658
FXUS66 KSEW 170405
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
905 PM PDT WED JUL 16 2025
SYNOPSIS
WARM AND DRY CONDITIONS EXPECTED TO CONTINUE INTO
THURSDAY. HOWEVER, ONSHORE FLOW WILL GRADUALLY INCREASE THROUGH
THE REST OF THE WEEK, RESULTING IN MORE MODERATE TEMPERATURES OVER
THE WEEKEND AND INTO EARLY NEXT WEEK WITH MORE CLOUD COVER. AN
UPPER LEVEL LOW WILL BRING A SLIGHT CHANCE OF SHOWERS OVER THE
CASCADES MONDAY AND TUESDAY.
SHORT TERM /TONIGHT THROUGH SATURDAY/
QUITE THE GRADIENT IN
TEMPERATURES ACROSS THE REGION TONIGHT, WITH AREAS WEST OF THE
SOUND RANGING FROM THE 50S ALONG THE COAST TO THE 70S FURTHER
INLAND ALONG THE KITSAP PENINSULA. MEANWHILE, AREAS EAST OF THE
SOUND REMAIN IN THE 70S AND 80S THIS EVENING. ONSHORE FLOW HAS
ALLOWED FOR WINDS TO TRANSITION BACK TO THE WEST/NORTHWEST ACROSS
THE REGION TONIGHT AND EXPECT THIS TO BRING SOME RELIEF TO AREAS
GENERALLY WEST OF THE SOUND. HOWEVER, THE MARINE LAYER REMAINS
SHALLOW AND ANOTHER WARM AND DRY DAY IS ON TAP FOR MUCH OF THE
AREA ON THURSDAY. THE FORECAST LARGELY REMAINS ON TRACK TONIGHT,
SO THE REMAINDER OF THE PREVIOUS DISCUSSION FOLLOWS BELOW, WITH
UPDATES MADE TO THE AVIATION AND FIRE SECTIONS. 14
THE BIGGEST QUESTION OF THE HEAT GOING INTO TOMORROW IS HOW MUCH
RELIEF WILL BE PROVIDED THE RETURN OF ONSHORE FLOW INTO THE
REGION. THE HREF ENSEMBLES MEMBERS HAVE WINDS BEGINNING TO
INCREASE OUT OF THE SOUTHWEST TONIGHT/THURSDAY MORNING ALONG THE
COAST, WHICH WILL COOL TEMPERATURES ALONG THE PACIFIC BACK TO NEAR
NORMAL. THE WINDS IN MOST ENSEMBLE MEMBERS STRUGGLE TO GET ANY
BREEZE PAST OLYMPIA THURSDAY UNTIL THE EVENING TIMEFRAME. AREAS
THAT DO GET WIND (OLYMPIA/CHEHALIS VALLEY AND AREAS NORTHWEST)
WILL SEE COOLER TEMPERATURES TONIGHT WITH LOWS IN THE LOW 50S. THE
MORE URBAN AREAS (TACOMA NORTHWARD UP TO BELLINGHAM) WILL SEE MID
AND UPPER 50S FOR LOWS TONIGHT (AND A FEW LOW 60S IN THE SEATTLE
METRO).
HIGHS WILL STILL BE WARM (BUT A FEW DEGREES COOLER COMPARED TO
WEDNESDAY), WITH HIGHS REACHING THE LOW TO UPPER 80S IN INTERIOR
AREAS. THE PREVIOUSLY MENTIONED AREAS GETTING THE ONSHORE
SEABREEZE WILL SEE LOWER HEATRISK IMPACTS (ONLY MINOR), WHILE
INTERIOR AREAS NOT RECEIVING WIND WILL CONTINUE TO SEE MODERATE
HEATRISK IMPACTS UNTIL THE SEABREEZE ARRIVES THURSDAY EVENING.
HAVE ELECTED TO EXTEND THE HEAT ADVISORY FROM TACOMA UP TO
BELLINGHAM (INCLUDING CASCADE FOOTHILLS) THROUGH 5 PM PDT THURSDAY
DUE TO THE MODERATE HEATRISK/WARMER OVERNIGHT TEMPERATURES, AND
LACK OF A BREEZE.
