864
FXUS66 KSEW 082029
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
129 PM PDT TUE SEP 8 2026
SYNOPSIS
AN UPPER RIDGE OFFSHORE WILL BRING DRY, WARMER
CONDITIONS THROUGH WEDNESDAY. TROUGHING DEVELOPS OVER THE
PACIFIC NORTHWEST THURSDAY WITH AN UPPER LOW BRINGING COOLER
CONDITIONS AND PRECIPITATION POTENTIAL INTO THE WEEKEND.
SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/
MOSTLY SUNNY CONDITIONS TODAY WITH A FEW CLOUDS MAINLY OVER THE
HIGHER ELEVATIONS. AN UPPER RIDGE OFFSHORE BUILDS INTO WESTERN
WASHINGTON ON WEDNESDAY, RESULTING IN WARMER TEMPERATURES AND
CONTINUED DRY CONDITIONS. HIGHS ON WEDNESDAY ARE EXPECTED TO
RANGE IN THE 70S TO LOW 80S. THE RIDGE BEGINS TO FLATTEN
WEDNESDAY NIGHT AS TROUGHING DEVELOPS ON THURSDAY. WIDESPREAD
CLOUDS THURSDAY AM WILL RESULT IN COOLER CONDITIONS. INCREASING
ONSHORE FLOW MAY ALSO RESULT IN THE DEVELOPMENT OF WEAK
CONVERGENCE BY LATE THURSDAY OVER CENTRAL PUGET SOUND AND INTO
THE CASCADES.
LONG TERM /FRIDAY THROUGH TUESDAY/
TROUGHING FURTHER DEVELOPS OVER THE PACIFIC NORTHWEST ON FRIDAY
WITH A CONTINUED COOLING TREND LATE IN THE WEEK. ENSEMBLES ARE
IN GENERAL AGREEMENT THAT AN UPPER LOW MOVES SOUTHWARDS OFFSHORE
FRIDAY BEFORE MOVING INLAND OVER WA/OR DURING THE WEEKEND. RAIN
POTENTIAL INCREASES AS THE UPPER LOW MOVES INLAND, PARTICULARLY
SATURDAY INTO SATURDAY NIGHT. THERE IS ALSO A 10 TO 15 PERCENT
PROBABILITY FOR THUNDERSTORMS SATURDAY AFTERNOON. SOME
UNCERTAINTY IN THE ENSEMBLES AS TO HOW QUICKLY THE TROUGHING
MOVES EASTWARDS SUNDAY INTO MONDAY. HOWEVER, LINGERING
PRECIPITATION IS LIKELY AT LEAST OVER THE CASCADES ON SUNDAY
BEFORE A SLOW WARMING TREND BEGINS EARLY NEXT WEEK WITH RIDGING
OFFSHORE. JD
AVIATION
VFR CONDITIONS WILL CONTINUE TO PREVAIL ACROSS WESTERN
WASHINGTON THROUGH TONIGHT WITH MOSTLY CLEAR SKIES. MODELS ARE
HINTING AT SOME MARINE STRATUS DEVELOPMENT EARLY WEDNESDAY
MORNING, BUT THE MOST LIKELY AREA REMAIN THE COAST, WITH LESS
THAN A 20-25% CHANCE ELSEWHERE. SOME PATCHY VALLEY FOG MAY
DEVELOP FOR THE MORE SHELTERED TERMINALS AS WELL (OLM, PAE).
LOW CLOUDS AND FOG OUT QUICKLY AGAIN TOMORROW MORNING, THROUGH
HIGH CLOUDS WILL BEGIN TO BUILD IN FROM THE NORTH. WINDS REMAIN
NORTHERLY 10 KT OR LESS THROUGH THE PERIOD.
KSEA...VFR CONDITIONS PREVAIL THROUGH THE TAF PERIOD. NORTHERLY
WINDS PREVAIL AT AROUND 4 TO 8 KT.
62
MARINE
HIGH PRESSURE WILL CONTINUE TO BUILD OVER THE COASTAL WATERS
THROUGH EARLY THURSDAY. NORTHWESTERLY WINDS WILL PREVAIL OVER
THE COASTAL WATERS, BUT WILL INCREASE MORESO WEDNESDAY NIGHT AS
A WEAK FRONTAL SYSTEM FROM THE NORTH TIGHTENS THE PRESSURE
GRADIENTS. NORTHWEST WINDS OVER THE FAR OUTER COASTAL WATERS
COULD REACH UP TO AROUND 20 KT (30-50% CHC), WITH BETTER CHANCES
OF SEEING SMALL CRAFT ADVISORY WINDS BEING THROUGH PORTIONS OF
THE STRAIT OF JUAN DE FUCA (60-90% CHC). WINDS LOOK TO SLOWLY
EASE THURSDAY NIGHT. ANOTHER WEATHER SYSTEM MAY MOVE OVER THE
WATERS LATE FRIDAY INTO SATURDAY, BUT NO HEADLINE WINDS ARE
ANTICIPATED AT THIS TIME.
SEAS AROUND 3 TO 5 FEET WILL GRADUALLY BUILD THROUGH WEDNESDAY,
REACHING 7 TO 10 FEET BY THURSDAY AFTERNOON. THIS WILL ALSO
BRING STEEP SEAS AS SHORT PERIOD WAVES FROM THE STRONGER WINDS
OVER THE COASTAL WATERS BEGIN TO DOMINATE. SEAS WILL EASE TO
AROUND 5 TO 6 FEET BY FRIDAY, THEN FURTHER EASING INTO THE
WEEKEND.
62
FIRE WEATHER
DRY, WARM WEATHER CONTINUES THROUGH WEDNESDAY.
GIVEN THE RECENT COOL CONDITIONS, THIS WILL GENERALLY RETURN
FIRE WEATHER CONDITIONS BACK TO SEASONAL LEVELS OF CONCERN, WITH
LOCALIZED ELEVATED CONDITIONS WEDNESDAY. LIGHT OFFSHORE FLOW
TUESDAY NIGHT INTO WEDNESDAY WILL YIELD MODERATE RH RECOVERIES
ALONG THE RIDGES OF THE CASCADES AND OLYMPICS. DAYTIME RH VALUES
WILL APPROACH THE LOW TO MID 20 PERCENT RANGE WEDNESDAY OVER
THE CASCADES AND NEARBY VALLEYS. HOWEVER, THIS PERIOD OF
WARMER, DRY CONDITIONS WILL REMAIN SHORT-LIVED AS ONSHORE FLOW
RETURNS LATER THURSDAY FOR INCREASING RH VALUES. COOLER
CONDITIONS, ALONG WITH PRECIPITATION CHANCES, THEN CONTINUES
OVER THE WEEKEND. JD
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page