Seattle, WA 98144 Weather

Synopsis

Troughing will persist over the Pacific Northwest the remainder of today with unsettled conditions and periodic showers. A frontal system will arrive tonight into Wednesday for steadier rainfall and mountain snow. An upper low then lingers over Western Washington into late week for showers and cooler temperatures.

Short term

The current forecast remains on track with no planned updates tonight. 33

Previous discussion: Ongoing shower activity will continue throughout most of the area this afternoon and evening, ahead of an approaching frontal system. High temperatures this afternoon generally in the mid to upper 50s across the interior, with low 50s for areas along the water. Showers will turn into more steadier rainfall starting tonight and continuing into Wednesday morning. Southwest winds will also increase later this evening into Wednesday, peaking between 20 to 30 mph generally in the areas of the Southwest Interior through Shelton. As rainfall becomes steadier, we will also see the first widespread mountain snow event of the season unfold. A Winter Weather Advisory continues for all of the Cascade zones, with snow levels 4000 to 4500 feet dropping to 3000 to 3500 feet by Wednesday morning. Snowfall accumulations generally around 4 to 8 inches for Stevens Pass - with Snoqualmie pass seeing around 1 to 3 inches. Areas in the Southern Cascade Zone such as White Pass and Paradise will likely see higher amounts, around 6 to 12 inches of snow. Those traveling will want to be aware of the conditions and weather by checking with WSDOT for updates.

Upper level troughing will continue Wednesday into Thursday for spotty showers and cooler temperatures, with high temps ranging in the low to mid 50s for most areas.

Long term

Ensemble guidance continues to show troughing across the Pacific Northwest through Friday, which keeps scattered showers in the forecast. Snow levels hover around 2500 to 4000 feet on Friday, so could continue to see light snow accumulations in the Cascades. The upper level trough looks to slowly move out of the area over the weekend, with a drying trend over the weekend into early next week. High temperatures look to remain in the mid 50s over the weekend. with overnight lows approaching low to mid 30s. Will continue to monitor the threat of frost or freeze conditions.

Mazurkiewicz

Aviation

Convergent bands of rain continue to move east into the Cascades this evening in Snohomish County. Pockets of IFR ceilings linger in wake of the convergence zone between Everett and Mt. Vernon. Additional showers are working their way inland from the coast and will impact some of the Puget Sound terminals over the next several hours. Gusty winds continue out of the southwest at 25 kt, and will linger through late tonight. Light RA will return to inland terminals after 05Z with another round of lower cigs expected tomorrow morning. Probabilities of cigs less than 3000 ft are around 60-80% tonight after 06Z and 45-55% tomorrow morning between 15Z- 18Z.

KSEA: Gusty southwest winds will continue through roughly 05Z, with gusts to 20 to 25 kt. Mix of VFR and MVFR ceilings this evening. Rain will return late tonight and become more scattered after 09Z. Vicinity showers will persist through the end of the TAF period with MVFR cigs expected until tomorrow afternoon.

21/HPR

Marine

Northwesterly winds along the outer coastal waters will linger into Wednesday, with wind gusts approaching 25 kt at times and a SCA still in effect until late tonight. Seas will be between 8-9 feet overnight. Another frontal system will move into the waters tonight into Wednesday, increasing winds and seas across the area. Increasing onshore flow will bring a brief push of small craft westerly winds to the central and eastern Strait late this afternoon into this evening. Southerly winds are picking up along the Puget Sound waters this afternoon, with latest guidance highlighting a 60- 80% chance of gusts exceeding small craft criteria particularly in the waters from Seattle south.

Winds will ease again across the area waters on Wednesday as the accompanying surface low drops into the area and tracks southward along the coastal waters. This low will allow for flow to turn back offshore, with offshore flow persisting the second part of the week.

Sea conditions slowly subsiding back to 4-6 ft on Thursday and remain that way into the weekend.

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Watches, warnings and advisories

WA: Winter Weather Advisory until 5 PM PDT Wednesday for Cascades of Pierce and Lewis Counties-Cascades of Snohomish and Northern King Counties-Cascades of Southern King County- Cascades of Whatcom and Skagit Counties.

PZ: Small Craft Advisory until 11 PM PDT this evening for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca-Puget Sound and Hood Canal.

Small Craft Advisory until 5 AM PDT Wednesday 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.