216
FXUS66 KSEW 051535
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
835 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
AN UPPER LEVEL HIGH BUILDING OVER THE AREA FROM THE
NORTHEASTERN PACIFIC WILL KEEP WINDS ALOFT FROM THE N/NE THROUGH
THE TAF PERIOD. SATELLITE IMAGERY THIS MORNING SHOWS AREAS OF FOG
AND LOW CLOUDS ACROSS PORTIONS OF THE CENTRAL AND SOUTH SOUND
THIS MORNING, AS WELL AS ALONG THE SOUTHWEST INTERIOR. THIS HAS
RESULTED IN A MIX OF CEILINGS ACROSS THE AREA TERMINALS, WITH
CEILINGS GENERALLY RANGING FROM VFR FOR TERMINALS WITH CLEAR
SKIES TO MVFR/IFR FOR TERMINALS IN STRATUS/FOG. SATELLITE TRENDS
THIS MORNING ALREADY SHOW CLOUDS AND FOG STARTING TO SCATTER, SO
EXPECT OVERALL AREA-WIDE IMPROVEMENT FOR LOWER CIG TERMINALS TO
VFR BY 18-19Z. VFR CONDITIONS WILL THEN PERSIST THROUGH THE REMAINDER
OF THE DAY. WINDS HAVE ALREADY STARTED TO INCREASE THIS MORNING
FOR SOME CENTRAL PUGET SOUND TERMINALS AND WILL GENERALLY PERSIST
OUT OF THE NORTH BETWEEN 7-12 KT BEFORE EASING AGAIN TONIGHT.
WINDS FOR KCLM LOOK TO REMAIN LIGHT (BELOW 6 KT) AND SHIFT TO THE
EAST THIS MORNING.
KSEA...MVFR CEILINGS PERSIST THIS MORNING WITH STRATUS AT THE
TERMINAL. WINDS ARE PERSISTING OUT OF THE N/NE AT 8-12 KT, OVERLAPPING
WITH THE LOWER CIGS THIS MORNING. EXPECT OVERALL IMPROVEMENT BACK
TO VFR CONDITIONS BY 18Z. HOWEVER, SATELLITE IS ALREADY STARTING
TO SHOW SOME SCATTERING AROUND THE TERMINAL. SHOULD THIS CONTINUE,
IT COULD SPEED UP THE TIMING ON THE IMPROVEMENT BY AN HOUR OR TWO.
WINDS WILL EASE AGAIN TO 6-7 KT TONIGHT BY 06Z. GUIDANCE DOES
SUGGEST A RETURN OF MVFR CEILINGS ON MONDAY MORNING (A 25-35%
CHANCE).
14
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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