textproduct: Seattle/Tacoma

SYNOPSIS

A weak upper trough will approach Western Washington today then settle over the area into early next week. This will lead to cooler temperatures, increased cloud cover, and occasional chances for mountain showers and coastal drizzle.

LONG TERM /SATURDAY THROUGH TUESDAY/

Upper troughing is expected to dig southward offshore over the weekend. This will lead to some modest height increases over Western Washington. The low level flow will remain onshore, but will relax somewhat. This should give interior areas a slight warming trend and less morning stratus while coastal areas probably won't see much of benefit. The forecast picture still remains somewhat murky as we move into early next week. The ensembles remain split with the Euro suite favoring lowering heights and better chances of precip while a majority of the GFS ensembles maintain higher heights and drier/warmer conditions. Current forecasts for Monday and Tuesday reflect the NBM 50th percentile forecasts which basically take the middle ground with low end shower chances and temperatures a smidge above normal.

AVIATION

Southwesterly flow aloft with upper level trough offshore reaching the area Thursday. Onshore flow in the lower levels.

Low end MVFR/IFR ceilings along the coast and over the Lower Chehalis Valley. Leading edge of the stratus near KPWT at 10Z. Stratus continuing to move east this morning reaching the Central Puget Sound 12-13Z. Mostly IFR ceilings with the stratus in the Central Sound with the lower terminals ceilings near 1000 feet. The layer is shallow and will dissipate back to the coast 17z-19z. Mostly clear skies this afternoon. Stratus forming again along the coast early this evening with MVFR ceilings. Stratus moving inland a little faster tonight with MVFR ceilings reaching the Central Puget Sound 08z-10z.

KSEA...Stratus reaching the terminal 12-13z with IFR ceilings and possible slight visibility restrictions. Stratus dissipating around 17z. MVFR stratus returning to the terminal around 09z early Thursday morning. Southwest wind 6 to 10 knots. Felton

MARINE

Surface high pressure centered offshore with lower pressure inland through Friday. The high will build over the waters during the weekend. A weakening front will reach the area Monday.

Diurnal westerly pushes through Strait of Juan de Fuca are expected each evening, with the strongest of these tonight. Small craft advisory is in effect for tonight with possible small craft advisory westerlies in the evening Thursday into the weekend.

Small craft advisory for the outer coastal waters due to seas remaining generally 8 to 10 ft with dominant periods remaining 8 to 10 seconds through at least Thursday night. Northwesterly winds 20 to 25 knots today will ease slightly tonight into Thursday. Felton

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory from 6 PM this evening to 6 AM PDT Thursday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory until 6 AM PDT Friday 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.