990
FXUS66 KSEW 112205
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
305 PM PDT THU SEP 11 2025
SYNOPSIS
THE UPPER TROUGH OVER THE REGION WILL CONTINUE
SLIDING EASTWARD TONIGHT WITH ANOTHER ROUND OF WIDESPREAD CLOUDS
AND AREAS OF FOG DEVELOPING EARLY FRIDAY. WEAK HIGH PRESSURE
BUILDS OVER THE INTERIOR WITH DRY CONDITIONS THROUGH EARLY
SATURDAY. A COLD FRONT LIKELY MOVES THROUGH THE REGION LATE
SATURDAY THROUGH SUNDAY, WITH WIDESPREAD RAIN. WARMER AND DRIER
CONDITIONS DEVELOP EARLY NEXT WEEK.
SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/
THE CLOUDS HAVE
BEEN THE BIG WEATHER STORY ACROSS WESTERN WASHINGTON TODAY WITH
MANY AREAS OF DENSE FOG EARLY THIS MORNING GIVING WAY TO
PERSISTENT LOW STRATUS THIS AFTERNOON. THE STRATUS CONTINUES TO
SCATTER, WITH SOME BREAKS OF SUN, ESPECIALLY ACROSS THE NORTHERN
PORTIONS OF THE AREA. THE UPPER LOW CONTINUES TO SHIFT EASTWARD
INTO FRIDAY, WITH ONSHORE FLOW LIKELY LEADING TO ANOTHER CLOUDY
START WITH POCKETS OF LOCALLY DENSE FOG. TRANSIENT HIGH
PRESSURE ALOFT ON FRIDAY WILL MAINTAIN DRY CONDITIONS ACROSS THE
REGION. THE NEXT FRONTAL SYSTEM THEN APPROACHES DURING THE DAY
SATURDAY, LIKELY PUSHING ONSHORE LATE SATURDAY EVENING.
LONG TERM /SUNDAY THROUGH WEDNESDAY/
EXPECT INCREASING RAIN
AREA-WIDE BY EARLY SUNDAY, WITH A STRONGER COLD FRONT SWEEPING
ACROSS THE REGION. FAIRLY STRONG AGREEMENT IN THE ENSEMBLE
GUIDANCE FOR THIS FRONTAL PASSAGE, WITH THE MAJORITY OF THE RAIN
FALLING VERY LATE SATURDAY THROUGH EARLY SUNDAY, WITH LINGERING
SHOWERS DURING THE DAY SUNDAY. AN EARLY LOOK AT MOST LIKELY
RAINFALL AMOUNTS WOULD BRING AROUND ONE HALF INCH OF RAIN TO THE
INTERIOR LOWLANDS AND CLOSER TO AN INCH OR MORE TO THE MOUNTAIN
AND COASTLINE, THOUGH THERE IS STILL A DECENT AMOUNT OF SPREAD
WITH RESPECT TO POTENTIAL RAINFALL AMOUNTS. THE CHANCE OF
WETTING RAIN OF 55% OR BETTER IN THE MOUNTAINS SATURDAY NIGHT
INTO SUNDAY, WITH AROUND A 35% CHANCE THROUGH THE LOWLANDS ARE
CONSISTENT WITH THESE MOST LIKELY AMOUNTS. RAIN TAPERS LATER
SUNDAY INTO MONDAY WITH SOME DIFFERENCES IN THE GUIDANCE
BEGINNING TO EMERGE. A DRYING TREND THEN DEVELOPS INTO TUESDAY
WITH A RIDGE OF HIGH PRESSURE BUILDING OVER THE WESTERN U.S.
IT'S WORTH NOTING THAT THOUGH SEEMINGLY BRIEF, THERE IS SOME
POTENTIALLY FOR OFFSHORE FLOW TO DEVELOP OVER PORTIONS OF THE
AREA. WHILE INITIAL INDICATIONS ARE THAT IT'LL BE SHORT DURATION
AND NOT PARTICULARLY STRONG, IT COULD BRING ABOUT ANOTHER BUMP
IN POTENTIAL FIRE WEATHER CONCERNS DESPITE THE WETTER PATTERN
BETWEEN NOW AND THEN. CULLEN
AVIATION
UPPER LEVEL LOW CENTERED OVER NORTHERN CALIFORNIA WILL
GRADUALLY MOVE EAST TONIGHT INTO FRIDAY. NORTH-NORTHEASTERLY FLOW
WILL GRADUALLY TURN WESTERLY DURING THIS TIME AS A TRANSIENT RIDGE
SHIFTS OVERHEAD. ONSHORE FLOW EXISTS IN THE LOWER LEVELS. HIGH-END
IFR TO MVFR CEILINGS ARE LINGERING ACROSS PUGET SOUND, THE COAST,
AND SOUTHWEST INTERIOR. IMPROVEMENT TO VFR SHOULD BE MET AROUND 22-
00Z BUT AN ADDITIONAL ROUND OF LOW STRATUS (LIFR/IFR) AND FOG IS
EXPECTED TO REDEVELOP OVERNIGHT INTO FRIDAY MORNING. BUT AGAIN,
CLEARING TO VFR IS EXPECTED INTO FRIDAY AFTERNOON.
KSEA...900 FT CEILINGS AT THE TERMINAL AT THIS HOUR. HOWEVER,
STRATUS IS SCATTERING ALLOWING VFR CIGS TO RETURN BY 23Z. LOW
STRATUS AND FOG LOOKS TO REDEVELOP AROUND 10-12Z FRIDAY AND PERSIST
THROUGH THE MORNING BEFORE SCATTERING AGAIN IN THE AFTERNOON. SW
WINDS 3-6 KT THROUGHOUT THE PERIOD.
MCMILLIAN
MARINE
WEAK HIGH PRESSURE OVER THE WATERS WILL KEEP ONSHORE FLOW
PATTERN GOING THROUGH FRIDAY NIGHT. FRONT MOVING INTO THE COASTAL
WATERS SATURDAY AND INLAND SUNDAY. HIGH PRESSURE REDEVELOPS AGAIN
FOR THE FIRST PART OF NEXT WEEK. SMALL CRAFT ADVISORY WESTERLY WINDS
IN THE CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA TONIGHT AND AGAIN
SUNDAY NIGHT. SMALL CRAFT ADVISORY WINDS POSSIBLE OVER THE COASTAL
WATERS SUNDAY. OFFSHORE FLOW IS FAVORED TO REDEVELOP ON TUESDAY.
SEAS GENERALLY IN THE 5 TO 7 FOOT RANGE WITH SLIGHTLY HIGHER SEAS
POSSIBLE SUNDAY INTO SUNDAY NIGHT. SEAS THEN BELOW 5 FT EARLY NEXT
WEEK.
MCMILLIAN
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 2 AM PDT FRIDAY
FOR CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-EAST
ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
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