Marine Weather and Tide Forecast for Seattle, WA

SHORT TERM /TODAY THROUGH THURSDAY/
A low pressure system stalled over British Columbia will continue to send a series of waves across western Washington through Wednesday, maintaining cooler temperatures with continued shower activity and a chance for isolated afternoon thunderstorms. Temperatures will peak in the mid to upper 50s along the coast and in the low 60s further inland under cloudy skies. Onshore flow will also promote the potential for areas of fog and low stratus each morning, especially across the lowlands near the Puget Sound. Convergence zone showers are expected to linger Wednesday morning along the King/Snohomish County line before tapering off late Wednesday morning as the upper low dissipates.

A trough axis will shift inland throughout the day Wednesday, with the bulk of the moisture associated with this system moving to our south. Shower activity will mostly be confined to the south of the Puget Sound through the afternoon and evening Wednesday, with a slight chance of additional showers over the mountains.

Weak ridging is favored to pass over the region on Thursday, allowing conditions to warm up and dry out. High temperatures will return to near normal for mid May with plenty of sun breaks.

LONG TERM /FRIDAY THROUGH MONDAY/
Forecast confidence decreases heading into the weekend, with some uncertainty over precipitation on Friday. The placement of an approaching cutoff low will determine whether western Washington stays dry or sees some showers, but ensembles continue to favor a drier and warmer solution. An upper level ridge will amplify over the western US by Saturday, with southwest flow bringing some warming to western Washington. By Sunday, most of the interior lowlands will likely see high temperatures well into the 70s with mostly clear skies.

Deterministic forecast models hint at a front crossing western Washington on Monday, bringing in cooler conditions. However, models remain fairly consistent over splitting the front as it moves inland, keeping western Washington on the drier side. Any incoming showers that materialize would be light in nature, only dropping a few hundredths of an inch. Both operational and ensemble forecasts also suggest that ridging could dominate the forecast into early next week, but models continue to show a wide spread in solutions.

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AVIATION
Upper level troughing to the north will continue to promote zonal flow aloft through the TAF period. Scattered shower activity continues for areas along the Olympic Peninsula and for areas generally north of KPAE early this morning, with many of the central Sound terminals currently remaining rain shadowed.

Conditions have been a mixed bag of VFR to MVFR at the terminals overnight. Expect cigs to gradually lower area-wide later this morning, with most sites expected to drop between MVFR to low-end VFR. Gradual improvement towards VFR is expected again by the afternoon, however shower activity will continue throughout the day and could bring localized pockets of reduced cigs and vis at times. Isolated thunderstorms will also be possible across the region today, but confidence remains too low to include in any single TAF issuance at this time. Increasing onshore flow tonight will likely aid in the development of a convergence zone over Snohomish/King counties between 03-06Z. Southerly surface winds will generally persist for interior terminals between 7-12 kt today and could become breezy this afternoon with gusts to 18-20 kt possible. Westerly surface winds expected for coastal terminals between 10-15 kt.

KSEA.. MVFR cigs this morning, though expect gradual improvement to VFR again by this afternoon. Scattered shower activity through the day could briefly bring a reduction to cigs and vis to the terminal at times. Convergence zone development looks to remain north of the terminal tonight. S/SW winds at 7-12 kt, with gusts to 20 kt possible this afternoon.

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MARINE
Onshore flow will continue across the region, with a weak westerly push expected through the Strait of Juan de Fuca tonight. While sustained winds look to generally remain between 15-20 kt, probabilistic guidance highlights a 60-80 percent chance of wind gusts reaching small craft criteria across portions of the central and eastern Strait for a brief period tonight. Thus, have gone ahead and issued a small craft advisory for these areas.
Small craft advisories also remain in effect for the coastal waters and the Western Strait for seas between 10-13 ft today.
Seas are expected to gradually subside towards 8-10 ft again tonight into Wednesday.

Weak high pressure will build back into the area waters Wednesday and Thursday, bringing northwesterly winds to the coastal waters.
Seas will continue to subside towards 4-6 ft into Thursday. A weakening system may approach the waters on Friday, before high pressure builds into the coastal waters again over the weekend.
Another system may approach the area waters again late in the weekend into early next week.

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SEW WATCHES/WARNINGS/ADVISORIES
WA...None.
PZ...Small Craft Advisory until 6 PM PDT this evening for Grays Harbor Bar.

Small Craft Advisory from 8 PM this evening to 2 AM PDT Wednesday for Central U.S. Waters Strait Of Juan De Fuca- East Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory until 6 PM PDT this evening 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.