textproduct: Seattle/Tacoma

SYNOPSIS

A post frontal convergence zone continues this morning, dissipating in the afternoon. Upper level trough offshore digging south Sunday and Monday with the next system moving by to the west. Temporary upper level ridge Tuesday moving east Wednesday. Another splitting system arriving Thursday. Cool upper level trough over Western Washington Friday.

SHORT TERM /TODAY THROUGH MONDAY/

A convergence zone continues this morning across King County into the central Cascades. Precipitation will slowly dissipate in this area into the early afternoon. Outside of the convergence zone not much in the way of cool air behind the front leading to minimal post frontal shower activity. Skies clearing this afternoon with partly to mostly sunny skies across the area. With the sunshine highs near or slightly above normal, in the upper 50s to mid 60s.

Not much going on tonight. Zonal flow aloft with surface high pressure building into the area. Light gradients overnight brings up the potential for some fog formation early Sunday morning especially in the fog prone locations like the Southwest Interior. Lows in the mid 30s to mid 40s.

Surface high pressure remaining over Western Washington Sunday. Flow aloft becoming southwesterly with an upper level trough kicking out of the Gulf of Alaska digging south well offshore. This will spread some high clouds over the area during the day. Highs a little cooler with the cool morning to start things off, in the mid 50s to lower 60s.

Upper level trough continuing to dig south Sunday night into Monday with the associated frontal system moving by to the west Monday. Rain chances confined to the coastal waters but with the system in the vicinity plenty of middle and high level cloud cover by Monday. Lows in the mid 30s to mid 40s. Highs Monday again in the mid 50s to lower 60s. Felton

LONG TERM /MONDAY NIGHT THROUGH FRIDAY/

Models in good agreement with the upper level trough dropping down the California coast through Tuesday leaving Western Washington in a lull. Surface gradients going northerly for another dry day Tuesday with highs near normal, mid 50s to lower 60s. Cool mornings both Tuesday and Wednesday with the coldest locations near freezing. Another round of frost advisories may be needed.

Upper level trough approaching the coast Wednesday. Frontal system associated with the trough still well offshore Wednesday afternoon. Mostly sunny skies with highs a touch warmer, upper 50s to mid 60s.

Front slowing down and splitting Wednesday night with what is left of the system moving inland Thursday for a chance of showers. Lows in the mid 30s to mid 40s. Highs in the mid to upper 50s.

Possible post frontal convergence zone Thursday night. Weak upper level trough moving over the area hanging around through Friday. Chance of showers Thursday night becoming confined to the Cascades Friday. Little change in temperatures from Thursday's highs and lows.

Quick note on the 77 degree day in Seattle Friday. This was the second warmest day on record for this late in the year. The only day warmer was the record setting 88 degree day back in 2022. The warmest days on record from here until March are 74 degree days on October 17, 1989, November 3 2010 and November 4, 1949. 77 degrees is the normal high in Seattle from August 19 through 25. The normal high for Seattle yesterday is 60 degrees. Felton

AVIATION

Westerly flow aloft will continue into tonight as a frontal system shifts east of the area. The low level flow is onshore and will gradually weaken this afternoon into tonight. MVFR ceilings and a few pockets of IFR in rain remain around central Puget Sound this morning as a convergence zone gradually shifts southward into King County. Ceilings will improve around Puget Sound toward mid- afternoon as the convergence zone dissipates with VFR expected for the remainder of the area this afternoon. Light surface winds and low level moisture will lead to the formation of IFR/LIFR fog and low clouds on Sunday morning...especially across the Southwest Interior and south portions of Puget Sound.

KSEA...The convergence zone is shifting southward into northern portions of King County as of 16Z with a N/NE wind shift on track to reach the terminal around 18Z-19Z. Ceilings are expected to lift to VFR toward 20Z or so as the convergence zone begins to dissipate. Confidence is fairly high that some LIFR fog and low clouds will be around the terminal on Sunday morning and will include that in upcoming TAF. Surface winds shifting to E/NE around 18Z then becoming N/NE 5 to 8 knots this afternoon into tonight.

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MARINE

A frontal system is moving through the area this morning. Seas will be between 8-10 feet with the highest waves over the offshore waters. As a result, SCAs remain over the outer coastal waters (for seas) and central/eastern strait (for winds) until tonight. High pressure building over the waters Saturday afternoon will remain through Sunday. Another system will move by west of the coastal waters Monday. High pressure will rebuild over the area Tuesday with seas subsiding back down to 4 to 6 feet around this time.

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SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory until 6 PM PDT this evening for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory until 8 PM PDT this evening for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm- Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm.