438 FXUS66 KSEW 020957 AFDSEWArea Forecast Discussion National Weather Service Seattle WA 257 AM PDT Thu Oct 2 2025
.SYNOPSIS...An upper level low will sink southward today, wrapping moisture into western Washington as it does so. This will keep the chance for showers over the area. Dry conditions expected to emerge tonight. Although generally dry conditions are expected for the remainder of the forecast due to high pressure aloft, some weak disturbances may allow for a chance for showers this weekend.
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.SHORT TERM /TODAY THROUGH SATURDAY/...The upper level low continues to churn out over the Pacific, bringing in another wave of showers to the area as per current radar. Most activity is focused on the Olympic Peninsula and moving north-northeastward, so difficult to say how much of an impact this might have on locations east of the Sound, including the Seattle metro area. Ever since the sun went down last night, no lightning has been detected with this precip and as such will likely rely on daytime heating to introduce the energy necessary for convection. That said, models do show some instability, but it is primarily focused on the coastal waters and the immediate coastal area. Given the strongest activity seemed to be focused there yesterday, seems like a good fit for isolated thunderstorms to be a prospect there this afternoon and early evening.
The upper low wastes no time plunging to the south by this evening, taking the majority of its associated moisture with it. This should result in dry conditions over W WA as early as this evening, although most likely overnight tonight. Models remain on track for a strong upper level ridge to build over the Pacific, becoming the main influence to W WA weather for the remainder of the short term. As the ridge strengthens, temperatures will remain mild and seasonable...however there is some consistency in advertising a couple of weak disturbances on the leading edge of this ridge. This could result in slight chance to chance PoPs over the area at times Friday evening into Saturday, but probabilities remain low enough to add some confidence to a generally dry close to the short term.
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.LONG TERM /SUNDAY THROUGH WEDNESDAY/...The upper level ridge remains the main weather feature for the long term portion of the forecast as its axis gradually shifts eastward throughout the period. This looks to ensure dry conditions for the first half of next week. This feature will initiate a warming trend, bringing a return to daytime highs in the lower 70s in the interior lowlands Monday and Tuesday. Some ensemble members hinting at an upper level trough sinking down toward the area late Tuesday into Wednesday, pushing the ridge axis back westward and out to sea. While this could reintroduce rain to the forecast, given how far out this would occur along with this being a relatively new-ish solution, not much confidence at this time. As such, the low PoPs provided by the NBM is in line with current thinking until this solution becomes either more consistent, includes more members or both.
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.AVIATION...Southwest flow aloft continues over western Washington as an upper level low starts to move onshore. VFR conditions for all area terminals early this morning will continue throughout the remainder of the day. Areas along the coast may drop down to MVFR early this morning, but will rebound to VFR by the afternoon. Southerly winds will continue to be breezy this morning with gusts up to 20 to 25 kts, tapering off by the afternoon with a more southwesterly direction.
KSEA...VFR conditions this morning with lingering rain showers will dissipate by early afternoon. VFR conditions will continue throughout the day. Southerly winds this morning 5 to 10 knots returning more southwesterly later this afternoon, maintaining the same speed.
Mazurkiewicz
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.MARINE...Gale force southerly winds will start to decrease in strength later this morning as a weather system starts to weaken offshore. Winds will lower to small craft strength, therefore have continued the Small Craft Advisories for the Coastal Waters, Eastern Entrance of the Strait, and the Northern Interior Waters until this afternoon. Winds will continue to become light heading into Friday, along with winds taking a more northerly direction into the weekend.
There remains a 15-20% chance of thunderstorms over the Coastal Waters this afternoon. Convective showers or thunderstorms may be accompanied by brief erratic winds and small hail. The thunderstorm threat over the Coastal Waters will diminish by the evening hours.
Combined seas this morning of 15 to 18 feet. Seas will subside later this morning 13 to 15 feet, and further lowering below 10 feet by this evening. Seas will lower to 4 to 6 feet by Friday morning and maintain that height over the weekend.
Mazurkiewicz
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.SEW WATCHES/WARNINGS/ADVISORIES... WA...High Surf Advisory until 5 AM PDT early this morning for Grays Harbor County Coast-Northern Washington Coast.
Wind Advisory until 5 AM PDT early this morning for Island County.
PZ...Small Craft Advisory until 5 PM PDT this afternoon for Grays Harbor Bar.
Small Craft Advisory until 5 AM PDT early this morning for Admiralty Inlet-Central U.S. Waters Strait Of Juan De Fuca- Puget Sound and Hood Canal-West Entrance U.S. Waters Strait Of Juan De Fuca.
Gale Warning until 5 AM PDT early this morning for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm- Coastal Waters From Cape Flattery To James Island Out 10 Nm- Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm-East Entrance U.S. Waters Strait Of Juan De Fuca-Northern Inland Waters Including The San Juan Islands.
Small Craft Advisory until 2 PM PDT this afternoon for East Entrance U.S. Waters Strait Of Juan De Fuca-Northern Inland Waters Including The San Juan Islands.
Small Craft Advisory until 5 PM PDT this afternoon for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm- Coastal Waters From Cape Flattery To James Island Out 10 Nm- Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm.
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NWS SEW Office Area Forecast Discussion