THE ONSHORE FLOW WILL CONTINUE TO REDUCE TEMPERATURES FRIDAY AND
SATURDAY AS THE ONSHORE FLOW/NORTHWEST FLOW ALOFT INCREASES. A
TROUGH DOES PASS THROUGH FRIDAY INTO SATURDAY WITH A COOL FRONT,
BUT NO PRECIPITATION IS EXPECTED (JUST AN INCREASE OF CLOUDS
FRIDAY AFTERNOON INTO SATURDAY). HIGH TEMPERATURES IN INTERIOR
AREAS FRIDAY WILL RANGE FROM 70S TO LOW 80S, AND THIS DROPS TO THE
LOW TO MID 70S SATURDAY.
ADDITIONALLY, SOME HAZE/SMOKE FROM FIRES IN WESTERN WA WILL BE
PRESENT (BUT GENERALLY LIGHT IN COVERAGE NEAR SURFACE AND ALOFT).
LONG TERM /SUNDAY THROUGH WEDNESDAY/
THE COOL PATTERN CONTINUES
THROUGH THE WEEKEND INTO EARLY NEXT WEEK WITH HIGHS REMAINING
STEADY IN THE 70S. THERE IS A WARMING TREND IN THE ENSEMBLES GOING
TOWARDS MIDWEEK, BUT THIS IS NOT EXPECTED TO PRODUCE HEAT IMPACTS
AT THIS TIME. SKY COVERAGE WILL BE A MIX OF CLOUDS AND SUN, WITH A
FEW MORNINGS SEEING INCREASE CLOUD COVERAGE FROM MARINE PUSHES.
THERE IS A SLIGHT CHANCE OF SHOWERS IN THE CASCADES MONDAY/TUESDAY
WITH A TROUGH/FRONT PASSING THROUGH.
HPR
AVIATION
VFR CONDITIONS PERSIST ACROSS THE AREA TERMINALS THIS
EVENING AND WILL CONTINUE FOR THE MAJORITY OF THE TERMINALS
OVERNIGHT. GUIDANCE DOES HINT AT THE POTENTIAL FOR LOWERED
CEILINGS TO RETURN TO COASTAL TERMINALS, LIKE KHQM, AS ONSHORE
FLOW PUSHES STRATUS INLAND OVERNIGHT. THERE REMAINS UNCERTAINTY IN
JUST HOW FAR EAST THE STRATUS WILL PUSH, HOWEVER. AT THIS TIME,
THERE IS HIGH CONFIDENCE THAT AREAS ALONG THE COAST WILL GO DOWN
TO IFR/LIFR BETWEEN 06-09Z AND A 30%-40% CHANCE OF MVFR CEILINGS
DEVELOPING ALONG THE KITSAP PENINSULA (KPWT) AND SOUTHERN INTERIOR
(KOLM). IMPROVEMENT BACK TOWARDS VFR IS EXPECTED AROUND 18-20Z
FOR THE AREA TERMINALS.
SURFACE WINDS ACROSS THE AREA HAVE PRIMARILY SHIFTED BACK TO W/NW
THIS EVENING, PERSISTING AT 6-9 KT. WINDS WILL EASE, BECOMING
LIGHT, AND WILL SHIFT BACK TO THE SW OVERNIGHT.
KSEA...VFR CONDITIONS ARE EXPECTED TO PERSIST THROUGHOUT THE TAF
PERIOD. NW WINDS PERSISTING AT 7-9 KT THIS EVENING WILL EASE TO
3-5 KT AND SHIFT BACK TO THE SW OVERNIGHT. WINDS LOOK TO INCREASE
TO 7-9 KT AGAIN THURSDAY AFTERNOON AND SHIFT BACK TO THE NW.
