276
FXUS66 KSEW 221031
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
331 AM PDT WED JUL 22 2026
SYNOPSIS
UPPER LEVEL RIDGE CENTERED WELL TO THE SOUTHEAST EXTENDING BACK
OVER WESTERN WASHINGTON TODAY. IN THE LOWER LEVELS LIGHT FLOW
WITH A THERMALLY INDUCED SURFACE TROUGH ALONG THE COAST SHIFTING
INLAND THIS AFTERNOON. NEAR RECORD BREAKING HIGHS TODAY.
PATTERN CHANGE TONIGHT INTO THURSDAY WITH REMNANTS OF TROPICAL
STORM ELIDA MOVING THROUGH PRODUCING A CHANCE OF SHOWERS AND
THUNDERSTORMS. UPPER LEVEL TROUGH OFFSHORE FRIDAY MOVING INLAND
OVER THE WEEKEND GIVING THE AREA BELOW NORMAL TEMPERATURES AND A
CHANCE OF SHOWERS. TROUGH MOVES EAST LATER SUNDAY INTO MONDAY
MORNING. UPPER LEVEL TROFINESS OFFSHORE WITH AN UPPER LEVEL
RIDGE WELL TO THE EAST TUESDAY.
SHORT TERM /TODAY THROUGH FRIDAY/
SATELLITE IMAGERY SHOWS STRATUS RIGHT ALONG THE COASTLINE EARLY
THIS MORNING WITH JUST A FEW HIGH CLOUDS OVER THE REMAINDER OF
THE AREA. TEMPERATURES AT 3 AM/10Z WERE IN THE MID 50S TO LOWER
70S ( 70 DEGREES HERE AT THE OFFICE ).
ONE MORE HOT DAY TODAY WITH NEAR RECORD BREAKING HIGH
TEMPERATURES. WESTERN WASHINGTON ON THE BACKSIDE OF A VERY WARM
UPPER LEVEL RIDGE. LOW LEVEL OFFSHORE FLOW THIS MORNING WITH A
THERMALLY INDUCED SURFACE TROUGH ALONG THE COAST. THE THERMAL
TROUGH WILL SHIFT OVER THE PUGET SOUND THIS AFTERNOON. 850 MB
TEMPERATURES IN THE PLUS 20C TO PLUS 23C RANGE THIS AFTERNOON.
HIGHS IN THE 90S WILL BE COMMON FROM SNOHOMISH COUNTY SOUTHWARD
WITH THE WARMEST LOCATIONS IN THE SOUTHWEST INTERIOR AND CASCADE
FOOTHILLS CLOSE TO 100 DEGREES. HIGHS ON THE COAST, NEAR THE
STRAIT OF JUAN DE FUCA AND IN THE NORTHWEST INTERIOR MOSTLY IN
THE 80S. A HEAT ADVISORY FOR MOST OF THE AREA WILL REMAIN IN
EFFECT UNTIL 11 PM TONIGHT.
PATTERN CHANGES TONIGHT AS THE REMNANTS OF WHAT WAS TROPICAL
STORM ELIDA MOVE OFF THE OREGON COAST. LOW LEVEL FLOW TURNING
ONSHORE. FLOW ALOFT BECOMING DIFLUENT OVER WESTERN WASHINGTON
LATE TONIGHT INTO THURSDAY MORNING. THIS COMBINED WITH THE
ARRIVAL OF THE MOISTURE ASSOCIATED WITH ELIDA WILL PRODUCE AT
LEAST A CHANCE OF SHOWERS LATE TONIGHT INTO THURSDAY MORNING.
CONVECTIVE INDEXES ARE MARGINAL WITH MODEL CONSENSUS PUTTING THE
CHANCE FOR THUNDERSTORMS UNDER 15 PERCENT. GIVEN THE REMNANTS
ARE RUNNING INTO AN AIR MASS THAT JUST PRODUCED NEAR RECORD HIGH
TEMPERATURES WILL INCREASE THE THUNDERSTORM CHANCES ENOUGH TO
INCLUDE A SLIGHT CHANCE OF THUNDERSTORMS AS WELL FOR LATE
TONIGHT INTO THURSDAY MORNING. SKIES CLEARING THURSDAY AFTERNOON
FOR THE INTERIOR WITH THE BAND OF SHOWERS NORTHWEST OF THE
AREA. ANOTHER MILD NIGHT TONIGHT WITH LOWS IN THE UPPER 50S TO
MID 60S. MUCH COOLER THURSDAY WITH HIGHS IN THE 70S AND LOWER
80S FOR THE INTERIOR AND MID 60S ALONG THE COAST. THE TRANSITION
TO ONSHORE FLOW WILL PUSH THE SMOKE AWAY FROM WESTERN
WASHINGTON BY THURSDAY AFTERNOON.
