252
FXUS66 KSEW 212245
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
345 PM PDT TUE JUL 21 2026
SYNOPSIS
WARM AND DRY CONDITIONS WITH HIGH CLOUDS AND HAZY SKIES CONTINUE
TONIGHT AND INTO WEDNESDAY. CHANCES FOR SHOWERS AND
THUNDERSTORMS ARRIVE WEDNESDAY NIGHT AND INTO THURSDAY. AN
UPPER LEVEL TROUGH MOVES OVER WESTERN WASHINGTON WITH LOW LEVEL
ONSHORE FLOW FRIDAY THROUGH THE FIRST PART OF NEXT WEEK FOR A
ROUND OF SEASONABLE TEMPERATURES AND SOME ADDITIONAL CHANCES FOR
SHOWERS.
SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/
SATELLITE IMAGERY CONTINUES TO SHOW HIGH CLOUDS AND SOME UPPER
LEVEL SMOKE. WITH THAT, TEMPERATURES HAVE WARMED INTO THE {FILL
IN}. HIGH TEMPERATURES REMAIN ON TRACK TO REACH THE UPPER 80S TO
MID 90S, WITH 70S TO NEAR 80 ALONG THE IMMEDIATE COASTLINES. LOW
TEMPERATURES IN THE LOW TO MID 60S WILL PROVIDE MINIMAL RELIEF
OVERNIGHT. HIGHS LOOK TO GET A LITTLE WARMER ON WEDNESDAY, WITH
MUCH OF THE INTERIOR IN THE 90S, PUSHING 100 IN FAVORED PLACES
SUCH AS THE SOUTHWEST INTERIOR AND THE CASCADE VALLEYS. LUCKILY,
STRONGER ONSHORE FLOW IS ON TRACK TO ARRIVE WEDNESDAY NIGHT INTO
THURSDAY. AREAS ALONG THE OLYMPIC PENINSULA WILL SEE A RETURN TO
LOW TEMPERATURES IN THE UPPER 50S TO NEAR 60 WEDNESDAY NIGHT,
THROUGH ELSEWHERE LOW TO MID 60S REMAIN. THE AMOUNT OF COOLING
WILL DEPEND ON THE CLOUD COVER AND THE STRENGTH OF THE ONSHORE
FLOW, BUT THE OLYMPIC PENINSULA LOOKS TO COOL INTO THE 70S ON
THURSDAY, WITH LOW TO MID 80S EXPECTED ACROSS THE INTERIOR. THIS
WILL PUT AN END TO THE MAJOR HEATRISK (AND THUS THE HEAT
ADVISORY), WITH MOST PLACES RETUNING TO MINOR, THROUGH THE
METRO AREA AND NORTHWARD WILL CONTINUE TO FLIRT WITH MODERATE
HEATRISK.
OUTSIDE OF TEMPERATURES, CONDITIONS LOOK TO BECOME MORE BECOME
MORE ACTIVE WEDNESDAY NIGHT AS A TROUGH OFFSHORE BEINGS TO PULL
IN MOISTURE FROM OREGON, FOR CHANCES OF SHOWERS AND
THUNDERSTORMS. THE BEST CHANCES FOR THUNDERSTORMS WEDNESDAY
NIGHT WILL BE ACROSS THE SOUTHERN WASHINGTON CASCADES AND
PORTIONS OF SOUTHWEST WASHINGTON. SHOWERS AND STORMS ARE
EXPECTED TO DRIFT FROM SOUTH TO NORTH OVERNIGHT WITH CHANCES FOR
STORMS CONTINUING ACROSS THE AREA THURSDAY MORNING.
THUNDERSTORMS SHOULD DEPART THE AREA THURSDAY AFTERNOON. THE
GREATEST UNCERTAINTY IS THE COVERAGE OF THUNDERSTORMS THROUGH
THIS TIME PERIOD. EVEN WITH A MIX OF WET AND DRY THUNDERSTORMS,
NEW FIRE STARTS WILL BE POSSIBLE WITH LIGHTNING STRIKES. A FIRE
WEATHER WATCH HAS BEEN ISSUED FOR PORTIONS OF SOUTHWEST WA AND
THE SOUTHERN CASCADES FROM WEDNESDAY EVENING THROUGH THURSDAY
AFTERNOON.
SMOKE CONTINUES TO LINGER ACROSS THE AREA, PRIMARILY ALOFT,
THROUGH MAY BE MORE NOTICEABLE ACROSS WHATCOM AND SKAGIT
COUNTIES, AS WELL AS HIGHER ELEVATIONS IN THE CASCADES. STRONGER
ONSHORE FLOW WEDNESDAY NIGHT INTO THURSDAY WILL HELP TO PUSH THE
SMOKE EAST OF THE CASCADES.
LONG TERM /FRIDAY THROUGH TUESDAY/
DRIER CONDITIONS ARE EXPECTED ON FRIDAY BEFORE THE LOW PRESSURE
SYSTEM OFFSHORE WILL FINALLY MOVES INLAND AND TRAVERSES THE
REGION SATURDAY. ADDITIONAL SYSTEMS SUNDAY AND INTO EARLY NEXT
WEEK WILL CONTINUE TO KEEP CHANCES FOR SHOWERS IN THE FORECAST.
TEMPERATURES RETURN TO MORE SEASONABLE CONDITIONS WITH HIGHS IN
THE MID 60S TO MID 70S AND LOWS IN THE 50S.
