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FXUS66 KSEW 181036
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
336 AM PDT THU JUN 18 2026
SYNOPSIS
UPPER LEVEL RIDGE CENTERED WELL OFFSHORE WITH NORTHERLY
FLOW IN THE LOWER LEVELS. WEAK SYSTEM MOVING BY TO THE NORTH
FRIDAY NIGHT AND SATURDAY. LOW LEVEL FLOW GOING BACK TO
ONSHORE SATURDAY. RIDGE MOVING EAST SUNDAY ENDING UP OVER THE
AREA MONDAY INTO TUESDAY WITH HIGH TEMPERATURES INLAND JUST A
FEW DEGREES SHORT OF RECORDS. TEMPERATURES COOLING WEDNESDAY
WITH DEVELOPING LOW LEVEL ONSHORE FLOW.
SHORT TERM /TODAY THROUGH SATURDAY/
SATELLITE IMAGERY SHOWS STRATUS OVER THE CENTRAL AND SOUTH COAST
EXTENDING AS FAR EAST AS SHELTON AT 3 AM/10Z. CLEAR SKIES OVER
THE REMAINDER OF THE AREA. TEMPERATURES WERE IN THE UPPER 40S TO
MID 50S EXCEPT UPPER 50S IN THE SEATTLE METRO AREA.
STRATUS WILL NOT GET MUCH FURTHER EAST THIS MORNING AND WILL
DISSIPATE BY LATE MORNING. UPPER LEVEL RIDGE CENTERED OFFSHORE
WITH NORTHWESTERLY FLOW ALOFT. LIGHT FLOW IN THE LOWER LEVELS
GOING NORTHERLY THIS AFTERNOON. THIS WILL PUT A CAP ON HIGH
TEMPERATURES NEAR THE WATER. FOR THE MOST PART HIGHS IN THE 70S
AND LOWER 80S INLAND AND LOWER 70S ALONG THE COAST.
UPPER LEVEL RIDGE REMAINING OFFSHORE TONIGHT INTO FRIDAY. FLOW
ALOFT TURNING WEST SOUTHWESTERLY THROWING A FEW HIGH CLOUDS OVER
WESTERN WASHINGTON AT TIMES. LOWS TONIGHT IN THE UPPER 40S TO
MID 50S. HIGHS FRIDAY A FEW DEGREES WARMER INLAND, IN THE 70S TO
MID 80S. AFTERNOON SEABREEZE ALONG THE COAST KEEPING HIGHS
NEAR 70.
WEAK SYSTEM RIDING BY TO THE NORTH LATE FRIDAY NIGHT INTO
SATURDAY. THIS WILL COOL THE TEMPERATURES ALOFT OVER THE AREA
AND INDUCE A WEAK MARINE PUSH IN THE LOWER LEVELS SATURDAY
MORNING. THE COMBINATION OF THESE TWO VARIABLES WILL LOWER HIGH
TEMPERATURES SATURDAY BY 5 TO 10 DEGREES WITH UPPER 60S TO MID
70S OVER THE INTERIOR AND LOWER TO MID 60S ALONG THE COAST. LOWS
FRIDAY NIGHT IN THE UPPER 40S TO MID 50S.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
UPPER LEVEL RIDGE OFFSHORE REBUILDING SATURDAY NIGHT AND SUNDAY.
RIDGE AXIS MOVING OVER WESTERN WASHINGTON MONDAY AND TUESDAY. IN
THE LOWER LEVELS LOW LEVEL ONSHORE FLOW SATURDAY NIGHT GOING
LIGHT SUNDAY. THERMALLY INDUCED SURFACE TROUGH MOVING UP FROM
THE SOUTH REACHING WESTERN WASHINGTON MONDAY MORNING. THE
THERMAL TROUGH WILL REMAIN OVER THE AREA THROUGH TUESDAY NIGHT THEN
SHIFT EAST WEDNESDAY.
HIGHS SUNDAY IN THE 60S ALONG THE COAST AND 70S TO LOWER 80S
INLAND. MONDAY AND TUESDAY WILL BE THE PEAK OF THE WARM
TEMPERATURES THIS ROUND WITH 80S AND LOWER 90S INLAND. HIGHS ON
THE COAST PEAKING MONDAY IN THE 70S BEFORE COOLING BACK INTO THE
60S TUESDAY. COOLING TREND STARTING WEDNESDAY FOR THE INTERIOR
WITH HIGHS IN THE 70S AND LOWER 80S.
MODERATE HEATRISK OVER THE INTERIOR MONDAY AND TUESDAY WILL DROP
BACK DOWN TO THE MINOR CATEGORY WEDNESDAY.
AVIATION
VFR CONDITIONS EARLY THIS MORNING FOR INTERIOR TERMINALS. LATEST
SATELLITE IMAGERY SHOWS MARINE STRATUS CONTINUING TO DEVELOP ALONG
THE COAST. THERE IS A 40-60% CHANCE OF MVFR CIGS EXPECTED BETWEEN
10Z-16Z, WITH A SLIGHT CHANCE (10-25%) OF IFR/LIFR CIGS. IMPROVEMENT
EXPECTED IN THE AFTERNOON ALONG THE COAST. WIDESPREAD VFR CONDITIONS
EXPECTED THIS AFTERNOON. ANOTHER ROUND OF MVFR CIGS POSSIBLE (40-60%
CHANCE) ALONG THE COAST TONIGHT. LIGHT TO VARIABLE WINDS EARLY THIS
MORNING WILL INCREASE THIS AFTERNOON FROM THE NORTH TO 8-12 KT.
WINDS WILL EASE OVERNIGHT.
KSEA...VFR CONDITIONS TODAY WITH HIGH CLOUDS AT TIMES. LIGHT WINDS
THIS MORNING WILL INCREASE THIS AFTERNOON TO 7-10 KT FROM THE N/NW.
WINDS WILL SHIFT NE THIS EVENING AFTER 05Z-06Z AT 5-7 KT.
29
MARINE
BROAD HIGH PRESSURE OVER THE NE PACIFIC WILL CONTINUE INTO NEXT
WEEK, MAINTAINING NORTHERLY SURFACE FLOW ACROSS AREA WATERS. WEAK
HIGH PRESSURE OVER ARE WATERS WILL WEAKEN LATE TONIGHT INTO FRIDAY
AS A LOW PRESSURE SYSTEM PASSES OVER BRITISH COLUMBIA. HIGH PRESSURE
WILL REBUILD OVER AREA WATERS ON SATURDAY AND STRENGTHEN INTO EARLY
NEXT WEEK.
A COMBINATION OF ELEVATED SEAS AND WINDS WILL CONTINUE ACROSS THE
COASTAL WATERS THROUGH SATURDAY, LIKELY REQUIRING THE EXTENSION OF
THE SMALL CRAFT ADVISORY. DIURNAL PUSHES THROUGH THE STRAIT OF JUAN
DE FUCA EXPECTED THIS FRIDAY INTO EARLY NEXT WEEK. THE WINDS ON
FRIDAY AND THE WEEKEND LOOK TO REMAIN BELOW SMALL CRAFT CRITERIA (25-
40% CHANCE). HOWEVER, THE WINDS ON TUESDAY WILL BE STRONGER WITH A
HIGHER CHANCE (40-65%) OF WINDS EXCEEDING 21 KT.
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FIRE WEATHER
ELEVATED FIRE WEATHER CONCERNS FRIDAY AND AGAIN NEXT MONDAY AND
TUESDAY WITH MINIMUM RELATIVE HUMIDITY VALUES DROPPING TO BELOW
30 PERCENT. IN SOME LOCATIONS MONDAY AND TUESDAY MINIMUM RH
VALUES WILL BE AS LOW AS THE TEENS. FUELS WILL CONTINUE TO DRY
AND THE ATMOSPHERE MAY BECOME CONDITIONALLY UNSTABLE WITH THE
SURFACE THERMAL TROUGH MONDAY AND TUESDAY. EVEN THOUGH THE FUELS
HAVE NOT REACHED CRITICAL LEVELS FINE FUELS LIKE GRASS AND BRUSH
WILL IGNITE QUICKLY WITH IT BEING SO DRY. LETS BE CAREFUL OUT
THERE THE NEXT FEW DAYS.
WITH THE FLOW ALOFT OUT OF THE WEST SMOKE FROM EASTERN
WASHINGTON WILL NOT MAKE ITS WAY INTO WESTERN WASHINGTON. FELTON
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM PDT FRIDAY 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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