REMNANT OF ELIDA REMAINING OFF THE COAST THURSDAY NIGHT INTO
FRIDAY BUT NOTHING SPINNING OUT OF THE LOW OVER THE AREA. 500 MB
HEIGHTS STILL AROUND 580 DMS WITH WEAK LOW LEVEL ONSHORE FLOW.
MARINE LAYER NOT GETTING EAST OF PUGET SOUND FRIDAY MORNING AND
BY AFTERNOON STRATUS WILL JUST BE HUGGING THE COASTLINE. HIGHS
ONCE AGAIN IN THE 70S TO LOWER 80S INLAND AND IN THE MID 60S ON
THE COAST. LOWS FRIDAY MORNING IN THE 50S AND LOWER 60S.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
EXTENDED MODELS IN PRETTY GOOD AGREEMENT WEAKENING THE ELIDA
REMNANTS INTO AN UPPER LEVEL TROUGH THAT MOVES INLAND SATURDAY
BRINGING A CHANCE OF SHOWERS TO MOST OF THE AREA. ANOTHER
SHORTWAVE, THIS ONE ASSOCIATED WITH AN UPPER LEVEL TROUGH OFF
THE BRITISH COLUMBIA COAST, MOVING THROUGH SUNDAY INTO MONDAY
MORNING KEEPING A CHANCE OF SHOWERS OVER AT LEAST THE NORTHERN
PORTIONS. UPPER LEVEL TROFINESS OFFSHORE WITH AN UPPER LEVEL
RIDGE WELL TO THE EAST TUESDAY. VARYING DEGREES OF LOW LEVEL
ONSHORE FLOW THROUGH THE PERIOD WILL KEEP TEMPERATURES SLIGHTLY
ON THE COOL SIDE. HIGHS MID 60S COAST AND UPPER 60S TO MID 70S
INLAND. LOWS MOSTLY IN THE 50S.
AVIATION
HIGH PRESSURE WILL LEAD TO DRY AND STABLE WEATHER OVER WESTERN
WA TODAY. AT THE COAST, A SHALLOW MARINE LAYER WILL BRING IFR TO
LIFR CONDITIONS EARLY THIS MORNING. AN ONSHORE PUSH WILL LEAD
TO MORE EXTENSIVE MARINE CLOUDS ALONG THE COAST TONIGHT AND
THURSDAY. MEANWHILE, MID LEVEL MOISTURE WILL INCREASE THIS
EVENING AND THURSDAY WITH A CHANCE OF HIGH-BASED SHOWERS AND
THUNDERSTORMS OVER THE REGION. SHOWERS WILL MAINLY IMPACT THE
MOUNTAINS THURSDAY AFTERNOON. 33
KSEA...VFR TODAY WITH N WIND 5-10 KT. WINDS WILL SWITCH TO SW
AROUND 06Z TONIGHT WITH POSSIBLE MVFR CIGS BY 12Z. HIGH-BASED
SHOWERS ALSO IN THE VICINITY BY 12Z THURS. 33
MARINE
A THERMAL TROUGH ALONG THE COAST WILL SHIFT INLAND TODAY AND
THURSDAY WITH STRONGER ONSHORE FLOW DEVELOPING. ONSHORE FLOW
WILL CONTINUE FRIDAY THROUGH THE WEEKEND. HIGHEST WINDS AND
WAVES WILL BE THROUGH THE CENTRAL/EAST STRAIT OF JUAN DE FUCA.
33
FIRE WEATHER
ELEVATED FIRE WEATHER CONCERNS CONTINUE TODAY WITH HOT AND DRY
CONDITIONS. MINIMUM RELATIVE HUMIDITIES WILL FALL AS LOW AS 20%
TO 30% AGAIN LATER THIS AFTERNOON, 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. THE FIRE WEATHER WATCH FOR THE SOUTHERN CASCADES AND
SOUTH SOUND AREAS TONIGHT THROUGH THURSDAY AFTERNOON WILL BE
UPGRADED TO A RED FLAG WARNING. INCREASING ONSHORE FLOW
BEGINNING 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
SEW WATCHES/WARNINGS/ADVISORIES
WA...AIR QUALITY ALERT UNTIL 9 AM PDT THIS MORNING 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 THIS 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 THIS EVENING 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...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 5 AM PDT
THURSDAY FOR CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-
EAST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
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