314
FXUS66 KSEW 130407
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
907 PM PDT FRI SEP 12 2025
SYNOPSIS
WEAK HIGH PRESSURE OVER THE REGION THROUGH
SATURDAY. A COLD FRONT WILL THEN MOVE THROUGH SATURDAY NIGHT
INTO SUNDAY, WITH RAIN AND SHOWERS. WARMER AND DRIER CONDITIONS
DEVELOP EARLY NEXT WEEK. A BROAD UPPER TROUGH IS THEN LIKELY TO
MOVE OVER THE REGION DURING THE SECOND HALF OF NEXT WEEK.
SHORT TERM /TONIGHT THROUGH MONDAY/
TRANSIENT HIGH PRESSURE
ALOFT AS THE NEXT INCOMING DISTURBANCE SITS WELL OFFSHORE.
MARINE STRATUS IS GRADUALLY SCATTERING THIS AFTERNOON BUT
WIDESPREAD COVERAGE STILL REMAINS WITH MOSTLY CLOUDY SKIES
PREVALENT FOR PUGET SOUND, SOUTHWEST INTERIOR AND THE COAST. FOR
TONIGHT, THE AFOREMENTIONED RIDGE AXIS WILL TRACK DIRECTLY
OVERHEAD WITH MOSTLY DRY CONDITIONS. CAN'T RULE OUT AREAS OF
DRIZZLE SQUEEZING OUT OF DEVELOPING MARINE STRATUS AND PATCHY
FOG. OVERNIGHT LOWS ARE TO BOTTOM INTO THE LOWER TO MID 50S.
UPPER-LEVEL PROGRESSION WILL LEAD INTO SATURDAY AS THE RIDGE
CROSS EAST OF THE CASCADES. MORNING CLOUDS WILL START THE DAY YET
AGAIN BUT SHOULD GIVE WAY TO AFTERNOON SUNSHINE. HOWEVER, HIGH
CLOUDS ARE SLATED TO BUILD OVERHEAD SATURDAY NIGHT AS A PRECURSOR
OF THE NEXT RAIN MAKER. A COLD FRONT WILL ARRIVE AT THE COAST BY
EARLY SUNDAY MORNING, SPREADING PRECIPITATION AS THE DAY PROGRESS.
TOTAL RAINFALL AMOUNTS RANGE FROM 0.25-0.50" ALONG THE MOUNTAINS
TO AROUND 0.10-0.25" FOR THE LOWLANDS. THE AIR MASS WILL BE
SLIGHTLY UNSTABLE WITH A CHANCE OF THUNDERSTORMS TOO.
A FEW SHOWERS POSSIBLE INTO MONDAY MORNING AS A LINGERING
CONVERGENCE ZONE FIZZLES OUT. DRIER WEATHER REBOUNDS ACROSS THE
REGION AS RIDGING RETURNS. SEASONAL TEMPERATURES WILL COOL DOWN
SUNDAY INTO MONDAY AND TREND SLIGHTLY BELOW AVERAGE FOR MID-
SEPTEMBER.
LONG TERM /TUESDAY THROUGH FRIDAY/
DRIER WEATHER IS FAVORED
TO PERSIST INTO TUESDAY. HIGHS TUESDAY AND WEDNESDAY WILL REACH
THE MID TO UPPER 70S WITH A FEW LOW 80S POSSIBLE. CRITICAL FIRE
WEATHER CONDITIONS REMAIN LOW WITH HIGHER HUMIDITIES, PARTICULARLY
INTO TUESDAY AS OFFSHORE LOOKS TO RETURN BRIEFLY. A TROUGH MAY
BRING COOLER AND WETTER CONDITIONS MOVING TOWARD THE END OF THE
WEEK.
MCMILLIAN
AVIATION
AN UPPER LEVEL RIDGE BUILDS OVER THE REGION WITH
GENERALLY LIGHT LOW LEVEL FLOW. THIS WILL BRING A RETURN OF LOW
STRATUS WITH IFR CEILINGS AND FOG ACROSS MUCH OF THE INTERIOR
LATE TONIGHT THROUGH SATURDAY MORNING. CONFIDENCE IS ONLY
MODERATE FOR THE PUGET SOUND TERMINALS, BUT HIGHER ELSEWHERE.
EXPECT INCREASINGLY SOUTHERLY FLOW SATURDAY AS A COLD FRONT
APPROACHES. SURFACE WINDS BECOMING PREDOMINANTLY SOUTHERLY AND
INCREASING TO 5-7 KT WITH SCATTERING OF LOW CLOUDS 17-20Z,
FOLLOWED BY ADDITIONAL MID LEVEL CLOUDS INCREASING HEAD OF THE
FRONT.
KSEA...LIGHT AND VARIABLE WINDS AT THE TERMINAL OVERNIGHT WITH A
LIKELY RETURN OF STRATUS AROUND 12Z WITH WEAK HIGH PRESSURE
ALOFT. EXPECT CEILINGS 500 FT OR LESS FOR A FEW HOURS, BEFORE
LIFTING AND SCATTERING OCCURS BY 18Z. PREDOMINANTLY SOUTHERLY
WINDS AROUND 6 KT THROUGH THE DAY, WITH INCREASING MID LEVEL
CLOUDS THROUGH THE DAY AHEAD OF THE APPROACHING FRONT. CULLEN
MARINE
ONSHORE FLOW WILL CONTINUE THROUGH FRIDAY NIGHT WITH
WEAK HIGH PRESSURE REMAINING OVER THE WATERS (AND LOWER PRESSURE
INLAND). A FEW AREAS MAY SEE FOG TONIGHT (ESPECIALLY IN THE
COASTAL WATERS AND THE STRAIT OF JUAN DE FUCA). A COLD FRONT
WILL APPROACH THE COASTAL WATERS SATURDAY, AND CROSS INLAND
SUNDAY. PROBABILITIES HAVE INCREASED FOR A PERIOD OF WIND GUSTS
EXCEEDING 20 KT IN THE COASTAL WATERS AND STRAIT OF JUAN DE FUCA
SUNDAY - WILL CONTINUE TO MONITOR FOR A POSSIBLE SMALL CRAFT
ADVISORY. ONCE THE FRONT PASSES, ONSHORE FLOW WILL RETURN
TUESDAY, WITH SOME MODELS INDICATING ANOTHER POSSIBLE SYSTEM
MIDWEEK.
SEAS WILL BUILD TO 6-8 FT THROUGH THE WEEKEND (WITH THE PERIOD
DROPPING TO 8-10 SECONDS ON SUNDAY), BUT WAVE HEIGHTS WILL DECREASE
DOWN TO 4-6 FT NEXT WEEK.
HPR
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
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