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/

No significant changes to the short/long term AFD this morning. -HPR

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

A mix of VFR and MVFR cigs this morning. Expecting widespread VFR for all terminals after 19Z, continuing into Saturday morning. Southerly winds this morning, will transition northerly this evening. Calm to light northerly winds overnight. Visibility reductions possible (20% chance) Saturday morning across portions of the southern interior.

KSEA...Currently VFR at the terminal this morning, but have opted to trend it MVFR through 19Z due to low clouds lingering within the vicinity. Some high-res guidance is also favoring the low clouds persisting this morning. As a result, may see some cigs bouncing around this morning, until they lift to VFR this afternoon. VFR conditions will continue into Saturday. SSE winds this morning will transition more SSW this afternoon around 6-8 kt. Winds switch northerly this evening after 03Z around 4-6 kt.

29

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...None.