textproduct: Seattle/Tacoma

SYNOPSIS

A frontal system is moving through the area this afternoon, bringing rain and some mountain snow. Conditions clear up for the early part of the week, with another system forecast to arrive Tuesday night into Wednesday. Unsettled conditions are expected to linger into the late week before drying out again for the weekend.

SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/

Convergence zone activity will continue this evening behind a westerly push through the Strait of Juan de Fuca. The mountains will receive some snow as snow levels drop later tonight and into Monday morning. Overnight lows will be cold, with upper 20s from Olympia south through the Chehalis Valley. Expect lows around 32 to 35 degrees in the Seattle metro area. Lingering moisture and cold temperatures are likely to produce frosty conditions by early tomorrow morning, with the most favored areas being from Olympia south.

Skies clear into Monday and temperatures only get back into the upper 40s and low 50s with the colder start to the day. Zonal flow aloft sets up late Monday into Tuesday. A brief period of offshore flow is still forecast for Tuesday afternoon, with drier than normal relative humidity expected to accompany it.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

A broader area of low pressure drops down from the Gulf of Alaska on Wednesday, bringing another round of rain and mountain snow. This system will also be a bit breezier, with the favored location for stronger southerly wind gusts being along the coast and through portions of the east Strait of Juan de Fuca and northern inland waters. Snow levels start off lower Wednesday morning, climbing above pass level into the afternoon.

Rain showers become scattered on Thursday as the trough meanders to the southeast. High pressure looks to form off the OR/CA border into Friday, keeping precipitation to the north of the area into the weekend. Temperatures are expected to rebound over the weekend into the upper 50s and low 60s under clear skies.

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AVIATION

A band of heavier showers continues to spread south through the central Puget Sound terminals this evening as stronger onshore flow continues behind the passing front. While ceilings are generally trending mostly to VFR outside of this band of heavier showers, a mix of conditions will continue to develop across the region with local IFR conditions around KPAE and in the south sound. Meanwhile gusty northerly winds above the line of showers and southerly winds to the south of it. Expect this band to eventually fade out late tonight, for a return of light winds to most of the interior. With light winds and residual low-level moisture, there's an increased risk for a window of low MVFR to IFR ceilings early Monday morning. This is particularly the case for more sheltered locations as mid and high clouds clear. That said, low clouds are likely to clear out mid to late Monday morning with northerly surface winds returning for most terminals.

KSEA...Expect mostly VFR conditions after 06z through the first part of the night with winds gradually easing and becoming a bit variable. With decreasing mid/high clouds and light winds, paired with the residual moisture, there's an increased chance of low MVFR ceilings around 10-14z Monday morning. Expect gradual clearing of low clouds and light winds through mid morning, with VFR conditions and a return to northerly surface winds by early Monday afternoon.

MARINE

A cold front pushed through the waters. Gusty winds will decrease this evening in the northern inland waters/Strait of Juan de Fuca areas and coastal waters. Seas have reached 8-12 ft, with the highest being in the outer coastal waters. Seas will ease Monday morning below 10 ft through Tuesday.

Weak high pressure will build behind the system on Monday. High pressure will weaken on Tuesday ahead of a stronger system that is expected to move over area waters on Wednesday. The cold front is expected to move over the waters Wednesday morning with the associated upper level low following behind Wednesday evening into Thursday. Currently guidance is highlight a moderate to high chance (50-80%) of small craft winds for the coastal waters, portions of the Strait of Juan de Fuca, Northern Interior Waters, and Admiralty Inlet. In addition, there is a small chance (25-35%) for gale winds in the East Strait. Latest guidance has also backed off slightly on the waveheight on Wednesday and is suggesting seas will peak around 8-11 ft. High pressure will build again on Thursday and Friday with seas remaining below 10 ft.

29/HPR

HYDROLOGY

No river flooding is expected over the next 7 days.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory until 9 PM PDT this evening for West Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory until 5 AM PDT Monday for Northern Inland Waters Including The San Juan Islands.

Small Craft Advisory until 8 AM PDT Monday 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.