62
AVIATION
HIGH PRESSURE ACROSS THE REGION MAINTAINING VFR CONDITIONS AREA-WIDE
THIS AFTERNOON. SOME PASSING HIGH CLOUDS REMAIN, AS WELL AS
LINGERING LOW CLOUDS OFFSHORE TO THE WEST OF KHQM. EMBEDDED WILDFIRE
SMOKE ALOFT ACROSS PORTIONS OF THE REGION CONTINUES TO LIMIT BOTH
HORIZONTAL AND SLANT-RANGE VISIBILITY THROUGH EARLY WEDNESDAY, BUT
BEGINS TO CLEAR THROUGH THE DAY TOMORROW. AROUND A 50-60% CHANCE OF
IFR RETURNING TO THE IMMEDIATE COAST, INCLUDING KHQM, LATE TONIGHT
THROUGH EARLY WEDNESDAY MORNING.
KSEA...VFR CONDITIONS CONTINUE WITH VARIABLE HIGH CLOUDS WITH SOME
ENTRAINED SMOKE ABOVE THE SURFACE. NO SIGNIFICANT CEILING/VISIBILITY
ISSUES EXPECTED THROUGH THE PERIOD. NORTHERLY SURFACE WINDS THIS
AFTERNOON AND EVENING, EASING OVERNIGHT.
MARINE
STRONG HIGH PRESSURE REMAINS OFFSHORE WITH A THERMAL TROUGH
ALONG THE WA COAST. OVERALL WINDS ARE GENERALLY LIGHT ACROSS THE
COASTAL WATERS WITH SEAS UNDER 6 FT. THE THERMAL TROUGH WILL
SHIFT INLAND WEDNESDAY AND THURSDAY WITH STRONGER ONSHORE
PUSHES EXPECTED THROUGH THE STRAIT OF JUAN DE FUCA WHICH MAY
WARRANT HEADLINES. WEST TO SOUTHWEST WINDS AND SEAS BELOW 6 FT
LOOK TO PERSIST ACROSS THE COASTAL WATERS THURSDAY AND BEYOND.
62
FIRE WEATHER
ELEVATED FIRE WEATHER CONCERNS CONTINUE INTO WEDNESDAY DUE TO
VERY WARM AND DRY CONDITIONS. MINIMUM RELATIVE HUMIDITIES WILL
FALL AS LOW AS 20% TO 30% AGAIN ON WEDNESDAY, WITH DRIER
LOCATIONS ACROSS THE SOUTHERN PUGET SOUND POTENTIALLY BOTTOMING
OUT IN THE TEENS. THERE IS A CHANCE OF THUNDERSTORMS COMING IN
FROM THE SOUTH LATE WEDNESDAY NIGHT INTO EARLY THURSDAY WHICH,
GIVEN THE WARM AND DRY CONDITIONS, COULD CAUSE ADDITIONAL
IGNITIONS FROM LIGHTNING. A FIRE WEATHER WATCH IS IN EFFECT FOR
THE SOUTHERN CASCADES AND SOUTH SOUND AREAS FROM WEDNESDAY NIGHT
THROUGH THURSDAY AFTERNOON. EVEN WITH ONSHORE FLOW WILL
INCREASE LATER THURSDAY BRINGING COOLER TEMPERATURES AND BETTER
OVERNIGHT RH RECOVERIES THROUGH THE WEEKEND INTO THE FIRST PART
OF NEXT WEEK EASING FIRE WEATHER CONCERNS.
FELTON/62
SEW WATCHES/WARNINGS/ADVISORIES
WA...AIR QUALITY ALERT UNTIL 9 AM PDT WEDNESDAY FOR CASCADES OF
WHATCOM AND SKAGIT COUNTIES-FOOTHILLS AND VALLEYS OF THE
NORTH CASCADES-LOWLANDS OF WESTERN SKAGIT AND
NORTHWESTERN SNOHOMISH COUNTIES-LOWLANDS OF WESTERN
WHATCOM COUNTY.
FIRE WEATHER WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY
AFTERNOON FOR BLACK HILLS AND SOUTHWEST INTERIOR LOWLANDS-
WEST SLOPES OF THE CENTRAL CASCADES GENERALLY ABOVE 1500
FEET.
HEAT ADVISORY UNTIL 11 PM PDT WEDNESDAY FOR CITY OF SEATTLE-
DOWNTOWN EVERETT / MARYSVILLE AREA-EASTERN KITSAP COUNTY-
EASTERN STRAIT OF JUAN DE FUCA-EASTSIDE-FOOTHILLS AND
VALLEYS OF CENTRAL KING COUNTY-FOOTHILLS AND VALLEYS OF
PIERCE AND SOUTHERN KING COUNTIES-FOOTHILLS AND VALLEYS
OF SNOHOMISH AND NORTHERN KING COUNTIES-FOOTHILLS AND
VALLEYS OF THURSTON AND LEWIS COUNTIES-FOOTHILLS AND
VALLEYS OF THE NORTH CASCADES-FOOTHILLS OF THE WESTERN
AND SOUTHERN OLYMPIC PENINSULA-LAKE CRESCENT AREA
INCLUDING US 101-LOWLANDS OF LEWIS AND SOUTHERN THURSTON
COUNTIES-LOWLANDS OF PIERCE AND SOUTHERN KING COUNTIES-
LOWLANDS OF WESTERN SKAGIT AND NORTHWESTERN SNOHOMISH
COUNTIES-LOWLANDS OF WESTERN WHATCOM COUNTY-MIDDLE
CHEHALIS RIVER VALLEY-NORTHERN HOOD CANAL-OLYMPIA AND
SOUTHERN PUGET SOUND-PORT TOWNSEND AREA-SHORELINE /
LYNNWOOD / SOUTH EVERETT AREA-SOUTHERN HOOD CANAL.
PZ...NONE.
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