSEYES
BETWEEN SNOQUALMIE PASS AND GLACIER PEAK. THIS WILL PUT PRESSURE
ON THE RIVERS FLOWING OUT OF THIS AREA INCLUDING BUT NOT
LIMITED TO THE SNOQUALMIE, SKYKOMISH, SNOHOMISH AND TOLT RIVERS.
AS THE FLOW ALOFT BECOMES MORE WEST SOUTHWESTERLY THE FLOOD
THREAT WILL SHIFT TO THE FLOOD PRONE SKOKOMISH RIVER LATER IN
THE WEEKEND.
PLENTY OF UNCERTAINTY ON HOW THE PATTERN WILL SET UP EARLY NEXT
WEEK BUT THERE IS A CHANCE FOR A WIDESPREAD RIVER FLOODING
EVENT.
THE LANDSLIDE THREAT IS MINIMAL THE NEXT FEW DAYS. THE SERIES
OF SYSTEMS WILL EVENTUALLY TAKE ITS TOLL WITH THE LANDSLIDE
THREAT INCREASING THIS WEEKEND INTO EARLY NEXT WEEK. FELTON
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 10 PM PST THIS EVENING FOR COASTAL
WATERS FROM CAPE FLATTERY TO JAMES ISLAND 10 TO 60 NM-
COASTAL WATERS FROM JAMES ISLAND TO POINT GRENVILLE 10 TO
60 NM-COASTAL WATERS FROM POINT GRENVILLE TO CAPE
SHOALWATER 10 TO 60 NM.
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