textproduct: Seattle/Tacoma

SYNOPSIS

Troughing developing over the area will continue into this weekend, bringing unsettled conditions and cooler temperatures to the region. Ridging looks to rebuild through the first half of next week for a slow warming trend.

SHORT TERM /TODAY THROUGH SUNDAY/

An upper level trough over the region will continue to bring onshore flow, cooler temperatures, and unsettled weather to western Washington over the next couple of days. It'll deepen today as its associated upper-low forms off the BC coast and positions offshore by this evening. As a result, light shower activity is possible over the Olympic Peninsula tonight but conditions are to remain mostly dry across the area. Highs today will top out in the 60s to near 70 F with overnight lows in the 50s.

The upper-low will traverse across the region on Saturday, bringing widespread rain, showers and a 15-20% chance for thunderstorms. The highest probability for lightning is over the Olympics and southwest interior according to the NBM. It'll hang around through Sunday with continued precipitation chances but the thunderstorm threat will diminish with probabilities less than 10%. High temperatures ranging between the 60s to near 70 F and lows mainly in the 50s for both Saturday and Sunday.

LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/

Conditions are favored to trend drier Sunday night as the low center crosses east of the Cascades. Can't rule out lingering showers over the mountains. An upper level ridge will begin to build offshore on Monday, introducing a slow warming trend through midweek. Some ensembles suggest weak troughing Tuesday-Thursday that could bring some PoPs to the region, but for now, looks like dry and warm conditions will manifest.

AVIATION

Northwesterly flow aloft becoming westerly this morning and southwesterly this afternoon as an upper level low moves south near 130W. Weak onshore flow in the lower levels.

VFR ceilings early this morning. Widespread MVFR ceilings developing 13z-16z lasting into early afternoon. VFR all areas by mid afternoon with VFR ceilings continuing into Saturday morning.

KSEA...MVFR ceilings developing 14z-16z with ceilings lifting back to VFR 20z-22z. VFR ceilings continuing into Saturday morning. South wind 4 to 8 knots becoming southwest this afternoon. Wind switching to northerly 4 to 6 knots around 03z. Felton

MARINE

High pressure over the waters will weaken today. A weak system will move through the offshore waters into Oregon tonight and Saturday. High pressure will rebuild over the coastal waters Sunday and remain through Tuesday.

Possible small craft advisory winds in the Central and Eastern Strait of Juan de Fuca Saturday night.

Seas 5 to 7 feet today and a little choppy. Seas subsiding to 3 to 5 feet Saturday with 3 to 5 foot seas continuing into the first half of next week. Felton

FIRE WEATHER

A return to onshore flow will maintain cooler and more moist conditions across western Washington through the weekend. Light precipitation is likely into Saturday as another weak system moves over the region with a slight chance (15-20%) of thunderstorms. Conditions are expected to gradually warm and dry into next week, though fire weather concerns remain low at this time.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory until 5 AM PDT early this morning for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm-Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm.