419
FXUS66 KSEW 102201
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
301 PM PDT THU JUL 10 2025
SYNOPSIS
HIGH PRESSURE RETURNING TO THE REGION WILL RESULT IN
AN EXTENDED PERIOD OF WARM AND DRY CONDITIONS THAT WILL PERSIST WELL
INTO NEXT WEEK. TEMPERATURES ARE EXPECTED TO PEAK TUESDAY INTO
WEDNESDAY, WHERE TEMPERATURES COULD REACH THE LOW TO MID 90S FOR
MANY AREAS.
SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/
AS EXPECTED, THE
DEEPER MARINE LAYER TODAY HAS HELPED THE STRATUS LINGER WELL
INTO THE AFTERNOON. CEILINGS HAVE BEEN LIFTING AND STARTING TO
SCATTER ALL ALONG THE I-5 CORRIDOR WITH SOME BLUE SKY LEADING
INTO THE EVENING HOURS FOR MOST AREAS OUTSIDE OF THE COAST.
HIGH TEMPERATURES ALONG THE COAST TODAY WILL REMAIN IN THE MID
60S, WITH TEMPERATURES IN THE LOWER 70S THROUGH THE INLAND
AREAS.
THE OFFSHORE UPPER LEVEL RIDGE WILL TIP INTO THE PACIFIC
NORTHWEST FRIDAY WITH LESS MORNING STRATUS AND A BUMP TO
TEMPERATURES - BACK INTO THE LOWER TO MID 80S ACROSS MUCH OF
THE INTERIOR LOWLANDS. LINGERING, ALBEIT WEAKER ONSHORE FLOW
WILL MAINTAIN CLOUDY SKIES ALONG THE PACIFIC COAST WITH MOSTLY
CLEAR AND DRY CONDITIONS ELSEWHERE. A WEAK UPPER LEVEL WAVE
RIDING THE RIDGE SATURDAY WILL BRING A FEW EXTRA CLOUDS HIGH
CLOUDS ESPECIALLY ALONG THE NORTHERN BORDER, BUT ULTIMATELY VERY
SIMILAR CONDITIONS - WARM AND DRY WITH HIGHS IN THE 80S OVER THE
INTERIOR AND NEAR 70 ALONG THE COAST.
LONG TERM /SUNDAY THROUGH THURSDAY/
CONDITIONS ON SUNDAY INTO
MONDAY LOOK TO BEGIN TRENDING WARMER AS HIGH PRESSURE CONTINUES
TO BUILD OFFSHORE, WITH HIGH TEMPERATURES WORKING MORE INTO THE
UPPER 80S. SOME OF THE ENSEMBLES DO SHOW PERHAPS A BIT OF A
BRIEF PAUSE TO THE WARMING TREND MONDAY - WITH HIGHS STILL IN
THE MID TO PERHAPS UPPER 80S. NBM CONTINUES TO HIGHLIGHT
TEMPERATURES PEAKING TUESDAY INTO WEDNESDAY. FOR TUESDAY
WIDESPREAD AREAS OVER THE INTERIOR SOUTH OF PUGET SOUND INTO
THE CASCADE VALLEYS AND FOOTHILLS HAVING AN 80-85% CHANCE OF
HIGH TEMPERATURES AT OR ABOVE 90. THIS WILL EXPAND WEDNESDAY -
EXTENDING NORTHWARD THROUGH THE KITSAP PENINSULA, WESTERN KING
AND SNOHOMISH COUNTIES. IN ADDITION TO THE VERY WARM DAYTIME
TEMPERATURES, OVERNIGHT LOWS IN THE METRO AREA WILL START TO
STRUGGLE TO COOL BELOW 60 DEGREES MONDAY NIGHT INTO TUESDAY
MORNING. THIS WILL BROADEN TO MOST OF THE INTERIOR OVERNIGHT
TUESDAY NIGHT AND AGAIN WEDNESDAY NIGHT. THE OVERALL WARMING
TREND WILL RESULT IN WIDESPREAD MODERATE (ORANGE) HEATRISK TO
WESTERN WASHINGTON BY TUESDAY WITH LOCAL AREAS OF MAJOR (RED)
HEATRISK. SOME DEGREE OF COOLING IS NOW INDICATED FOR THURSDAY -
BUT TEMPERATURES WILL LIKELY REMAIN IN THE 80S OVER MUCH OF THE
INTERIOR - STILL WELL ABOVE NORMAL.
