textproduct: Seattle/Tacoma

SYNOPSIS

A dry and cloudy day expected across the area today. The next frontal system will arrive on Wednesday, bringing lowland rain, mountain snow, and gusty winds to western Washington. Showers will linger across the mountains on Thursday before a drier and warmer pattern sets up over the area Friday and persists over the weekend.

SHORT TERM /TODAY THROUGH THURSDAY/

High clouds continue to stream in overhead early this morning under zonal flow aloft. This will largely limit any widespread fog development across the area and will help keep morning lows a couple degrees warmer than yesterday (mainly in the low to mid 30s). A few, isolated spots may still see some patchy fog this morning, especially where cloud cover is thinner, but primarily expect this to be confined to areas south of the Sound. Conditions will remain dry and cloudy across western Washington today, with zonal flow expected to turn more southwesterly this afternoon ahead of the next system arriving on Wednesday. Afternoon highs will be a couple degrees warmer than Monday and will top out in the low to mid 50s across majority of the area.

The next frontal system will move across the area on Wednesday, bringing the next round of lowland rain, mountain snow, and gusty winds to western Washington. Winds will start to increase along the coast and the eastern Strait by early Wednesday morning. The strongest winds are expected to be along the coast and for areas from Whidbey Island northward, where gusts between 35-45 mph will be possible. Elsewhere, expect winds to be breezy, with winds gusts ranging between 25-35 mph. Winds will remain elevated through the morning hours, before easing through the afternoon. The lowlands will see a steady round of rain spread across the interior through the morning, with most likely amounts across the interior ranging from 0.25 inches from more shadowed locations to 0.50 inches. The coast will see the highest amounts of rain- roughly half an inch to an inch. Snow levels will start out below pass level on Wednesday and rise to 4000-4500 ft through the day, before falling back below pass levels by early Thursday. At this time, snow accumulations at the passes generally look to remain between 4-8 inches, with latest probabilistic guidance only indicating roughly a 10-20 percent chance of snowfall amounts exceeding 8 inches.

The parent low pressure system will move inland over northern OR/southern WA on Thursday. Wrap-around moisture from this system will likely keep light snow shower activity going across the Cascades, though expect to see showers gradually taper as the day progresses. Across the lowlands, expect conditions to dry out and for clouds to scatter for some afternoon sun breaks. Afternoon high temperatures will be in the mid 50s.

LONG TERM /THURSDAY NIGHT THROUGH MONDAY/

Ensembles favor a warmer, drier trend commencing Friday and persisting through the weekend as upper level ridging builds into western Washington. While a weak weather system may attempt to brush the North Coast on Friday, the building ridge will shift the incoming storm track northward into British Columbia. This will keep western Washington dry through the weekend and into early next week. Temperatures will trend above normal and look to warm a few degrees each day, with afternoon highs potentially topping out in the mid to upper 60s by Monday.

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AVIATION

Zonal flow aloft today before turning more southwesterly tonight into Wednesday morning. Mid-high level clouds are streaming overhead, limiting widespread fog development. Patches of fog are possible this morning near river valleys like the Chehalis and parts of South Sound as well. VFR is observed area wide and should remain well into the day and tonight. Widespread rain will enter early Wednesday morning with the return of MVFR/IFR cigs. Can't rule out isolated instances of LIFR as well. Northerly surface flow becoming southerly and breezy overnight into Wednesday.

KSEA...VFR conditions with passing high clouds. North surface winds becoming more southerly after 00z. VFR conditions through Tuesday night before low clouds increase into early Wednesday morning with rainfall.

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MARINE

Surface high pressure today with light winds. A sub 995 mb low pressure system will start to approach the region Tuesday night- Wednesday morning with increasing southerlies over much of the waters. A Gale Watch has been issued for the coastal waters and East Entrance as hi-res guidance (REFS and HREF) indicate a 50-70% chance of gusts exceeding 35 kt late Tuesday night into Wednesday morning. SCA advisory may be needed for other inland water zones during this time as well.

Broad high pressure will redevelop on Thursday and into the end of the week, bringing generally benign marine conditions to the waters.

Coastal seas remaining 3 to 5 feet throughout Tuesday. Seas will then build up to 9 to 11 feet Wednesday morning. Seas will remain elevated into Thursday before decreasing on Friday and into the weekend, back down to 3 to 5 feet.

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HYDROLOGY

River flooding is not expected over the next 7 days.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Gale Watch from late tonight through Wednesday morning for East Entrance U.S. Waters Strait Of Juan De Fuca.

Gale Watch from late tonight through Wednesday 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.