899
FXUS66 KSEW 212214
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
314 PM PDT THU MAY 21 2026
SYNOPSIS
UPPER LEVEL RIDGE CENTERED OFFSHORE THROUGH FRIDAY WILL WEAKEN
FRIDAY NIGHT AND SATURDAY. SURFACE HIGH PRESSURE BUILDING AHEAD
OF THE NEXT WEATHER SYSTEM WITH INCREASING LOW LEVEL ONSHORE
FLOW SATURDAY NIGHT INTO SUNDAY. SYSTEM ARRIVING MEMORIAL DAY
WITH A TRAILING UPPER LEVEL TROUGH OVER THE AREA TUESDAY. WEAK
UPPER LEVEL RIDGE TRYING TO BUILD WEDNESDAY.
SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/
SATELLITE IMAGERY SHOWS A FEW SMALL BUILDUPS OVER THE CASCADES
ALONG WITH SOME HIGH CLOUDS OTHERWISE CLEAR SKIES OVER WESTERN
WASHINGTON THIS AFTERNOON. TEMPERATURES AT 3 PM/22Z WERE IN THE
MID 60S TO MID 70S.
UPPER LEVEL RIDGE CENTERED OFFSHORE REMAINING IN PLACE THROUGH
FRIDAY. LIGHT FLOW IN THE LOWER LEVELS. FRIDAY LOOKS TO BE A
REPEAT OF TODAY WITH JUST PATCHY FOG NEAR SUNRISE OTHERWISE
MOSTLY CLEAR SKIES. ONSHORE FLOW INCREASING LATE IN THE DAY
WILL PUT A CAP ON THE HIGH TEMPERATURES WITH MID 60S TO UPPER
70S IN THE FORECAST. LOWS TONIGHT IN THE 40S AND LOWER 50S.
RIDGE FLATTENS OUT FRIDAY NIGHT INTO SATURDAY. LOW LEVEL ONSHORE
FLOW REMAINING INTACT WITH THE MARINE LAYER GETTING INLAND
SATURDAY MORNING. THE LAYER WILL BE SHALLOW AND DISSIPATE IN THE
AFTERNOON. A LITTLE COOLER SATURDAY, ABOUT 5 DEGREES VERSUS
FRIDAY, WITH HIGHS IN THE 60S TO LOWER 70S. LOWS IN THE 40S.
SURFACE RIDGE OUT AHEAD OF AN APPROACHING SYSTEM BUILDING OVER
THE COASTAL WATERS INCREASING THE LOW LEVEL ONSHORE FLOW
SATURDAY NIGHT. POSSIBLE GALE FORCE WESTERLIES DOWN THE STRAIT
OF JUAN DE FUCA. INCREASING CLOUD COVER WILL KEEP LOWS A LITTLE
WARMER, IN THE MID 40S TO LOWER 50S. FELTON
LONG TERM /SUNDAY THROUGH THURSDAY/
LOW LEVEL ONSHORE FLOW SUNDAY COMBINED WITH HIGH CLOUDS OUT
AHEAD OF THE APPROACHING WEATHER SYSTEM WILL GIVE WESTERN
WASHINGTON A MOSTLY CLOUDY/PARTLY SUNNY DAY. TEMPERATURES A
LITTLE COOLER AGAIN SUNDAY WITH HIGHS MOSTLY IN THE 60S.
OPERATIONAL RUN SOLUTIONS NOW TRENDING TOWARDS THE ENSEMBLE
SOLUTIONS YESTERDAY WITH RAIN ARRIVING MEMORIAL DAY AS A FRONT
REACHES THE COAST LATE IN THE DAY. HIGHS ONLY IN THE 50S.
FRONT MOVING THROUGH MONDAY EVENING WITH COOL UPPER LEVEL TROUGH
TRAILING THE FRONT KEEPING AT LEAST A CHANCE OF SHOWERS IN THE
FORECAST TUESDAY. LOWS IN THE 40S AND HIGHS IN THE UPPER 50S TO
MID 60S.
WEAK UPPER LEVEL RIDGE MOVING INTO THE AREA WEDNESDAY FOR A DRY
FORECAST. ENSEMBLES NOT REAL CONFIDENT IN THE STRENGTH OF THE
RIDGE THURSDAY. WEAK SYSTEM RIDING BY TO THE NORTH FOR NOW
PRODUCING SLIGHT CHANCE POPS ACROSS THE AREA. HIGHS NEAR NORMAL,
MOSTLY IN THE 60S. LOWS IN THE 40S AND LOWER 50S.
