180
FXUS66 KSEW 220329
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
829 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
SOUTHWEST FLOW ALOFT CONTINUES INTO WEDNESDAY WITH A
STRONG UPPER LEVEL RIDGE OVER THE INTERIOR PACIFIC NORTHWEST AND
AN UPPER LOW OFFSHORE OF THE WEST COAST. VFR CONDITIONS FOR MOST
SITES WITH HIGH CLOUDS AT TIMES INTO WEDNESDAY. EMBEDDED
WILDFIRE SMOKE ALOFT WILL CONTINUE TO LIMIT BOTH HORIZONTAL AND
SLANT-RANGE VISIBILITY INTO WEDNESDAY. A BRIEF PERIOD OF
LIFR/IFR CIGS MAY OCCUR AT HQM WEDNESDAY AM. SCATTERED SHOWERS
ASSOCIATED WITH WEAK CONVECTION MAY MOVE NORTHWARDS INTO
WESTERN WASHINGTON WEDNESDAY EVENING INTO THE OVERNIGHT HOURS.
LIGHT WINDS TONIGHT INCREASING FROM THE W/NW ON WEDNESDAY.
KSEA...VFR CONDITIONS WITH HIGH CLOUDS AT TIMES AND SMOKE
ENTRAINED SMOKE ABOVE THE SURFACE. INCREASING HIGH CLOUDS
EXPECTED WEDNESDAY PM. N/NE SURFACE WINDS TONIGHT BECOMING MORE
NW ON WEDNESDAY. JD
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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