textproduct: Seattle/Tacoma

SYNOPSIS

Showers are diminishing across the area this morning, with a ridge expected to build through the end of the week. The pattern shifts to unsettled over the weekend with cooler temperatures and another chance for rain through early next week.

SHORT TERM /TODAY THROUGH FRIDAY/

Shower activity has largely moved out of the CWA this morning, with cloudy skies expected to linger until early afternoon. Clearing skies are expected this afternoon. No major updates have been made to the forecast. See below for an updated aviation discussion.

High pressure and offshore flow will lead to drier and warmer weather Thursday and Friday. Expect highs on Thursday in the lower 70s with 60s near the water. Offshore flow will strengthen Thursday night with gusty east Cascade gap winds of 20-30 MPH. Friday will be slightly warmer in the interior with highs in the mid 70s. 33

LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/

Friday night and Saturday will be cooler and wetter as a cold front and trailing trough push into western WA. Showers with a convergence zone are likely Saturday afternoon/evening near the King/Snohomish line. High will be cooler and in the 50s and 60s Saturday afternoon. Expect cooler lows Sunday morning with 30s around the south sound. The system slated for Sunday and Monday is now shifting south over the offshore waters, missing WA, with lower probabilities of seeing gusty winds. The air mass will still be cool and showery with a trough overhead, though. Expect a chance of showers moving into Tuesday before the trough exits. 33

AVIATION

A weak frontal system crossing the area will continue to bring light rain showers to portions of western Washington through late this morning. Ceilings are a bit of a mixed bag this morning, ranging mostly from IFR to MVFR. Ceilings will slowly lift and scatter by late morning/early afternoon (between 18-21Z) across the interior, and may not fully scatter along the coast until after 00-03Z this evening. Light winds and clearing skies tonight will allow for low stratus/fog development going into early Thursday morning.

Winds remain southwesterly 4-8 kt and will become light/variable before switching to northerly, 5 kt or less, by around 00Z.

KSEA...MVFR ceilings this morning. Ceilings look to lift to VFR after around 18Z and will slowly scatter through the afternoon. Clearing skies and light winds will allow for fog/low stratus to develop overnight into Thursday morning, with probabilistic guidance indicating a 25-35% chance of LIFR conditions developing around 12Z Thur. SW winds 4-8 kt will become light before switching to N/NE around 00Z Thur.

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MARINE

A weak front will continue to traverse the area waters this morning. High pressure will quickly build in across the offshore waters tonight, with thermal troughing developing along the coast. This will allow for winds to turn offshore tonight into Thursday. While winds are favored to remain below any thresholds for headlines, there will be some enhancement to the winds through the gaps, with a 20-40% chance for gusts to exceed 20 kt near the west entrance to the Strait of Juan de Fuca and around Grays Harbor. Winds will ease on Friday as the thermal trough gets pushed inland by an incoming frontal system. Onshore flow will start to increase as a frontal system traverses the area Friday night into Saturday. Another low may follow suit Sunday into Monday but there are significant differences in the exact low track.

Seas remain around 4 to 7 ft through Friday, increasing through the weekend. The most likely forecast is around 8 to 10 ft, though seas could reach as high as 13-16 ft Sunday into Monday, depending on the track of the low pressure systems as they move across the northeast Pacific. GEFS is showing 40-50% chances of seeing greater than 12 ft during that time frame.

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SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...None.