610
FXUS66 KSEW 120312
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
810 PM PDT SAT APR 11 2026
SYNOPSIS
UPPER LEVEL LOW OFF THE NORTHERN CALIFORNIA COAST WILL SLOWLY MOVE
INLAND TONIGHT AND WEAKEN THROUGHOUT SUNDAY. MOISTURE AROUND THE LOW
WILL REMAIN SOUTH OF WESTERN WASHINGTON. PUGET SOUND CONVERGENCE
ZONE MONDAY OVER CENTRAL PUGET SOUND DRIFTING NORTH DURING THE
AFTERNOON AND EVENING. THE NEXT SYSTEM WILL BRING ADDITIONAL
RAINFALL TUESDAY BEFORE THE MAIN FRONT MOVES THROUGH TUESDAY NIGHT,
BRINGING BREEZY CONDITIONS PLUS POSSIBLE HEAVY MOUNTAIN SNOW. UPPER
LEVEL LOW OVER WESTERN WASHINGTON WEDNESDAY. DRYING NORTHERLY FLOW
ALOFT DEVELOPING THURSDAY.
SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/
LATEST SATELLITE IMAGERY SHOWS CLOUDS REMAINING OVER MUCH OF W WA
THIS EVENING WHILE CURRENT RADAR SHOWS MOST OF THE SHOWER ACTIVITY
HAS TAPERED OFF. A NARROW, DISSIPATING BAND OF SHOWERS IS STILL
PRESENT OVER PORTIONS OF THE STRAIT, THE SOUTHERN TIP OF VANCOUVER
ISLAND AND ALONG THE CANADIAN BORDER IN FAR NORTHERN WHATCOM COUNTY.
ALL OTHER REMAINING ACTIVITY LINGERS SOUTH OF THE AREA IN OR, WHERE
ECHOES APPEAR TO BE HAVING A HARD TIME MAKING ANY NORTHWARD
PROGRESS. THIS FITS WELL WITH LATEST MODEL DATA SHOWING THE UPPER
LOW THIS ACTIVITY IS ASSOCIATED WITH MOVING INTO NORTHERN CA AND ANY
SHOWERS LINKED TO IT REMAINING WELL SOUTH OF THE AREA.
INHERITED FORECAST REMAINS ON TRACK WITH NO EVENING UPDATE PLANNED.
FOR FURTHER FORECAST DETAILS, PLEASE REFER TO THE PREVIOUS
DISCUSSION SECTION BELOW. 18
FROM PREVIOUS DISCUSSION...SATELLITE IMAGERY SHOWS UPPER LEVEL LOW
STILL SPINNING OFF THE NORTHERN CALIFORNIA COAST. BANDS OF MOISTURE
ROTATING AROUND THE LOW WITH THE LATEST ONE JUST REACHING THE
CENTRAL PUGET SOUND AT 3 PM/22Z. PREVIOUS MOISTURE BAND BRINGING
RAIN BETWEEN BELLINGHAM AND FORKS. REST OF THE MOISTURE SPINNING
AROUND LOW SOUTH OF THE AREA. WITH ALL THE CLOUD COVER TEMPERATURES
WERE ONLY IN THE UPPER 40S TO MID 50S.
UPPER LEVEL LOW SLOWLY MOVING EAST TONIGHT INTO SUNDAY. CURRENT
BANDS OF MOISTURE OVER WESTERN WASHINGTON ROTATING OUT OF THE
AREA TONIGHT. AS THE LOW MOVES EAST THE FLOW ALOFT WILL BEGIN
TO CUT OFF THE MOISTURE FROM GETTING AS FAR NORTH AS WESTERN
WASHINGTON. AIR MASS WILL BE SLIGHTLY UNSTABLE WITH WEAK
TROUGHINESS OVER THE AREA KEEPING A CHANCE OR SLIGHT CHANCE OF
SHOWERS IN THE FORECAST SUNDAY INTO SUNDAY NIGHT. WITH PLENTY OF
CLOUD COVER LOWS TONIGHT STAYING IN THE 40S. A LITTLE LESS
CLOUD COVER SUNDAY WARMING HIGHS INTO THE MID 50S TO LOWER 60S.
LOW WEAKENING INTO AN UPPER LEVEL TROUGH SUNDAY NIGHT WITH THE
FLOW ALOFT OVER WESTERN WASHINGTON TURNING NORTHWESTERLY. AIR
MASS STILL SLIGHTLY UNSTABLE FOR A CONTINUING CHANCE OF SHOWERS.
LOWS ONCE AGAIN IN THE 40S.
WEST NORTHWESTERLY FLOW ALOFT MONDAY WITH THE LOW LEVEL FLOW
GOING ONSHORE. PUGET SOUND CONVERGENCE ZONE DEVELOPING IN THE
MORNING OVER THE CENTRAL PUGET SOUND WITH THE CONVERGENCE ZONE
CONTINUING INTO THE AFTERNOON HOURS. OUTSIDE OF THE CONVERGENCE
ZONE SHOWER ACTIVITY DRYING UP. AT LEAST MOSTLY CLOUDY SKIES
WITH THE ONSHORE FLOW WILL KEEP HIGHS IN THE MID 50S.
CONVERGENCE ZONE DISSIPATING MONDAY NIGHT. RAIN OUT AHEAD OF
THE NEXT FRONTAL SYSTEM STILL MOSTLY TO THE WEST. WARM FRONT
COULD NICK THE NORTH COAST. LOWS IN THE 40S. FELTON
LONG TERM /TUESDAY THROUGH SATURDAY/
EXTENDED MODELS IN GOOD AGREEMENT WITH A STRONG FOR APRIL FRONT
MOVING THROUGH WESTERN WASHINGTON TUESDAY NIGHT. RAIN OUT AHEAD
OF THE FRONT SPREADING OVER THE AREA DURING THE DAY. WINDS
PICKING UP IN THE AFTERNOON WITH BREEZY/WINDY CONDITIONS TUESDAY
NIGHT. NOT EXPECTING RECORD LOW MAXIMUM TEMPERATURES DUE TO THE
SHORT COLD SPELL IN 2022. HIGHS ONLY NEAR 50. SNOW LEVELS
DROPPING TO NEAR 3000 FEET WITH HEAVY SNOW IN THE MOUNTAINS
POSSIBLE TUESDAY NIGHT.
COOL UPPER LEVEL LOW DROPPING DOWN OVER WESTERN WASHINGTON
WEDNESDAY AND WEDNESDAY NIGHT. AIR MASS UNSTABLE ENOUGH TO
INCLUDE A CHANCE OF THUNDERSTORMS ALONG WITH THE SHOWERS. HIGHS
REMAINING NEAR 50.
UPPER LEVEL LOW KICKING OUT OF THE AREA WITH DRYING NORTHERLY
FLOW ALOFT DEVELOPING THURSDAY. WEAK UPPER LEVEL RIDGE TRYING
TO BUILD OVER THE AREA THURSDAY NIGHT INTO SATURDAY. HIGHS IN
THE MID 50S THURSDAY WARMING TO THE MID 50S TO LOWER 60S
SATURDAY.
WEDNESDAY AND ESPECIALLY THURSDAY MORNING ON THE COOL SIDE WITH
FROST ADVISORIES FOR THE COLDER LOCATIONS LIKE THE SOUTHWEST
INTERIOR POSSIBLE BOTH MORNINGS. LOWS WARMING SLIGHTLY FRIDAY
AND SATURDAY MORNING.
AVIATION
SOUTHERLY WINDS ALOFT BECOMING VARIABLE TO NORTHERLY LATE OVERNIGHT
INTO SUNDAY. ALL TERMINALS ARE BETWEEN MVFR AND VFR THIS EVENING,
WITH FURTHER REDUCTIONS EXPECTED OVERNIGHT INTO SUNDAY MORNING. SOME
FOG DEVELOPMENT CANNOT BE RULED OUT IN THE SW INTERIOR AND ALONG THE
COAST. OTHERWISE, LOW STRATUS IS LIKELY TO IMPACT OTHER TERMINALS IN
THE PUGET SOUND REGION THROUGH TOMORROW MORNING AND CAUSE IFR AND
LIFR CIGS. A RETURN TO VFR IS IN THE CARDS ON SUNDAY AFTERNOON AS
CEILINGS LIFT AND WSW FLOW RESUMES.
KSEA... MVFR CONDITIONS HAVE CONTINUED THIS EVENING, WITH WINDS
BEGINNING TO TURN WNW. SPEEDS ARE LIGHT, GENERALLY 5 KTS OR LESS.
THIS WILL CONTINUE THROUGH MUCH OF THE VALID TAF PERIOD. LOW
CEILINGS ARE FAVORED TO REDEVELOP TONIGHT GENERALLY AFTER 09Z, AS A
THE NBM SUGGESTS A 70% CHANCE OF MVFR CIGS DEVELOPING BY 12Z AND A
NEAR 40% CHANCE OF LIFR CONDITIONS SETTING IN AROUND THE SAME TIME.
THIS WILL MOST LIKELY BE LOW STRATUS CLOUDS AND NOT FOG. A RETURN TO
VFR LIKELY BY 20Z SUNDAY.
MCMILLIAN/21
MARINE
SURFACE LOW PRESSURE WILL MOVE SOUTH OF THE COASTAL WATERS THIS
EVENING. SEAS ARE TO REMAIN BENIGN TONIGHT BUT A SCA HAS BEEN ISSUED
STARTING SUNDAY EVENING FOR THE CENTRAL/EASTERN STRAIT AS WESTERLY
WIND FORECASTS HAVE INCREASED IN THE LATEST UPDATE. A STRONGER
FRONTAL SYSTEM ARRIVING TUESDAY INTO WEDNESDAY WILL LIKELY YIELD
MORE WIDESPREAD HEADLINES WITH ENHANCED WINDS AND SEAS.
COASTAL SEAS 4 TO 6 FEET THROUGHOUT THE WEEKEND. SEAS WILL THEN
START TO BUILD UPWARDS TO 8 TO 10 FEET BY TUESDAY EVENING AND
REMAINING ELEVATED THROUGH THURSDAY.
MCMILLIAN
HYDROLOGY
NO RIVER FLOODING THE NEXT 7 DAYS.
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 5 PM SUNDAY TO 11 AM PDT MONDAY FOR
CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE
U.S. WATERS STRAIT OF JUAN DE FUCA.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page