107
FXUS66 KSEW 051058
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
358 AM PDT SUN OCT 5 2025
SYNOPSIS
HIGH PRESSURES WILL BRING DRY AND MILD WEATHER THROUGH
EARLY THIS WEEK. EXPECT COOLER AND CLOUDIER WEATHER BY MIDWEEK
WITH STRONGER ONSHORE FLOW. LOW PRESSURE WILL SPIN OFFSHORE OVER
THE LATTER HALF OF THE WEEK THEN SHIFT INLAND OVER THE WEEKEND.
SHORT TERM /TODAY THROUGH TUESDAY/
DRY, NORTH, FLOW PREVAILS
ACROSS WESTERN WA TODAY WITH A RIDGE OFFSHORE. WE MAY SEE PATCHY
LOW CLOUDS AND FOG OVER THE SOUTH SOUND AND COAST, OTHERWISE
EXPECT CLEAR SKIES. TEMPERATURE TRENDS WILL TRACK CLOSE TO AVERAGE
AND IN THE MID 60S.
HIGH PRESSURE SHIFTS INLAND ON MONDAY WITH WINDS TURNING LIGHT
OFFSHORE. TEMPERATURES WILL BE SLIGHTLY WARMER WITH HIGHS
REACHING THE LOWER 70S.
THE RIDGE FLATTENS OVER THE REGION ON TUESDAY BUT THE LOW LEVEL
AIR MASS WILL REMAIN WARM/MILD WITH ONGOING OFFSHORE FLOW. THE
CASCADE FOOTHILLS AND VALLEYS WILL REACH THE MID 70S FOR HIGHS
WITH MID 60S TO LOWER 70S ELSEWHERE. THE FLOW WILL TURN ONSHORE
TUESDAY NIGHT AS A WEAK FRONT MOVES THROUGH. WE'RE NOT SEEING TOO
MUCH PRECIP WITH THIS FRONT WITH JUST A TRACE TO A FEW HUNDREDTHS
IF ANYTHING. 33
LONG TERM /WEDNESDAY THROUGH SATURDAY/
WITH A FLIP TO ONSHORE
FLOW, EXPECT COOLER AND CLOUDIER CONDITIONS MOVING INTO
WEDNESDAY. THEREAFTER, LOW PRESSURE WILL SPIN OFFSHORE THURSDAY
AND FRIDAY WITH GENERALLY MILD CONDITIONS. SOME MOISTURE MAY
ADVECT NORTH INTO WESTERN WA FOR A CHANCE OF RAIN, ALTHOUGH
ENSEMBLE QPF IS LIGHT. RAIN CHANCES INCREASE OVER THE WEEKEND AS
THE LOW EVENTUALLY SHIFTS INLAND. 33
AVIATION
A MIX OF CEILINGS AND VISIBILITIES EARLY THIS MORNING
ACROSS WESTERN WASHINGTON TERMINALS. A LOW CLOUD DECK OVER EASTERN
PUGET SOUND IS BRINGING LOW CEILINGS TO TERMINALS IN THE VICINITY
RANGING FROM MVFR TO LIFR. LATEST METAR OBS SHOW FOG HAS DEVELOPED
OVER PWT AND WITH OBS SHOWING RELATIVE HUMIDITY VALUES IN THE 90S,
FOG IS POSSIBLE FOR TERMINALS ALONG THE COAST, SOUTHERN INTERIOR,
AND NORTHERN INTERIOR. CONDITIONS SHOULD IMPROVE IN THE AFTERNOON TO
VFR AFTER 18Z-21Z FOR ALL TERMINALS AND SHOULD GENERALLY PERSIST
THROUGH THE END OF THE TAF PERIOD. WINDS WILL INCREASE THIS MORNING
AFTER 11Z-13Z THROUGH THE EVENING; WINDS WILL GENERALLY BE N/NE AT 8-
12 KT. WINDS WILL EASE SUNDAY NIGHT INTO MONDAY'S OVERNIGHT HOURS.
KSEA...A LOW CLOUD DECK OVER PUGET SOUND BRINGS MVFR CEILINGS TO THE
TERMINAL EARLY THIS MORNING, WITH IMPROVEMENT EXPECTED AFTER 18-19Z.
WINDS WILL INCREASE OUT OF THE N/NE TO 8-11 KT TODAY, LIKELY
OVERLAPPING LOW CEILINGS BETWEEN 11Z-19Z. WINDS WILL EASE SUNDAY
NIGHT INTO EARLY MONDAY MORNING TO AROUND 6-7 KT. GUIDANCE DOES
SUGGEST THAT MVFR CEILINGS MAY RETURN MONDAY MORNING (25-35% CHANCE).
29
MARINE
HIGH PRESSURE OVER THE COASTAL WATERS, WITH A
THERMAL THROUGH BUILDING NORTHWARD ALONG THE COAST TODAY THROUGH
TUESDAY. AS A RESULT, SURFACE FLOW WILL TURN OFFSHORE ACROSS AREA
WATERS AT TIMES. WINDS IN THE CENTRAL AND EAST PORTIONS OF THE
STRAIT OF JUAN DE FUCA WILL INCREASE EARLY THIS MORNING AND MAY
APPROACH SMALL CRAFT CRITERIA. HOWEVER, HELD OFF ON ISSUING A SMALL
CRAFT ADVISORY AS PROBABILITIES WERE NOT VERY FAVORABLE.
PROBABILITIES OF EXCEEDING 21 KT IN THE CENTRAL STRAIT ARE 10-25%
FOR SUSTAINED AND 20-40% FOR GUSTS. AS FOR THE EASTERN STRAIT,
PROBABILITIES OF EXCEEDING 21 KT ARE 10-15% FOR SUSTAINED AND 40-60%
FOR GUSTS. ALTHOUGH THESE PROBABILITIES DEPICT LOW TO MEDIUM
CHANCES, AN OCCASIONAL GUST EXCEEDING 21 KT CANNOT BE RULED OUT.
A WEAKENING FRONTAL SYSTEM WILL MOVE OVER THE WATERS ON TUESDAY AND
WINDS WILL SHIFT MORE ONSHORE. IN ADDITION, THIS WILL CAUSE
INCREASED NORTHWESTERLIES ACROSS THE COASTAL WATERS. LATEST GUIDANCE
SUGGESTS THAT WINDS MAY MEET SMALL CRAFT THRESHOLDS. CHANCES OF
SUSTAINED WINDS AND GUSTS EXCEEDING 21 KT ARE 40-60% AND 50-80%,
RESPECTIVELY. HIGHEST PROBABILITIES ARE FOR THE OUTER COASTAL
WATERS. IN ADDITION SEAS WILL ALSO BUILD ON TUESDAY TO 8-11 FT.
ADDITIONAL WEAK SYSTEMS MAY MOVE ACROSS THE AREA WATERS LATER IN THE
WEEK.
29
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
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