textproduct: Seattle/Tacoma

SYNOPSIS

Onshore flow will lead to mild weather across western Washington this week and into the weekend. Expect a slight chance of showers in the Olympics and northern Cascades. Drier and warmer conditions are forecast early next week as high pressure builds over the western US.

SHORT TERM /TODAY THROUGH FRIDAY/

A weak/dry front is passing through western WA early this morning with increasing onshore flow. This onshore push will bring cooler conditions to the region and keep temperatures closer to average. Expect highs in the lower to mid 70s in the interior with 60s along the coast. Highest winds will be through the strait.

Low pressure will remain over B.C./Alberta on Thursday with zonal flow over WA. Ongoing onshore flow will result in morning clouds with afternoon sunbreaks. Temperatures will track close to seasonal averages.

On Friday, the low will shift W/SW and offshore and the flow aloft will become more southwesterly. A moisture tap will bring a few high-based showers to the Olympics and northern Cascades. The chance for wetting rains is low, though. The chance for thunderstorms is low too (less than 10 percent). 33

LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/

Low pressure will linger offshore through the weekend, keeping western WA slightly cooler and mild. There's a slight chance of showers again in the Olympics and northern Cascades although total rainfall is low. The low ejects northeastward and heights build early next week as strong high pressure forms over the western/central CONUS. Warmer temperatures are expected with highs reaching the lower to mid 80s in the interior on Monday and Tuesday. The coast will remain cooler and in the 60s due to NW winds. 33

AVIATION

Increased westerly flow as a weak cold front moves through W WA is allowing stratus to fill back into the region. MVFR/IFR conditions are being observed along the coast with MVFR conditions spreading inland, becoming widespread by 10-12Z Wed. Periods of IFR or lower conditions cannot be ruled out area- wide, though the highest likelihood is along the coast and into the Kitsap Peninsula. Expect cigs to scatter and improve to VFR behind the frontal passage after around 18-21Z Wed, with the exception of over the central Puget Sound area where post- frontal convergence will keep lower cigs and place and perhaps squeeze out some light showers or drizzle for another few hours. There's a 70-90% chance MVFR or lower cigs return to the coast by 04-06Z Thu around and north of KUIL, and a 40-60% chance along the rest of the coast after 06Z Thu. There's also a 20- 40% chance of MVFR cigs returning inland after 09Z Thu with chances peaking around and after sunrise (12-16Z).

Relatively light winds less than 10 kts expected, west to northwest for locations west of the Puget Sound and west to southwest east of the Puget Sound. Winds for locations east of the Puget Sound shift more northerly after 16-18Z Wed.

KSEA...MVFR cigs expected to return after around 11-13Z Wed with a 20-35% chance for periods of IFR cigs, mostly likely between 13-17Z Wed. A slow lift is expected with low-end VFR conditions possible after around 21Z Wed. Convergence behind the front look to keep ceilings in the picture through much of the day.

Light south to southwest winds 5 kt or less will likely turn to west to northwest after 19-21Z Wed.

MARINE

Onshore flow will prevail through the remainder of the week and weekend. Highest wind/waves will be found through the Strait of Juan de Fuca during the afternoon and evening hours. Gales or Small Craft Advisory westerly winds are expected through the strait each day. 33

FIRE WEATHER

Onshore flow will lead to near average temperatures and higher humidities, thus keeping the overall fire weather danger low. Dry and warmer conditions are forecast early next week although minimum humidities will not reach critical thresholds.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Gale Warning until 8 AM PDT this morning for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.

Gale Warning from 2 PM this afternoon to 5 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 3 AM PDT early this morning for Admiralty Inlet.