229
FXUS66 KSEW 191732
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
1032 AM PDT FRI JUN 19 2026
UPDATE
NO CHANGES MADE TO THE INHERITED FORECAST. THE PREVIOUS
DISCUSSION REMAINS BELOW ALONG WITH AN UPDATED MARINE/AVIATION
SECTION.
SYNOPSIS
UPPER LEVEL RIDGE CENTERED OFFSHORE TODAY WILL WEAKEN TONIGHT
AND SATURDAY AS A SYSTEM MOVES BY TO THE NORTH. THE RIDGE WILL
REBUILD SUNDAY WITH THE RIDGE AXIS MOVING OVER WESTERN
WASHINGTON MONDAY AND TUESDAY. THERMALLY INDUCED SURFACE TROUGH
DEVELOPING ALONG THE COAST SUNDAY NIGHT WILL REMAIN OVER THE
AREA THROUGH TUESDAY. THERMAL TROUGH MOVING EAST TUESDAY NIGHT
WITH THE UPPER LEVEL RIDGE WEAKENING THURSDAY. UPPER LEVEL
TROUGH APPROACHING THE COAST LATE THURSDAY.
SHORT TERM /TODAY THROUGH SUNDAY/
SATELLITE IMAGERY SHOWS HIGH CLOUDS OVER THE SOUTHERN PORTION OF
THE AREA THIS MORNING WITH CLEAR SKIES NEAR THE CANADIAN BORDER.
TEMPERATURES AT 3 AM/10Z WERE IN THE 50S AND LOWER 60S EXCEPT IN
THE SEATTLE METRO AREA WHERE TEMPERATURES WERE IN THE MID 60S.
UPPER LEVEL RIDGE CENTERED OFFSHORE EXTENDING OVER THE AREA
TODAY. LIGHT NORTHERLY FLOW IN THE LOWER LEVELS. HIGHS WELL
ABOVE NORMAL, IN THE UPPER 70S TO UPPER 80S INLAND AND UPPER 60S
TO MID 70S COAST.
UPPER LEVEL RIDGE WEAKENING TONIGHT AND SATURDAY AS A WEATHER
SYSTEM MOVES THROUGH BRITISH COLUMBIA. LOW LEVEL FLOW GOING
ONSHORE TONIGHT BRINGING COOLER MARINE AIR INTO WESTERN
WASHINGTON. LOWS TONIGHT IN THE UPPER 40S TO MID 50S. HIGHS
SATURDAY IN THE LOWER TO MID 70S INLAND AND MID 60S COAST.
UPPER LEVEL RIDGE REBUILDING SATURDAY NIGHT INTO SUNDAY. LOW
LEVEL ONSHORE FLOW WEAKENING SATURDAY NIGHT WITH THE LOW LEVEL
FLOW GOING NORTHERLY AGAIN SUNDAY. HIGHS REBOUNDING INTO THE MID
70S TO MID 80S INTERIOR AND UPPER 60S TO MID 70S COAST. LOWS
SATURDAY NIGHT IN THE UPPER 40S TO MID 50S.
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
THERMALLY INDUCED SURFACE TROUGH DEVELOPING ALONG THE COAST
SUNDAY NIGHT. UPPER LEVEL RIDGE OFFSHORE MOVING EAST WITH THE
RIDGE AXIS OVER WESTERN WASHINGTON MONDAY. INCREASING LOW LEVEL
OFFSHORE FLOW PUSHING HIGHS INTO THE 80S TO LOWER 90S INLAND
AND LOWER TO MID 80S FOR THE COAST. LOWS IN THE 50S.
