948
FXUS66 KSEW 161020
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
320 AM PDT TUE JUN 16 2026
SYNOPSIS
INCREASING LOW LEVEL ONSHORE FLOW WILL BRING COOLER AIR INTO
WESTERN WASHINGTON TODAY WITH HIGHS 10 TO 20 DEGREES COOLER.
UPPER LEVEL RIDGE CENTERED WELL OFFSHORE WITH NORTHWESTERLY FLOW
ALOFT AND LIGHT OR LOW LEVEL ONSHORE FLOW WILL KEEP
TEMPERATURES A FEW DEGREES ABOVE NORMAL ALONG WITH DRY
CONDITIONS THROUGH THE WEEKEND. UPPER LEVEL RIDGE BUILDING EARLY
NEXT WEEK PRODUCING SLIGHTLY WARMER TEMPERATURES.
SHORT TERM /TODAY THROUGH THURSDAY/
SATELLITE IMAGERY SHOWS STRATUS FILLING IN ALONG THE COAST WITH
SOME MIDDLE LEVEL CLOUDS OVER THE NORTHWEST INTERIOR. MOSTLY
CLEAR SKIES ELSEWHERE. TEMPERATURES AT 3 AM/10Z WERE IN THE MID
50S TO MID 60S.
MUCH COOLER TODAY WITH LOW LEVEL ONSHORE FLOW INCREASING.
STRATUS ALONG THE COAST NOT GETTING VERY FAR INLAND. WEAK LOW
LEVEL CONVERGENCE COULD PRODUCE SOME CLOUD COVER OVER THE
CENTRAL PUGET SOUND THIS AFTERNOON. MARINE AIR FILLING UP THE INTERIOR
THIS MORNING WITH HIGH TEMPERATURES DROPPING INTO THE 70S FOR
THE INTERIOR AND 60S FOR THE COAST.
LITTLE CHANGE IN THE PATTERN TONIGHT THROUGH WEDNESDAY NIGHT.
UPPER LEVEL RIDGE CENTERED WELL OFFSHORE WITH NORTHWESTERLY FLOW
ALOFT. IN THE LOWER LEVELS ONSHORE FLOW WILL WEAKEN TONIGHT
THROUGH WEDNESDAY NIGHT. LOWS IN THE UPPER 40S TO MID 50S. HIGHS
IN THE 60S ON THE COAST AND UPPER 60S TO MID 70S INLAND.
NORTHWESTERLY FLOW ALOFT CONTINUING THURSDAY WITH THE LOW LEVEL
FLOW GOING LIGHT. THIS WILL GIVE THE AREA A LITTLE WARMER DAY
WITH HIGHS IN THE UPPER 60S TO MID 70S COAST AND 70S AND LOWER
80S INLAND. FELTON
LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
UPPER LEVEL RIDGE REMAINING WELL OFFSHORE WITH NORTHWESTERLY
FLOW ALOFT THROUGH THE WEEKEND. WEAK SYSTEM MOVING BY TO THE
NORTH SUNDAY COULD PRODUCE A SHOWER IN THE NORTH CASCADES.
LIGHT LOW LEVEL FLOW BECOMING ONSHORE AT TIMES. WITH THE LACK
OF OFFSHORE FLOW TEMPERATURES WILL NOT GET TOO WARM. HIGHS
FRIDAY IN THE MID 70S TO LOWER 80S FOR THE INTERIOR COOLING TO
THE 78S OVER THE WEEKEND WITH A LITTLE MORE ONSHORE FLOW. HIGHS
ON THE COAST IN THE MID 60S TO LOWER 70S. UPPER LEVEL RIDGE
BUILDING OVER THE AREA MONDAY WITH LOW LEVEL FLOW GOING LIGHT. HIGH
TEMPERATURES WARMING INTO THE MID 70S TO MID 80S INTERIOR AND
LOWER TO MID 70S COAST. LOWS THROUGH THE PERIOD IN THE 50S.
