485
FXUS66 KSEW 040346
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
846 PM PDT FRI OCT 3 2025
UPDATE
SATELLITE IMAGERY SHOWS CLOUDY SKIES OVER WESTERN
WASHINGTON THIS EVENING. A FEW PRECIPITATION ECHOES ON THE DOPPLER
RADAR BUT WITH NO REPORTS OF RAIN IN THE OBSERVATIONS AND CLOUD
CEILINGS ABOVE 6000 FEET EXPECT MOST OF THE PRECIPITATION IS NOT
REACHING THE GROUND. TEMPERATURES AT 8 PM/03Z WERE IN THE 50S AND
LOWER 60S.
WEAK FRONTAL SYSTEM MOVING THROUGH WESTERN WASHINGTON OVERNIGHT.
NOT MUCH PRECIPITATION WITH THE SYSTEM. A FEW SHOWERS OVER CENTRAL
AND NORTHERN VANCOUVER ISLAND ALL THAT HAS BEEN OBSERVED SO FAR.
ISOLATED SHOWERS BEHIND THE FRONT SATURDAY DRYING UP AS THE DAY
WEARS ON WITH THE FLOW ALOFT BECOMING NORTHERLY IN RESPONSE TO A
BUILDING UPPER LEVEL RIDGE OFFSHORE. POPS COULD BE A LITTLE HIGH
OVERNIGHT INTO SATURDAY. WILL LET OVERNIGHT SHIFT SEE FULL MODEL
RUN FOR POSSIBLE LOWERING OF POPS SATURDAY. COOLER MORNINGS AHEAD
WITH THE COLDER LOCATIONS GETTING INTO THE UPPER 30S MONDAY
MORNING. FELTON
PREV DISCUSSION
/ISSUED 307 PM PDT FRI OCT 3 2025/
SYNOPSIS
LIGHT SHOWERS WILL MAKE A RETURN TONIGHT INTO
SATURDAY BEFORE HIGH PRESSURE BRINGS MORE WARMING AND DRYING TO
WESTERN WASHINGTON THROUGH THE MIDDLE OF NEXT WEEK. CHANCES FOR
MORE WIDESPREAD PRECIPITATION INCREASE INTO NEXT WEEKEND.
SHORT TERM /TONIGHT THROUGH MONDAY/
A WEAK FRONTAL SYSTEM
WILL CROSS THE REGION THIS EVENING, SPREADING LIGHT SHOWERS INLAND
INTO THE EARLY MORNING HOURS SATURDAY. NORTHERLY FLOW WILL
DEVELOP BEHIND, BRINGING TEMPERATURES DOWN A FEW DEGREES BELOW
NORMAL. ISOLATED SHOWER ACTIVITY MAY LINGER INTO SATURDAY
AFTERNOON, BUT MUCH OF THE REGION WILL SEE LITTLE MORE THAN CLOUDY
SKIES THROUGH THE REMAINDER OF THE DAY.
BY SUNDAY, AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL AMPLIFY OVER
THE NORTHERN PACIFIC AND START TO BUILD INLAND TOWARDS THE PACIFIC
NORTHWEST. THIS WILL KICK OFF A WARMING AND DRYING TREND INTO
MONDAY, WITH MILD TEMPERATURES AND MOSTLY CLEAR SKIES ON SUNDAY
AND MONDAY.
LONG TERM /TUESDAY THROUGH FRIDAY/
MODELS SHOW GOOD AGREEMENT
OVER THE UPPER RIDGE AXIS SHIFTING INLAND ON TUESDAY, MAINTAINING
WARM AND DRY CONDITIONS ACROSS WESTERN WASHINGTON. TEMPERATURES
ARE ON TRACK TO REACH THE LOW TO MID 70S ACROSS THE INTERIOR
LOWLANDS, ROUGHLY 5 TO 10 DEGREES ABOVE NORMAL FOR EARLY OCTOBER.
BY THE MIDDLE OF NEXT WEEK, FORECAST MODELS BEGIN TO SHOW
DIFFERENT SOLUTIONS. A CUTOFF LOW IS EXPECTED TO DEVELOP ALONG THE
WESTERN US COAST, BUT A LARGE DEGREE OF UNCERTAINTY REMAINS OVER
THE TRACK OF THIS LOW PRESSURE SYSTEM. WHILE SOME MODELS SHOW THE
LOW MOVING SOUTH AND STALLING OFFSHORE, KEEPING WESTERN WASHINGTON
DRY, OTHER MODELS BRING WIDESPREAD PRECIPITATION INTO THE PACIFIC
NORTHWEST AS EARLY AS WEDNESDAY. A CHANCE OF PRECIPITATION IS
MAINTAINED THROUGH THE EXTENDED FORECAST, THOUGH SIGNIFICANT
RAINFALL IS NOT EXPECTED ACROSS WESTERN WASHINGTON AT THIS TIME.
15
AVIATION
A WEAKENING COLD FRONT IS BEGINNING TO APPROACH THE AREA
FROM THE NORTHWEST. THIS HAS BROUGHT IN MID TO HIGH LEVEL CLOUDS
THIS EVENING. CEILINGS WILL THEN SLOWLY LOWER OVERNIGHT, BECOMING
MOSTLY MVFR TO IFR AREA-WIDE BY SATURDAY MORNING. GIVEN THE
SUFFICIENT MOISTURE IN THE LOW-LEVELS, MODELS ARE INDICATING THAT
LOCALLY LOWER CEILINGS TO LIFR AND AREAS OF FOG WILL BE A THREAT
ONCE AGAIN BY TOMORROW MORNING. EXPECT A SIMILAR TREND ON SATURDAY
MORNING, A SLOW RISE IN CEILINGS, LIFTING AND SCATTERING THROUGH
MUCH OF THE DAY WITH A RETURN TO VFR CONDITIONS NOT EXPECTED UNTIL
SATURDAY AFTERNOON (21Z SAT OR SHORTLY THEREAFTER). WINDS LOOK TO
REMAIN LIGHT OVERNIGHT TONIGHT, BECOMING NORTHERLY AROUND 6 KT OR
LESS ON SATURDAY.
KSEA...EXPECT CLOUDS TO MOVE IN THROUGHOUT THE REST OF THE NIGHT AND
SLOWLY LOWER ALL THE WAY DOWN THE IFR (30-50% CHC.) OR LIFR (25-35%
CHC.) BY SATURDAY MORNING. AREAS OF FOG ARE POSSIBLE ONCE AGAIN WITH
LIMITATIONS TO VISIBILITY AFTER 06-09Z. OPTED FOR A PROB30 FOR LIGHT
SHOWERS BETWEEN 08-12Z. THE LOWEST CONDITIONS WILL PERSIST THROUGH
AROUND 16-18Z BEFORE CLOUDS AND FOG SLOWLY RISE AND SCATTER THROUGH
THE REST OF THE MORNING. VFR CONDITIONS WILL BE SLOW TO RETURN
SATURDAY AFTERNOON. WIND SPEEDS REMAIN 6 KT OR LESS THROUGH THE
PERIOD. SW WINDS WILL SLOWLY VEER TO BECOME N/NE THEN LIGHT AND
VARIABLE TONIGHT THEN REMAINING N TOMORROW.
62/21
MARINE
A WEAKENING LOW PRESSURE SYSTEM CURRENTLY CENTERED
OFFSHORE OF SOUTHWEST WA WILL CONTINUE TO DISSIPATE AS IT MOVES
SOUTHWARD. ANOTHER FRONT IS BEGINNING TO MOVE IN FROM BRITISH
COLUMBIA BUT IS QUICKLY WEAKENING AS IT DOES SO, PASSING OVER THE
AREA TONIGHT INTO SATURDAY MORNING. HIGH PRESSURE WILL QUICKLY
TAKE ITS PLACE OVER THE COASTAL WATERS SATURDAY NIGHT THROUGH THE
FIRST PART OF NEXT WEEK. TROUGHING ALONG THE COASTLINE WILL HELP
TURN THE WINDS OFFSHORE, WITH NORTH TO NORTHEAST WINDS OVER THE
COASTAL WATERS. THROUGH THERE REMAINS SOME UNCERTAINTY, A FRONTAL
SYSTEM LOOKS TO APPROACH THE COASTAL WATERS BY TUESDAY NIGHT,
BRINGING WITH IT INCREASING NORTHWESTERLY WINDS THAT HAVE A 30-50%
CHANCE OF EXCEEDING 21 KT.
SEAS WILL REMAIN AROUND 4-6 FT THROUGH THE WEEKEND. SEAS WILL
BUILD TUESDAY TO 6-8 FT.
62
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
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