537
FXUS66 KSEW 092228
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
328 PM PDT MON JUN 9 2025
SYNOPSIS
AN UPPER LEVEL RIDGE OVER WASHINGTON WILL PRODUCE ONE
MORE DAY OF HOT TEMPERATURES TODAY. THE WARMEST AREAS WILL BE IN
THE SEATTLE METRO AND AREAS SOUTH, AND MOST CASCADE VALLEYS WITH
HIGHS IN THE UPPER 80S TO LOW 90S. THE RIDGE WILL WEAKEN TONIGHT
ALLOWING FOR SOME ONSHORE COOLING TONIGHT. ADDITIONAL COOLING IS
EXPECTED MID WEEK AS A TROUGH MOVES INLAND, BRINGING TEMPERATURES
BELOW NORMAL FOR THIS TIME IN JUNE. SHOWERS WILL BE POSSIBLE IN
THE CASCADES THURSDAY THROUGH NEXT WEEKEND, AND ALONG THE COAST
LATE NEXT WEEKEND.
SHORT TERM /TONIGHT THROUGH THURSDAY/
AN UPPER LEVEL RIDGE
REMAINS PLANTED OVER MUCH OF WA TODAY, WITH THE AXIS OVER EAST WA
THIS AFTERNOON. DOWN AT THE SURFACE A SURFACE LOW/COLD FRONT TO
THE EAST OF THE CASCADES HAS HELPED RETURN SOME ONSHORE FLOW TODAY
WITH BUILDING HEIGHTS TO THE WEST. AS A RESULT, TEMPERATURES WILL
BE A BIT COOLER ALONG THE COAST TODAY.
AS OF JUST PAST NOON, TEMPERATURES VARY GREATLY ACROSS WESTERN WA
UNDER CLEAR SKIES AND LIGHT NORTHWEST WINDS. COOLEST TEMPERATURES
ARE ALONG THE COAST (CURRENTLY IN THE 60S WITH HIGHS TOPPING OUT
IN THE MID 60S). UP NORTH IN THE SAN JUANS/NORTH OF EVERETT (ALONG
THE COAST), HIGHS WILL TOP OUT 75-80 TODAY. IN THE HEAT ADVISORY
AREAS (SEATTLE METRO, KITSAP, SOUTH INTERIOR, CASCADE VALLEYS),
TEMPERATURES HAVE ALREADY REACHED THE UPPER 70S TO MID 80S, AND
ARE EXPECTED TO CONTINUE TO CLIMB THIS AFTERNOON TO THE MID 80S TO
LOW 90S. THERE REMAINS A MODERATE HEATRISK IN THESE AREAS FOR
TODAY, SO WILL CONTINUE THE HEAT ADVISORY HEADLINE THROUGH 10 PM
PDT TONIGHT.
ONSHORE FLOW IS EXPECTED TO INCREASE TONIGHT AS THE HEIGHTS BUILD
OFFSHORE DOWN AT THE SURFACE (AND AS THE RIDGE ABOVE BEGINS TO
FLATTEN AND MOVE EAST). AS A RESULT, LOWS TONIGHT WILL BE MUCH
MORE COMFORTABLE (LOW TO UPPER 50S, WITH THE WARMEST LOWS IN THE
SEATTLE METRO). TUESDAY WILL STILL BE WARM BUT IS NOT EXPECTED TO
BE AS HOT - 50S AND 60S ALONG THE COAST, AND MID 70S TO LOW 80S
FURTHER INLAND. A FEW MORE CLOUDS WILL BE PRESENT TOO (ESPECIALLY
ALONG THE COAST AND IN THE CASCADES). LOWS WILL DROP A FEW MORE
DEGREES TUESDAY NIGHT (COMPARED TO TONIGHT).
THE PATTERN SWITCHES MORE TO TROUGH/COOLER WEATHER STARTING
WEDNESDAY INTO MUCH OF THE EXTENDED OUTLOOK. THE MAIN IMPACT WITH
THIS PATTERN CHANGE IS THAT TEMPERATURES WILL DROP TO AROUND OR
BELOW NORMAL ACROSS THE REGION. THE HIGHS WEDNESDAY WILL REMAIN
BELOW 80 (LOT MORE HIGHS IN THE MID TO UPPER 70S ALONG THE I-5
CORRIDOR). BY THURSDAY, THIS DROPS INTO UPPER 60S TO LOW 70S. LOWS
WILL DROP AS WELL, DOWN TO THE UPPER 40S TO LOW 50S REGIONWIDE.
AS FAR AS MOISTURE GOES, IT CONTINUES TO REMAIN DRY THROUGH THE
REGION UP THROUGH THURSDAY WITH CLOUDS INCREASING EACH DAY UP TO
THURSDAY (MOST CLOUDS WILL BE OVERNIGHT/MORNING WITH THE MARINE
PUSHES). THE FIRST CHANCE OF SHOWERS (IN A WHILE) WILL RETURN FOR
THE CASCADES THURSDAY AFTERNOON (NORTH OF I-90).
LONG TERM /FRIDAY THROUGH MONDAY/
MODELS HAVE GOOD AGREEMENT IN
THE TROUGH/COOLER PATTERN CONTINUING THROUGH NEXT WEEKEND.