LITTLE CHANGE IN THE PATTERN MONDAY NIGHT INTO TUESDAY WITH THE
THERMALLY INDUCED SURFACE TROUGH STILL IN THE AREA AND THE UPPER
LEVEL RIDGE CENTERED OVER WESTERN WASHINGTON. HIGHS A COUPLE OF
DEGREES WARMER OVER THE INTERIOR, 80S TO MID 90S. AFTERNOON
SEABREEZES ALONG THE COAST WITH THE THERMALLY INDUCED SURFACE
TROUGH STARTING TO MOVE INLAND KEEPING HIGHS IN THE UPPER 70S TO
MID 80S. LOWS IN THE MID 50S TO MID 60S. THERE IS A CHANCE FOR
RECORD BREAKING HIGHS AND RECORD HIGH MINIMUM TEMPERATURES
TUESDAY.
THERMALLY INDUCED TROUGH MOVING EAST OF THE CASCADES TUESDAY
NIGHT INTO WEDNESDAY. UPPER LEVEL RIDGE REMAINING OVER THE AREA
WITH 500 MB HEIGHTS STILL IN THE MID 580 DMS. LOW LEVEL FLOW
GOING ONSHORE COOLING HIGHS OVER THE INTERIOR 5 TO 10 DEGREES
VERSUS TUESDAY, IN THE MID 70S TO MID 80S. HIGHS ALONG THE COAST
IN THE MID AND UPPER 60S. RECORD HIGH MINIMUMS AGAIN POSSIBLE
TUESDAY NIGHT WITH LOWS IN THE MID 50S TO LOWER 60S.
UPPER LEVEL RIDGE WEAKENING WEDNESDAY NIGHT INTO THURSDAY WITH
AN UPPER LEVEL TROUGH APPROACHING THE AREA LATE THURSDAY. BY
06Z FRIDAY THE TROUGH AXIS WILL BE NEAR 130W. THIS FORECAST
PACKAGE ONLY GOES THROUGH THURSDAY SO THE FORECAST IS STILL DRY.
IF THE PATTERN HOLDS UP THERE WILL BE A CHANCE OF SHOWERS
FRIDAY. THIS WOULD BE THE FIRST RAIN IN WESTERN WASHINGTON IN
TWO WEEKS. SEATTLE LAST RECORDED MEASURABLE RAIN ON JUNE 9TH.
WITH THE WELL ABOVE NORMAL HIGH TEMPERATURES AND WARM LOW
TEMPERATURES MODERATE HEATRISK ACROSS WESTERN WASHINGTON MONDAY
AND TUESDAY. IF THE FORECAST TREND CONTINUES LOOK FOR A HEAT
ADVISORY FOR MONDAY AND TUESDAY TO BE ISSUED SOMETIME OVER THE
WEEKEND.
SEATTLE HAS A CHANCE TO REACH 90 DEGREES MONDAY WITH A BETTER
CHANCE TUESDAY. IT IS RARE FOR SEATTLE TO HAVE 2 90 DEGREE PLUS
DAYS IN JUNE. IN 81 YEARS OF RECORDS THERE HAVE ONLY BEEN 10
YEARS WITH TWO OR MORE 90 DEGREE PLUS DAYS IN JUNE. THE RECORD
FOR THE MONTH IS 3 DAYS IN 1992, 1995 AND THE MEMORABLE HEAT
DOME OF 2021. FELTON
AVIATION
VFR CONDITIONS WITH MID TO HIGH CLOUDS TODAY. INCREASED ONSHORE
FLOW EVENING/TONIGHT WILL BRING INCREASED CHANCES FOR WIDESPREAD
MVFR CIGS. HIGHEST CHANCES (70-90%) ARE ALONG THE COAST AFTER 02Z,
WITH A SLIGHT CHANCE (20%) OF IFR CIGS BETWEEN 04Z AND 14Z. FOR
INTERIOR TERMINALS, CHANGES RANGE BETWEEN 25-50% BETWEEN 11Z AND
16Z. WINDS THIS AFTERNOON 6-12 KTS. SOUTHWEST (ONSHORE) WINDS AFTER
AFTER 06Z-08Z SATURDAY.