AVIATION
HIGH PRESSURE OFFSHORE WILL KEEP THE WEATHER PATTERN CONSISTENT
TONIGHT INTO FRIDAY. VFR CONDITIONS WILL PREVAIL THROUGH THE TAF
PERIOD FOR MOST. THE EXCEPTION WILL BE THE PACIFIC COAST ONCE AGAIN,
WHERE STRATUS IS EXPECTED TO REDEVELOP AND BRING IFR CONDITIONS
OVERNIGHT INTO FRIDAY MORNING. THE STRATUS LOOKS TO MAKE IT SLIGHTLY
FURTHER INLAND COMPARED TO THIS MORNING, BUT STILL REMAIN SHORT OF
THE PUGET SOUND INTERIOR. PROBABILITIES HOVER AROUND 30-50% FOR
TERMINALS INCLUDING OLM, PWT, AND CLM FOR SEEING LOW CEILINGS.
CEILINGS SHOULD CLEAR QUICKLY AOA 17-19Z FRI. N/NW WINDS 5-8 KT
BECOMING LIGHT AND VARIABLE TONIGHT. WINDS RESUME TOMORROW AGAIN NW
5-10 KT.
KSEA...VFR CONDITIONS THROUGH THE PERIOD. PROBABILITY OF SEEING
STRATUS IS AROUND 25-30%, BUT CONFIDENCE IS HIGHER ON REMAINING
MOSTLY CLEAR OVERNIGHT. WINDS N/VARIABLE 5-8 KT BECOMING LIGHT
OVERNIGHT. NW WINDS 5-10 KT DURING THE DAY FRIDAY.
62
MARINE
THE PATTERN CONTINUES TO REMAIN STEADY WITH HIGH PRESSURE OFFSHORE
AND LOWER PRESSURE INLAND THROUGH THE REST OF THE WEEK AND INTO THIS
WEEKEND. NORTHWESTERLY WINDS PERSIST OVER THE COASTAL WATERS, WITH
THE OUTER-MOST AREAS UP TO 60 NM WATERS WAY EXPERIENCING WINDS UP TO
20 TO 25 KT, THUS ALLOWING FOR A SMALL CRAFT ADVISORY FROM THIS
AFTERNOON THROUGH FRIDAY MORNING. WINDS WILL EASE FRIDAY MORNING AS
THE GRADIENT DECREASES AS THE HIGH SHIFTS WESTWARD. ANOTHER ROUND OF
SMALL CRAFT WINDS IS LIKELY FRIDAY NIGHT INTO SATURDAY WITH MORE
ROBUST ONSHORE FLOW FROM THE HIGH MOVING BACK EASTWARD CLOSER TO
SHORE. WINDS LOOK TO EASE ONCE AGAIN SUNDAY. A LOW PRESSURE SYSTEM
WILL TRAVERSE THE AREA ON MONDAY, BRINGING WIDESPREAD SMALL CRAFT
CONDITIONS ACROSS MUCH OF THE AREA WATERS.
DIURNALLY DRIVEN WESTERLY PUSHES DOWN THE STRAIT OF JUAN DE FUCA
WILL OCCUR EACH AFTERNOON AND EVENING THROUGH MONDAY, WHICH WILL
ALSO BRING SMALL CRAFT CONDITIONS TO THE CENTRAL AND EASTERN STRAIT.
SATURDAY LOOK TO BE THE STRONGEST DAY, WITH A 30-50% CHANCE OF GALE
FORCE WINDS THROUGH THE STRAIT.
SEAS REMAIN 6-10 FT THROUGH THE REST OF THE WEEK AND THIS WEEKEND,
WITH THE LARGEST AND STEEPEST WAVES OVER THE OFFSHORE WATERS.
DOMINANT PERIODS WILL BE AROUND 8 SECONDS THROUGH FRIDAY, AND THEN
ONCE AGAIN ON SATURDAY AS WAVES BECOME DRIVEN MORE BY THE LOCAL
WIND. WAVES INCREASE TO 10-13 FT MONDAY INTO TUESDAY AS THE LOW
PRESSURE SYSTEM MOVES THROUGH THE AREA.
62
HYDROLOGY
THE DAILY HYDROLOGY DISCUSSION HAS ENDED UNTIL THE START OF THE
NEXT RAINY SEASON; IT WILL ONLY BE UPDATED DURING THIS TIME AS
NEEDED.
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM PDT FRIDAY FOR CENTRAL U.S.
WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE U.S. WATERS
STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY UNTIL 11 AM PDT FRIDAY 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.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page