137
FXUS66 KSEW 100352
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
852 PM PDT TUE SEP 9 2025
SYNOPSIS
AN UPPER LOW SOUTH OF THE AREA WILL CONTINUE TO
WEAKEN AND SHIFT EASTWARD. THIS WILL SPREAD MOISTURE INTO THE
REGION, WITH SHOWERS AND ISOLATED THUNDERSTORMS DEVELOPING NEAR
THE CASCADES AND MOVING INTO THE REGION. WEAK HIGH PRESSURE
THURSDAY AND FRIDAY WILL BRING SOME DRIER CONDITIONS, BUT
ANOTHER DISTURBANCE BRINGS A RETURN OF RAIN TO THE REGION LATE
IN THE WEEKEND.
SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/
FORECAST ON TRACK
THIS EVENING. NO UPDATES TO THE FORECAST. SHOWERS AND ISOLATED
THUNDERSTORMS OVER THE CASCADES EARLIER THIS EVENING HAVE ALMOST
COMPLETELY DISSIPATED WITH THE END OF THE DAYTIME HEATING. THE
CHANCE FOR LATE DAY SHOWERS WITH ISOLATED THUNDERSTORMS WILL
REMAIN INTO WEDNESDAY WITH LESS COVERAGE. CONVECTION MOSTLY
CONFINED TO JUST THE HIGH CASCADES AS THE BEST SUPPORT CONTINUES
TO SHIFT EASTWARD. DAYTIME HIGHS WEDNESDAY ARE NOT EXPECTED TO
CHANGE VERY MUCH, WITH THE INTERIOR LOWLANDS GENERALLY IN THE
LOWER TO MID 70S. THIS FALLS RIGHT AROUND NORMAL VALUES FOR THIS
TIME OF YEAR.
UPPER LEVEL LOW CENTERED TO THE SOUTH OF THE AREA SLOW TO MOVE
EAST WEDNESDAY NIGHT INTO THURSDAY KEEPING A SLIGHT CHANCE OF
SHOWERS IN THE FORECAST. TEMPERATURES REMAINING NEAR NORMAL.
LONG TERM /FRIDAY THROUGH MONDAY/
MODELS REMAIN WITH OUT
CONSENSUS WITH REGARDS TO NEXT INCOMING SYSTEM. WHILE MOST SOLUTIONS
KEEP CONDITIONS DRY FRIDAY AND EVEN INTO SATURDAY MORNING, VARIANCES
EMERGE BY SATURDAY EVENING WHERE A FEW ENSEMBLE MEMBERS PROVE TO BE
A LITTLE AGRESSIVE IN INTRODUCING POPS. ADDITIONAL MEMBERS LEANING
TO AN OVERNIGHT SATURDAY SOLUTION BUT THE SLIM MAJORITY SEEM TO BE
CONVERGING AROUND SUNDAY MORNING, HOWEVER EVEN THEN DIFFERENCES OF
OPINION ON THE TRACK OF THE INCOMING LOW WILL RESULT IN A WIDE ARRAY
OF EXPECTED PRECIP AMOUNTS. THUS, WHILE POPS DO RE-ENTER THE
FORECAST SATURDAY THROUGH THE REMAINDER OF THE LONG TERM, MUSTERING
ANYTHING MORE THAN A 50 PCT CHANCE COULD BE A BIT OF A STRETCH. THE
ACTIVE WEATHER WILL KEEP TEMPERATURES SEASONABLE, WITH INTERIOR
LOWLANDS SEEING HIGHS IN THE LOWER 70S AND OVERNIGHT LOWS IN
THE MID TO UPPER 50S.
AVIATION
VFR CONDITIONS ACROSS MUCH OF WESTERN WASHINGTON,
EXCEPT ALONG THE COAST WHERE STRATUS IS BEGINNING TO REDEVELOP AND
PUSH INLAND. STRATUS WILL PUSH ALL THE WAY INLAND ACROSS ALL THE
AREA TERMINALS, BRINGING IFR TO LIFR CEILINGS AND PATCHY FOG ACROSS
THE WESTERN WASHINGTON LOWLANDS BEFORE CEILINGS RISE AND SCATTER
LATE WEDNESDAY MORNING INTO THE AFTERNOON. WINDS REMAIN LIGHT
NORTH/NORTHWESTERLY, 5 KT OR LESS FOR MOST OF THE AREA.
KSEA...VFR WITH HIGH CLOUDS LEAVING THE AREA. MVFR TO IFR CONDITIONS
WILL LIKELY RETURN AROUND 11Z-14Z WEDNESDAY MORNING, SCATTERING OUT
AROUND 18Z-20Z FOR A RETURN TO VFR CONDITIONS WITH SCATTERED CLOUDS
WEDNESDAY AFTERNOON. AN HOUR OR TWO OF LIFR CIGS FROM 14-16Z WILL BE
POSSIBLE (25% CHANCE). NORTHWEST WINDS UP TO 5 KT WILL BECOME LIGHT
AND VARIABLE OVERNIGHT, WITH WINDS AGAIN NORTHWESTERLY 6-7 KT OR
LESS DURING THE DAY WEDNESDAY.
62
MARINE
WEAK LOW PRESSURE OFFSHORE TODAY WILL SHIFT INLAND ON
WEDNESDAY WITH A STRONGER ONSHORE PUSH DOWN THE STRAIT THURSDAY
NIGHT - SMALL CRAFT ADVISORY WINDS ARE POSSIBLE. ONSHORE FLOW WILL
ALSO MAINTAIN PERIODS OF PATCHY FOG OVER THE COASTAL WATERS AND
THROUGH THE STRAIT OF JUAN DE FUCA THROUGH THE MIDDLE OF THE WEEK.
HIGH PRESSURE WILL DEVELOP OFFSHORE ON FRIDAY. A WEAK FRONT WILL
DISSIPATE OVER THE COASTAL WATERS THIS WEEKEND.
SEAS WILL GENERALLY REMAIN BETWEEN 4 AND 7 FEET INTO EARLY NEXT WEEK.
15
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
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