KSEA...VFR CONDITIONS TODAY WITH MID TO HIGH CLOUDS. ONSHORE FLOW
STARTING FRIDAY EVENING WILL INTRODUCE THE CHANCES FOR MVFR CIGS
SATURDAY MORNING. LATEST GUIDANCE HAS A 25-50% CHANCE OF MVFR
CIGS AFTER 11Z. VFR CONDITIONS RETURN AFTER 20Z SATURDAY. W/NW THIS
AFTERNOON TO 6-8 KT. INCREASING SW WINDS AFTER 06Z-08Z AT 6-9 KT.
MARINE
BROAD HIGH PRESSURE OVER THE OFFSHORE WATERS OF THE PACIFIC RETREATS
TO THE WEST AS A LOW PRESSURE SYSTEM MOVES THROUGH BRITISH COLUMBIA
TODAY AND SATURDAY, CAUSING HIGH PRESSURE OVER WASHINGTON'S WATERS
TO CONTINUE TO WEAKEN. ONCE THE LOW PRESSURE SYSTEM PUSHES EAST,
HIGH PRESSURE WILL QUICKLY REBUILD OVER AREA WATERS LATE SATURDAY
EVENING AND WILL STRENGTHEN THROUGH MIDWEEK.
ELEVATED WINDS AND SEAS WILL CONTINUE FOR THE COASTAL WATERS THROUGH
SATURDAY MORNING AND WILL BEGIN TO SUBSIDE IN THE AFTERNOON. STRONG
NORTHERLY FLOW WILL CAUSE SEAS TO BUILD TO 10-15 FT THIS EVENING
THROUGH SATURDAY MORNING. AS HIGH PRESSURE CONTINUES TO STRENGTHEN
OVER THE WATERS EARLY NEXT WEEK, INCREASED NORTHWESTERLY FLOW OVER
THE COASTAL WATERS WILL BRING THE CHANCES OF SMALL CRAFT WINDS
TUESDAY THROUGH THURSDAY, WITH THE LATEST PROBABILITIES AROUND 50-
80%. DIURNAL PUSHES THROUGH THE STRAIT OF JUAN DE FUCA WILL ALSO
BEGIN TODAY AND WILL CONTINUE INTO NEXT WEEK. IN ADDITION, GUIDANCE
IS HIGHLIGHTING A 40-50% CHANCES FOR GALES IN THE STRAIT OF JUAN DE
FUCA ON TUESDAY THROUGH AT LEAST THURSDAY.
FIRE WEATHER
ELEVATED FIRE WEATHER CONCERNS TODAY AND AGAIN MONDAY AND
TUESDAY WITH MINIMUM RELATIVE HUMIDITY VALUES DROPPING INTO THE
30S. IN SOME LOCATIONS MONDAY AND TUESDAY, MINIMUM RH VALUES
WILL BE AS LOW AS THE TEENS AND 20S. FUELS WILL CONTINUE TO DRY
AND THE ATMOSPHERE MAY BECOME CONDITIONALLY UNSTABLE WITH THE
SURFACE THERMAL TROUGH MONDAY AND TUESDAY. FUELS ARE GETTING
CLOSE TO CRITICAL LEVELS. EVEN WITHOUT HITTING CRITICAL LEVELS
NEEDED FOR RED FLAG WARNINGS TO BE ISSUED, FINE FUELS LIKE
GRASS AND BRUSH WILL IGNITE QUICKLY WITH IT BEING SO DRY. LETS
CONTINUE TO BE CAREFUL OUT THERE. FELTON
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 1 PM THIS AFTERNOON TO 11 AM PDT
SATURDAY FOR COASTAL WATERS FROM CAPE FLATTERY TO JAMES
ISLAND OUT 10 NM-COASTAL WATERS FROM JAMES ISLAND TO
POINT GRENVILLE OUT 10 NM-COASTAL WATERS FROM POINT
GRENVILLE TO CAPE SHOALWATER OUT 10 NM.
SMALL CRAFT ADVISORY UNTIL 5 PM PDT SATURDAY 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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