AVIATION
AS THE UPPER LEVEL RIDGE CONTINUES TO FLATTEN, PREVAILING
WEST/NORTHWEST WINDS PERSIST. GUSTY WESTERLY WINDS ARE EXPECTED
TODAY NEAR THE COAST AS WELL AS IN AND ADJACENT TO THE STRAIT
OF JUAN DE FUCA. INFRARED SATELLITE IMAGERY SHOWS AN AREA OF
STRATUS LOCATED OFFSHORE. THESE CLOUDS ARE EXPECTED TO CREEP
CLOSER TO THE COAST AND INDUCE A PERIOD OF MVFR CEILINGS LATER
THIS MORNING. ADDITIONAL CLOUDS DEVELOP THIS AFTERNOON/EVENING
AND COULD BRING A FEW HOURS OF LOW-END VFR CEILINGS TO THE
GREATER SEATTLE METRO AREA.
KSEA...VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD. AS
ONSHORE FLOW CONTINUES TODAY, A PUGET SOUND CONVERGENCE ZONE
MAY BRIEFLY MATERIALIZE THIS MORNING AND EARLY AFTERNOON, WITH
SOUTHWESTERLY FLOW AT SEATAC FROM 18-22Z. SCATTERED TO BROKEN
CEILINGS AS LOW AS 3000FT COULD OCCUR AS CLOUDS DEVELOP THIS
AFTERNOON. AFTER 22Z, NORTHERLY FLOW WILL DOMINATE INTO THE
OVERNIGHT HOURS, ALLOWING FOR CLOUDS TO CLEAR OUT.
MARINE
ONSHORE FLOW CONTINUES TODAY AS THE SURFACE THERMAL TROUGH MOVES
EAST OF THE CASCADES INTO EASTERN WASHINGTON. NORTHWESTERLY
WINDS WILL GUST TO 25KTS OVER THE COASTAL WATERS, WITH A SMALL
CRAFT ADVISORY IN EFFECT FROM THIS AFTERNOON THROUGH EARLY
THURSDAY MORNING. SEAS WILL BECOME LOCALLY-WIND DRIVEN AND
BECOME VERY STEEP. WAVE HEIGHTS WILL INCREASE THROUGHOUT THE DAY
TUESDAY UP TO 10 TO 13 FT WITH A DOMINANT PERIOD OF AROUND 10
SECONDS. WAVES IN THE OUTERMOST WATERS MAY REACH UP TO 15 FT BY
LATE WEEK.
A GALE WARNING IS IN EFFECT FOR THE CENTRAL AND EASTERN WATERS
OF THE STRAIT OF JUAN DE FUCA, WITH GUSTS UP TO 40 KTS EXPECTED
TODAY ASSOCIATED WITH A STRONG MARINE PUSH. SMALL CRAFT
ADVISORY WINDS WILL ALSO FUNNEL DOWN INTO ADMIRALTY INLET BY
THIS AFTERNOON. WINDS EASE BY LATE TONIGHT.
FIRE WEATHER
THE RETURN OF LOW LEVEL ONSHORE FLOW TODAY WILL EASE FIRE
WEATHER CONCERNS WEST OF THE CASCADES. ELEVATED FIRE WEATHER
CONCERNS RETURN ON THE WARMER DAYS, FRIDAY AND MONDAY, DURING
THE NEXT WEEK. MINIMUM RELATIVE HUMIDITY VALUES DROPPING TO
AROUND 30 PERCENT THOSE DAYS ALONG WITH SOME BREEZY CONDITIONS
IN THE AFTERNOON AND EVENING HOURS. FELTON
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...GALE WARNING UNTIL 11 PM PDT THIS EVENING FOR CENTRAL U.S.
WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE U.S. WATERS
STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 11 PM PDT
THIS EVENING FOR ADMIRALTY INLET.
SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 5 AM PDT
THURSDAY FOR COASTAL WATERS FROM CAPE FLATTERY TO JAMES
ISLAND 10 TO 60 NM-COASTAL WATERS FROM CAPE FLATTERY TO
JAMES ISLAND OUT 10 NM-COASTAL WATERS FROM JAMES ISLAND
TO POINT GRENVILLE 10 TO 60 NM-COASTAL WATERS FROM JAMES
ISLAND TO POINT GRENVILLE OUT 10 NM-COASTAL WATERS FROM
POINT GRENVILLE TO CAPE SHOALWATER 10 TO 60 NM-COASTAL
WATERS FROM POINT GRENVILLE TO CAPE SHOALWATER OUT 10 NM.
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