29/14
MARINE
ELEVATED WINDS AND WAVES THIS EVENING THROUGH THURSDAY
MORNING ALONG THE OUTER COASTAL WATERS, WITH AN OCCASIONAL GUST OF
30 KT POSSIBLE. A SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH
EARLY THURSDAY MORNING. SURFACE HIGH PRESSURE WILL REMAIN SITUATED
WEST OF AREA WATERS, KEEPING NORTHWESTERLY FLOW OVER THE COASTAL
WATERS. ON THURSDAY, A LOW PRESSURE SYSTEM WILL MOVE OVER THE
COASTAL WATERS, WITH A FRONT STALLING NEAR THE WASHINGTON/BRITISH
COLUMBIA BORDER. THE FRONT WILL MOVE OVER THE WATERS EARLY FRIDAY
MORNING, BRINGING SUSTAINED WIND SPEEDS TO AROUND 21 KT FOR THE
OUTER COASTAL WATERS. HIGH PRESSURE WILL REBUILD OVER THE WATERS
FRIDAY EVENING AND PERSIST INTO THE WEEKEND. HIGH PRESSURE WILL
WEAKEN EARLY NEXT WEEK. WESTERLY PUSHES ALONG THE STRAIT OF JUAN DE
FUCA WILL OCCUR EACH EVENING. THE NEXT PUSH THAT LOOKS TO APPROACH
SMALL CRAFT CRITERIA IS FRIDAY EVENING, WITH CURRENT PROBABILITIES
AT 60%-70% OF 21 KT OR GREATER.
SEAS WILL CONTINUE BUILDING TODAY TO 6-11 FT, WITH THE HIGHEST
WAVE HEIGHTS EXPECTED OVER THE OUTER COASTAL WATERS. SEAS WILL
GRADUALLY SUBSIDE THROUGHOUT THE DAY ON THURSDAY AND FRIDAY. SEAS
LOOK TO REMAIN BELOW 3-5 FT INTO THE WEEKEND AND NEXT WEEK.
29
FIRE WEATHER
CRITICAL FIRE WEATHER CONDITIONS WILL COME TO AN
END ACROSS THE CASCADES TONIGHT. WINDS HAVE SHIFTED BACK TO WESTERLY,
MAINLY FOR AREAS TO THE WEST AND SOUTH OF PUGET SOUND, WITH AN
ONSHORE MARINE PUSH THIS EVENING. HOWEVER, EXPECT THE INITIAL
MARINE PUSH TO BE SHALLOW, SO RHS WILL BE SLOW TO RECOVER AGAIN
OVERNIGHT. ELEVATED FIRE CONDITIONS WILL CONTINUE INTO THURSDAY
WITH ANOTHER WARM AND DRY DAY EXPECTED ACROSS THE AREA. A COOLING
TREND WILL COMMENCE LATER THIS WEEK, WITH A RETURN OF COOLER AND
MORE HUMID CONDITIONS THROUGH THE WEEKEND.
SEW WATCHES/WARNINGS/ADVISORIES
WA...RED FLAG WARNING UNTIL 11 PM PDT THIS EVENING FOR WEST SLOPES OF
THE CENTRAL CASCADES GENERALLY ABOVE 1500 FEET-WEST SLOPES
OF THE NORTH CASCADES GENERALLY ABOVE 1500 FEET.
HEAT ADVISORY UNTIL 5 PM PDT THURSDAY FOR CITY OF SEATTLE-
DOWNTOWN EVERETT / MARYSVILLE AREA-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 THE NORTH CASCADES-LOWLANDS OF PIERCE AND SOUTHERN KING
COUNTIES-LOWLANDS OF WESTERN SKAGIT AND NORTHWESTERN
SNOHOMISH COUNTIES-LOWLANDS OF WESTERN WHATCOM COUNTY-
SHORELINE / LYNNWOOD / SOUTH EVERETT AREA.
HEAT ADVISORY UNTIL 10 PM PDT THIS EVENING FOR EASTERN KITSAP
COUNTY-FOOTHILLS AND VALLEYS OF THURSTON AND LEWIS COUNTIES-
LOWLANDS OF LEWIS AND SOUTHERN THURSTON COUNTIES-MIDDLE
CHEHALIS RIVER VALLEY-NORTHERN HOOD CANAL-OLYMPIA AND
SOUTHERN PUGET SOUND-SOUTHERN HOOD CANAL.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM PDT THURSDAY 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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