696
FXUS66 KSEW 200356
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
855 PM PDT FRI JUN 19 2026
SYNOPSIS
UPPER-LEVEL RIDGE OFFSHORE WILL WEAKEN TONIGHT AND SATURDAY AS
A SYSTEM GLANCES BY TO THE NORTH. THE RIDGE WILL REBUILD SUNDAY
AS ITS AXIS MOVES OVER WESTERN WASHINGTON MONDAY AND TUESDAY.
THIS SET UP WILL KICK-START A PERIOD OF WELL-ABOVE AVERAGE
TEMPERATURES AS HEATRISK BECOMES A CONCERN. CONDITIONS ARE
FAVORED TO TREND COOLER TOWARDS THE SECOND HALF OF THE WEEK.
SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/
AN UPPER-LEVEL RIDGE WILL LOSE INFLUENCE THIS EVENING AS A LOW
CENTER TRAVERSES TO THE NORTH OVER BC. AS A RESULT, LOW-LEVEL
ONSHORE FLOW IS FORECAST TO INCREASE AS AN INTRUSION OF MARINE
COOLED AIR TAKES HOLD OF WESTERN WASHINGTON. MARINE STRATUS WILL
INCREASE IN COVERAGE TONIGHT AS PORTIONS OF WESTERN WA WAKES UP
TO MOSTLY CLOUDY TO OVERCAST SKIES ON SATURDAY. OVERNIGHT LOWS
WILL FALL TO THE UPPER 40S TO MID 50S.
AS MENTIONED - IT'LL BE A CLOUDY START TO THE DAY FOR AREAS
ACROSS W WA ON SATURDAY. HOWEVER, THE MARINE LAYER WILL
GRADUALLY BURN OFF AS THE DAY PROGRESS GIVING WAY TO MOSTLY
CLEAR SKIES BY THE AFTERNOON. DAYTIME HIGHS ARE FORECAST TO TOP
OUT IN THE LOWER TO MID 70S, AROUND SEASONAL AVERAGE. SATURDAY
WILL LIKELY BE THE COOLEST DAY FOR THE NEXT SEVERAL DAYS AS
CONDITIONS ARE EXPECTED TO WARM UP RATHER SIGNIFICANTLY INTO
EARLY NEXT WEEK. WARMER CONDITIONS WILL KICK INTO GEAR ON
SUNDAY AS AN UPPER-LEVEL RIDGE BUILDS OFFSHORE AND BEGINS ITS
GENTLE PROGRESSION LANDWARD. HIGH TEMPERATURES ARE EXPECTED TO
REBOUND BACK INTO THE UPPER 70S TO MID 80S. OVERNIGHT LOWS WILL
GENERALLY FALL INTO THE 50S FOR BOTH SATURDAY AND SUNDAY.
LONG TERM /MONDAY THROUGH FRIDAY/
ENSEMBLES ARE IN LOCK-STEP IN THE POSITIONING OF AN UPPER-LEVEL
RIDGE OVERHEAD ON MONDAY AND IT'S AXIS EAST OF THE CASCADES ON
TUESDAY. A SURFACE THERMAL TROUGH LOOKS TO ALSO DEVELOP AND
SNAKE ALONG THE US WEST COAST - LEADING TO INCREASED OFFSHORE
FLOW. DAYTIME HIGHS WILL WARM INTO THE UPPER 80S TO UPPER 90S
WITH THE HOTTEST DAY ON TUESDAY. THERE IS A CHANCE FOR
RECORD BREAKING HIGHS AND RECORD HIGH MINIMUM TEMPERATURES
TUESDAY AS WELL. WIDESPREAD MODERATE HEATRISK IS FAVORED ALONG
WITH A 20-30% CHANCE OF MAJOR HEATRISK ACROSS URBAN CENTERS
MONDAY THROUGH TUESDAY.
A GRADUAL COOL-DOWN IS AT PLAY MIDWEEK ONWARD. CONDITIONS WILL
STILL REMAIN WARM ON WEDNESDAY WITH HIGHS IN THE 80S TO NEAR 90.
HOWEVER, NEAR-SEASONAL CONDITIONS MAY RETURN BY FRIDAY AS
GUIDANCE IS HINTING AS THE PROGRESSION OF AN UPPER-LEVEL THROUGH
THE REGION.
AVIATION
WIDESPREAD VFR CONDITIONS THIS EVENING WITH GENERALLY CLEAR SKIES
OVER MUCH OF W WA. INCREASED ONSHORE FLOW THIS EVENING AND TONIGHT
WILL BRING AN INCREASE IN CLOUDS OVERNIGHT WITH WIDESPREAD MVFR CIGS
EXPECTED BY EARLY SATURDAY MORNING. 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, CHANCES RANGE BETWEEN
25-50% BETWEEN 11Z AND 16Z. VFR CONDITIONS EXPECTED TO RETURN BY
TOMORROW AFTERNOON. WESTERLY WINDS THIS EVENING 6-12 KTS WITH SOME
VARIANCES TO THE NW OR SW. MORE UNIFORM SOUTHWESTERLY WINDS AFTER
AFTER 06Z-08Z TONIGHT WITH SPEEDS RANGING 8-14 KTS.
KSEA...VFR CONDITIONS THIS EVENING INTO TONIGHT. INCREASING ONSHORE
FLOW STARTING THIS EVENING WILL INTRODUCE THE CHANCES FOR MVFR CIGS
BY SATURDAY MORNING AS DISCUSSED ABOVE. LATEST GUIDANCE HAS A 25-40%
CHANCE OF MVFR CIGS BETWEEN 11Z AND 18Z. VFR CONDITIONS RETURN
AFTER. SW WINDS 6-8 KT, INCREASING 06Z-08Z TO 6-12 KT.
18
MARINE
BROAD HIGH PRESSURE OVER THE OFFSHORE WATERS OF THE PACIFIC RETREATS
TO THE WEST AS A LOW PRESSURE SYSTEM MOVES THROUGH BRITISH COLUMBIA
THIS AFTERNOON 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 AND WILL BEGIN TO SUBSIDE IN THE LATE AFTERNOON TO EVENING.
STRONG NORTHERLY FLOW WILL CAUSE SEAS TO BUILD TO 10-15 FT THIS
EVENING THROUGH SATURDAY EVENING. 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 ON MONDAY AND TUESDAY WITH
MINIMUM RELATIVE HUMIDITY VALUES DROPPING INTO THE 20S IN
CASCADE VALLEYS. CAN'T RULE OUT ISOLATED TEENS AS WELL. 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.
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 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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