Marine Weather and Tide Forecast for Vashon, WA

SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/
Temperatures have cooled to the mid and upper 30s this evening with obs and cameras showing some slushy snow falling on surfaces in the Everett area. Precip rates in northern Snohomish County are likely pulling down some colder air and thus contributing to the frozen precip type. Elsewhere, it remains mainly rain across the lowlands.
Current thinking remains that accumulation at or below 500 feet will likely remain spotty and localized based on precip rates. Best window of any lowland accumulation remains between 09Z and 17Z.
Outside of that, mountains will continue to get hammered with heavy snow through Friday for dicey travel across the passes.
Precipitation is on track to turn more showery over the weekend before the pendulum swings the other direction for a shift toward above normal temperatures toward the early to middle portion of next week with wet conditions continuing. No forecast updates planned at this time, but we will be monitoring radar, cameras, and spotter reports closely overnight. Previous discussion follows with update to aviation portion. 27

A weak atmospheric river continues in Oregon, providing western Washington with some widespread showers across the area this afternoon. This weak atmospheric river will lift northward later this evening and into Friday morning, allowing for more moisture to funnel in the area, primarily south of Seattle, although showers will still be present across much of the CWA A Winter Storm Warning continues for the Cascades and the Olympics as significant mountain snow continues, on the order of a couple of feet for Snoqualmie and Stevens Pass.

Turning into Friday morning, the forecast gets a bit complex and complicated. Cooler air aloft will push down the snow levels downwards to 500 to 1000 feet, which would allow a rain/snow mix to develop across the region. There is usually the question whether moisture will be present, and guidance does show some moisture from the aforementioned atmospheric river still being around the area (especially in the southern half of the state).
Latest guidance does suggest there could be light accumulations possible on the higher foothills, along with grassy and elevated surfaces. This is a complex situation as local surface conditions and temperatures will be critical factors in what (if any) snowfall accumulations may be present early Fri morning.

Overall: you will likely see snow in the interior (particularly in Puget Sound) Friday morning in some capacity. However, ground temperatures and near surface temperatures are likely to be above freezing, which will result in highly variable surface accumulation. The places that are likely to see any sort of snow that sticks, are places on the higher foothills, which are likely around an inch or two at best. The time frame for this is generally early Fri morning, (4AM-9AM). After that, daytime heating will take over and warm everything up. Shower will decrease throughout the day, and high temps will be in the low 40s. Heavy mountain snow continuing.

The same problem exists for Saturday morning, although there will be less moisture present across the area. Could see a few flakes fly, but otherwise, Saturday will be a drier day with temperatures in the mid 40s as an offshore ridge builds.
Mountain snow will also have gradually subsided by Saturday.

LONG TERM /SUNDAY THROUGH THURSDAY/
Ensembles continue to agree of a warm front will move over the offshore ridge Sunday into Monday, which would bring another round of precipitation over the area. Guidance continues to depict the ridge not being strong enough to keep an atmospheric river from the north out of our area, with lowland rain and a unsettled pattern continuing throughout midweek. A warmer air mass looks to bring up snow levels to 7000 to 8000 feet, along with high temps creeping in the upper 50s, and even lower 60s.

Mazurkiewicz

AVIATION
A strong upper level jet will remain over Western Washington through Friday. Precipitation will continue through tonight, before slowly sliding southwards during the day Friday.
Temperatures will also cool overnight. This will allow for precipitation to transition to snow or a rain and snow mix for most terminal locations, especially across the interior. KPAE remains snow at this time due to the cooler temperatures as of 03z. Although snowfall accumulations are expected to be limited. If rates remain heavy, minor snow accumulations can be expected on paved surfaces, including snow sticking onto airport surfaces. In addition, cigs and vsbys will remain deteriorated through Friday morning with abundant surface moisture and light flow. LIFR/IFR conditions will dominate for most locations between 06z to 15z, with some improvements across northern terminals by mid Friday morning. Cigs will remain MVFR/IFR for the majority of terminals through Friday afternoon. Light E/SE winds will have a light north component into Friday morning, with winds in most locations remain below 6 kts.

KSEA...Light to moderate rain through early tonight. Due to cooling temperatures, rain is expected to transition to rain/snow or snow generally after 07-09z. Snow may stick to airport surfaces if snowfall rates remain heavy enough, particularly during the 10 to 16z period. Otherwise, lingering precipitation will likely transition back to rain generally by 18z. Cigs and vsbys will remain deteriorated through Friday morning, with LIFR/IFR conditions. Cigs will slowly improve to low-end MVFR by late Friday. Light SE winds will likely become light E/NE tonight into Friday AM, remaining below 6 kts. JD

MARINE
A stationary front will remain over the southern coastal waters through the weekend. Precipitation will continue to pass over the waters, with reduced visibilities and ceilings at times. Winds will continue to decrease through the afternoon from yesterday's cold front that passed through. A small craft advisory remains in effect through 5 PM for the Strait of Juan de Fuca for lingering west winds over 20 kt, and the coastal waters through 11 PM for seas above 10 ft. The winds will turn northerly on Friday, with a medium chance on Saturday that gusts exceed 20 kt for the coastal waters. Seas through the weekend will drop and hold around 6 to 8 ft, further decreasing to 4 to 6 ft. A warm front will skirt the outer coastal waters Monday next week, with potential for gusty south winds for the coastal waters, and a few interior waterways. These winds are forecasted to linger into late Tuesday. Seas on Monday will rise to 10 to 12 ft, and linger at those heights through midweek.

HPR

HYDROLOGY
The Skokomish River has crested and will continue to linger in Action Stage. More rain in the forecast through Friday will keep the threat of flooding along the Skokomish Friday into Saturday. With the heaviest precipitation over the Southwest Interior there is also a threat of flooding Friday into the weekend for a few rivers in the Chehalis Basin including but not limited to the Skookumchuck, Newaukum and the Chehalis River from Grand Mound to Grays Harbor. Therefore, a Flood Watch has been issued for those following areas. The flooding threat will ease Sunday into next week for the southern portion of the area. Atmospheric river forecasted to move inland to the north during the first part of next week. If the river ends up a little further south rivers over the northern portion of the area will bear watching the first part of next week.

Felton/Mazurkiewicz

SEW WATCHES/WARNINGS/ADVISORIES
WA...Winter Storm Warning until 5 AM PDT Saturday 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-Olympics.

Flood Watch from Friday morning through Sunday afternoon for Cascades of Pierce and Lewis Counties-Foothills and Valleys of Thurston and Lewis Counties-Foothills of the Western and Southern Olympic Peninsula-Grays Harbor County Coast-Lower Chehalis River Valley-Lowlands of Lewis and Southern Thurston Counties-Middle Chehalis River Valley-Olympia and Southern Puget Sound-Olympics- Willapa and Black Hills.

PZ...Small Craft Advisory until 11 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.