TEMPERATURES WILL REMAIN AROUND NORMAL WITH HIGHS RANGING FROM THE
60S TO LOW 70S EACH DAY IN THE EXTENDED, WITH LOWS IN THE 40S TO
LOW 50S. CLOUDS FROM THURSDAY WILL CONTINUE INTO FRIDAY WITH MORE
OF A MIX OF CLOUDS AND SUN FOR NEXT WEEKEND. SHOWER CHANCES FOR
THE CASCADES FROM THURSDAY WILL LINGER INTO FRIDAY, WITH
ADDITIONAL SHOWERS POSSIBLE ACROSS THE REGION LATE NEXT
WEEKEND/EARLY NEXT WEEK.
HPR
AVIATION
VFR CONDITIONS EXPECTED TO PREVAIL THROUGHOUT THE TAF
PERIOD, WITH THE EXCEPTION OF TERMINALS ALONG THE COAST (KHQM).
CLOUD COVER WILL INCREASE ALONG THE COAST LATE TONIGHT INTO THE
OVERNIGHT HOURS, BRINGING CEILINGS DOWN TO MVFR AND POTENTIALLY IFR
(30% CHANCE). NORTHERLY FLOW ALONG THE INTERIOR TERMINALS 6-9 KT,
EASING OVERNIGHT. SURFACE FLOW WILL MORE WESTERLY ALONG THE COAST
WITH WINDS 10-14 KT, EASING OVERNIGHT TO 5-7 KT.
KSEA...VFR EXPECTED EXPECTED TO PERSIST FOR THE TAF PERIOD.
GENERALLY NORTHERLY/NORTHWESTERLY SURFACE FLOW WITH SPEEDS OF 6-8
KT, EASING OVERNIGHT TO 3-5 KT.
29
MARINE
HIGH PRESSURE OVER THE WATERS WILL CONTINUE TO WEAKEN
OVER THE NEXT COUPLE DAYS. NORTHWESTERLY SURFACE FLOW EXPECTED TO
PERSIST INTO THE WEEKEND. STRONGER NORTHWESTERLY WINDS AND WAVES OF
9 TO 13 FT FOR THE OUTER COASTAL WATERS WILL KEEP A SMALL CRAFT
ADVISORY IN EFFECT INTO AT LEAST TUESDAY NIGHT. SEAS WILL GRADUALLY
DECREASE ON WEDNESDAY BUT MAY HAVE TO EXTEND THE SMALL CRAFT INTO
WEDNESDAY AS WAVES LOOK TO HOVER AROUND 10 FT FOR PORTIONS OF THE
OUTER COASTAL WATERS. SEAS LOOK TO REBUILD ABOVE 10 FT LATE IN THE
WEEK.
ADDITIONAL HEADLINES ARE POSSIBLE EACH EVENING STARTING ON WEDNESDAY
FOR THE CENTRAL AND EASTERN PORTIONS OF THE STRAIT OF JUAN DE FUCA
DUE TO INCREASED WEST WINDS. THE STRONGEST PUSH OF WINDS WILL BE
THURSDAY, WHERE WIND GUSTS MAY APPROACH HIGH-END SMALL CRAFT
CRITERIA AND POTENTIALLY LOW-END GALE CRITERIA. AT THIS TIME,
GUIDANCE IS NOT GIVING A STRONG SIGNAL ON REACHING GALE CRITERIA AS
PROBABILITIES FOR REACHING 34 KT OR GREATER ARE AROUND 10-15%.
29
FIRE WEATHER
WARM AND DRY CONDITIONS CONTINUE MONDAY AS AN
UPPER LEVEL RIDGE MOVES ACROSS WESTERN WASHINGTON. THIS WILL
ELEVATE FIRE WEATHER CONCERNS TODAY AS MINIMUM RH VALUES WILL
LIKELY REACH AS LOW AS 30% OVER THE MOUNTAINS WITH SLIGHTLY
HIGHER VALUES THROUGH THE INTERIOR. WHILE LIVE FUELS ARE STILL WET
ENOUGH TO CURB FIRE SPREAD, DEAD FUELS REMAIN VERY DRY. IN
ADDITION, SNOWPACK IS BELOW NORMAL AND SOME LOCATIONS ARE
EXPERIENCING DROUGHT CONDITIONS. WINDS REMAIN LIGHT ENOUGH INTO
MONDAY SUCH THAT CRITICAL FIRE WEATHER CONDITIONS ARE NOT EXPECTED
BUT THE AREA IS DRYING OUT FAST. MOIST ONSHORE FLOW WILL RETURN
MONDAY NIGHT INTO TUESDAY.
SEW WATCHES/WARNINGS/ADVISORIES
WA...HEAT ADVISORY UNTIL 10 PM PDT THIS EVENING FOR CITY OF SEATTLE-
DOWNTOWN EVERETT / MARYSVILLE AREA-EASTERN KITSAP COUNTY-
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-
LOWLANDS OF LEWIS AND SOUTHERN THURSTON COUNTIES-LOWLANDS
OF PIERCE AND SOUTHERN KING COUNTIES-NORTHERN HOOD CANAL-
OLYMPIA AND SOUTHERN PUGET SOUND-SHORELINE / LYNNWOOD /
SOUTH EVERETT AREA-SOUTHERN HOOD CANAL.
PZ...SMALL CRAFT ADVISORY UNTIL 11 PM PDT TUESDAY 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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