textproduct: Seattle/Tacoma

SYNOPSIS

Dry and mild weather prevails through Thursday with warmer temperatures on Friday. The next disturbance shifts over the area late Friday through Saturday, bringing cooler and cloudy conditions along with showers and thunderstorms. High pressure returns early next week, bringing back dry and warmer conditions.

SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/

There is weak upper level troughing over western WA today along with low level onshore flow. The result is near-normal conditions with temperatures close to average. An upper level low will spin off B.C on Thursday while a front stalls offshore. Models bring rain to SW B.C. but keep western WA dry. The upper low makes very little movement on Friday and precipitation is aimed to our north again. The air mass is a little warmer, though, with higher heights and a building ridge to the east. Forecast highs will reach the lower to mid 80s in the interior - a few degrees warmer than average. The coast will see temps in the 60s and 70s. Overnight lows will track in the 50s to help keep the overall Heat Risk category at Minor. 33

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Cooler, cloudier and wetter conditions are forecast for Saturday as the upper level low tracks inland and over WA. The north coast and north Cascades have the highest probabilities of seeing wetting rain through the day. The air mass will be slightly unstable too and thunderstorms chances have increased for the north interior and northern Cascades. Showers with a convergence zone are expected Saturday afternoon/evening with post-frontal onshore flow increasing. It'll be windy too with S/SW winds gusting to 20-30 MPH across most lowland areas.

The upper level low exits to the N/NE on Sunday with a few lingering showers in the Cascades. High pressure will shift inland early next week leading to warmer conditions. Interior lowland temperatures will reach the 80s to lower 90s again. 33

AVIATION

Southwest flow aloft with low level onshore flow will persist through Thursday. Widespread VFR conditions through afternoon and evening. An additional round of low stratus expected again early Thursday morning particularly along the coast, strait and south Puget Sound/Kitsap Peninsula.

KSEA...VFR ceilings will linger through the forecast period. morning. LAMP and REFS guidance showing around a 20% chance of MVFR ceilings Thursday morning, with most likely scenario keeping stratus well to the west and south of the terminal. NW winds 5-10 kt will ease to 4-6 kt during the evening then shift to the SW Thursday morning, 71% of REFS hires members show this occuring by 5 AM. Another wind shift is possible to the NW late in the afternoon or early evening.

MARINE

High pressure remain over area waters through Friday with low-level onshore flow. A SCA remains in effect for the central/eastern Strait of Juan de Fuca Wednesday evening through early Thursday morning. The next disturbance will reach the waters Friday night into Saturday with the potential for more headlines particularly with a strong westerly push through the Strait of Juan de Fuca. Seas over the coastal waters are expected to remain in the 4 to 6 foot range into early next week.

FIRE WEATHER

Near-normal conditions are forecast through Thursday. On Friday, expect warmer and drier weather with min humidities reaching the 30s in the Black Hills and SW Interior lowlands, SE Puget Sound lowlands, and Cascade valleys. A system on Saturday will bring wetting rain to the north coast and north Cascades (with a chance of thunderstorms). It will be windy with gusts near the crest in the 30-40 MPH range. However, with the wetter and cooler conditions, min RHs will not reach critical thresholds. Warmer and drier weather early next week will keep the fire weather threat elevated (especially next Tuesday and Wednesday). 33

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory from 7 PM this evening 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.