textproduct: Seattle/Tacoma

SYNOPSIS

A cold front continues to move east of the Cascades this afternoon, resulting in a post-frontal onshore flow. Generally drier weather through Monday, with the exception being Sunday with a weak system moving by to the north. Another system brings lowland rain, increasing winds, and upper elevation mountain snowfall midweek.

SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/

A post-frontal airmass exists across Western Washington this afternoon. A convergence zone is located across portions of Snohomish and Skagit Counties with increasing west winds through the Strait of Juan de Fuca. The CZ will be rather shorter duration, and move into the Cascades into tonight, with only light, additional QPF amounts. Otherwise, some rivers continue to rise or crest (into Minor, Moderate, and Major flood stages) through Saturday with the rainfall through the week, refer to the .HYDROLOGY section for additional information.

Drier conditions are expected on Saturday, with a decent amount of sunshine as well. Clouds will most likely linger over central Puget Sound through the afternoon. Otherwise, a weak system will pass by to the north early Sunday, resulting in light precipitation across northern Western Washington, mainly along the Olympic Peninsula and north of Snohomish County. Temperatures will be cooler on Saturday, with highs in the upper 40s to low 50s, with temperatures a few degrees warmer Sunday.

LONG TERM /MONDAY THROUGH FRIDAY/

Drier conditions on Monday with some ridging influence, although clouds will continue ahead of the next frontal system. The next low pressure system will track into northern British Columbia on Tuesday, with a resulting front moving across Western Washington. Lowland rain, higher elevation mountain snowfall, and breezy winds are forecast for Tuesday. Unsettled conditions will continue Wednesday and Thursday with troughing over British Columbia, along with cooler conditions and snow levels closer to Pass level. Uncertainty exists in the pattern by Friday, but there are indications of generally drier conditions, and slowly warming temperatures. JD

AVIATION

Moist west to southwest flow aloft continues across western Washington as a front traverses the region. A weak Puget Sound Convergence Zone may linger into this evening as well. VFR has rebounded across the area aside from the coast. This trend will attempt to linger tonight into Saturday but a few pockets of MVFR may persist in and around convergence zone activity this evening.

KSEA...VFR currently as cigs have scattered this afternoon. Surface winds southerly 10 to 14 knots with gusts to 20-25 knots before diminishing towards 00-02z this evening. A transition to N/NE surface winds of 8 knots or less is presently expected to reach the terminal in the 01Z-03Z window. Low-end VFR to high-end MVFR tonight with high confidence VFR developing into Saturday.

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MARINE

A front has traversed across area waters this afternoon with breezy winds. Gale force gusts are possible through the Strait of Juan de Fuca tonight with the threat ending early Saturday morning. SCAs remain for the coast and portions of the inland waters but the threat should subside into Saturday morning as well. A surface ridge will slide eastward across the waters over the weekend. A strong frontal system will reach the waters Monday night into Tuesday with the potential for additional widespread wind/wave related headlines.

Coastal seas are expected to remain generally under 10 feet into Monday before a sub-990 millibar low passing over the offshore waters generates another round of double digit seas.

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HYDROLOGY

An active hydrologic situation continues to unfold across western Washington this afternoon. The front is progressing into the Cascades with lingering showers behind it. Given the rain tapering off, area rivers will continue to run elevated as local tributaries and other sources continue to feed the main stem rivers. In general, crests are expected to occur late tonight into the weekend. Flood warnings will persist until Sunday and Monday for a number of the forecast points. Rivers in King and Snohomish counties in particular are running in the moderate to major categories. A number of additional rivers throughout the area are between minor and moderate.

Precipitation tapers over the weekend and temperatures cool off. The next weather system is forecast to bring additional rain to the region next Tuesday and Wednesday.

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SEW WATCHES/WARNINGS/ADVISORIES

WA...Flood Watch until 5 PM PDT this afternoon for Cascades of Snohomish and Northern King Counties-Cascades of Southern King County-Cascades of Whatcom and Skagit Counties-City of Seattle-Downtown Everett / Marysville Area-Eastside- Foothills and Valleys of Central King County-Foothills and Valleys of Pierce and Southern King Counties- Foothills and Valleys of Snohomish and Northern King Counties-Foothills and Valleys of the North Cascades- Foothills of the Western and Southern Olympic Peninsula- Lowlands of Pierce and Southern King Counties-Lowlands of Western Skagit and Northwestern Snohomish Counties- Lowlands of Western Whatcom County-Middle Chehalis River Valley-Olympia and Southern Puget Sound-Olympics- Shoreline / Lynnwood / South Everett Area-Southern Hood Canal-Willapa and Black Hills.

PZ...Small Craft Advisory until 11 AM PDT Saturday for West Entrance U.S. Waters Strait Of Juan De Fuca.

Gale Warning until 3 AM PDT Saturday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory from 5 PM this afternoon to 11 AM PDT Saturday for Admiralty Inlet.

Small Craft Advisory until 5 PM PDT this afternoon for Puget Sound and Hood Canal.

Small Craft Advisory until 5 AM PDT Saturday 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.