AVIATION
FLOW TURNING NORTHWESTERLY THIS AFTERNOON AS AN UPPER-
RIDGE BUILDS OFFSHORE. SHOWERS FROM EARLIER ARE DRYING OUT AND LOW
STRATUS IS RISING AND GRADUALLY CLEARING AS A RESULT. MOSTLY VFR
OBSERVED SO FAR BUT ISOLATED MVFR/IFR REMAINS (KHQM). FOR TONIGHT,
STRATUS WILL BE MOSTLY CONFINED TO THE COAST, SW INTERIOR AND BITS
HUGGING THE CASCADES. KHQM HAS A 70-80% CHANCE OF CIGS AROUND IFR TO
LIFR OVERNIGHT INTO FRIDAY MORNING WITH MIST POSSIBLY LIMITING
VISIBILITY. STRATUS WILL RETREAT TO THE IMMEDIATE COASTLINE BY 18Z
FRIDAY WITH VFR FOR ALL INTERIOR TERMINALS EXPECTED. WINDS BECOMING
NW THIS EVENING AND MAINTAIN A NORTHERLY COMPONENT INTO FRIDAY
BETWEEN 5-10 KT (LIGHTER OVERNIGHT).
KSEA...VFR NOW OBSERVED THIS AFTERNOON AND FAVORED TO REMAIN
THROUGHOUT THE TAF PERIOD. THERE'S A 20% CHANCE OF MVFR CIGS
BETWEEN 12-16Z FRIDAY DUE TO PATCHY MARINE STRATUS. SOUTHWEST
WINDS TURNING NORTHWESTERLY BY 00Z FRIDAY WITH NW WINDS
PERSISTING INTO THE DAY ON FRIDAY ON BETWEEN 5-10 KT.
MCMILLIAN
MARINE
FLOW TURNING NW OVER THE COASTAL WATERS THIS EVENING AS A
SURFACE HIGH SITS WELL OFFSHORE. BENIGN SEAS TONIGHT BUT A SHALLOW
MARINE LAYER COULD LEAD TO PATCHY FOG OVER AREA WATERS INTO FRIDAY
MORNING. FOR FRIDAY, ONSHORE FLOW LOOKS TO INCREASE AND BECOME
STRONG. SCA WINDS ARE PROBABLE FOR THE CENTRAL AND EASTERN STRAIT OF
JUAN DE FUCA ON FRIDAY EVENING INTO EARLY SATURDAY MORNING. DIURNAL
PUSHES ARE FAVORED THROUGHOUT THE STRAIT THIS WEEKEND AND COULD
REACH ADVISORY LEVELS. A TROUGH PASSING TO THE NORTH EARLY NEXT WEEK
MAY PRODUCE GUSTY WINDS IN THE OUTER COASTAL WATERS, ALONG WITH
STEEPER SEAS.
SEAS WILL RANGE 3-5 FEET TODAY THROUGH FRIDAY, INCREASING TO 6 TO 8
FEET OVER THE WEEKEND, COUPLE SPOTS FURTHER OFFSHORE MAY SEE 10 FEET
SEAS INTO EARLY NEXT WEEK.
MCMILLIAN
FIRE WEATHER
SKIES WILL BEGIN TO CLEAR OUT TONIGHT AS HIGH
PRESSURE BEGINS TO BUILD OVER THE REGION, SIGNALING THE BEGINNING OF
A PROLONGED WARMING AND DRYING TREND FROM FRIDAY THROUGH NEXT WEEK.
FRIDAY WILL BE NOTABLY DRY, WITH RH VALUES DROPPING BACK INTO THE 25-
35% RANGE OVER THE MOUNTAINS AS WELL AS THE INTERIOR LOWLANDS SOUTH
OF THE PUGET SOUND. MORE ROBUST ONSHORE FLOW THIS WEEKEND WILL HELP
USHER IN MORE MOIST AIR WITH MIN RHS BACK INTO THE 30S AND 40S,
DESPITE HIGH TEMPERATURES REMAINING IN THE 80S.
WHILE THERE IS STILL SOME MODEL DISCREPANCY OVER HOW WARM AND DRY WE
GET NEXT WEEK, THERE IS CONSENSUS THAT THE WARM AND DRY WILL
CONTINUE INTO THE MIDDLE OF NEXT WEEK, WITH THE FLOW SWITCHING TO
OFFSHORE BY TUESDAY AS A THERMAL TROUGH BEGINS TO BUILD ALONG THE
COAST. FIRE WEATHER CONCERNS WILL BE ELEVATED BEGINNING TUESDAY AS
MINIMUM RH VALUES LOOK TO DROP INTO THE 20S ACROSS MUCH OF THE
CASCADES AND THE INTERIOR LOWLANDS SOUTH OF SEATTLE. THERE MAY ALSO
BE SOME LOCALLY BREEZY WINDS THROUGH THE CASCADE GAPS. THIS PATTER
WILL CONTINUE TO BE CLOSELY MONITORED AS WE APPROACH NEXT.
62
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
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