textproduct: Seattle/Tacoma

SYNOPSIS

Onshore flow will persist through the week, keeping western Washington cooler with mixes of clouds and sun, as well as slight chances of showers over portions of the Olympics and Cascades. High pressure will build under a ridge early next week, with high temperatures climbing back into the low 80s for portions of the interior.

SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/

A pretty persistent onshore pattern continues across western WA. A weak front/trough continues to move east of the region, with cloud coverage holding on in the interior on satellite this afternoon. The cloud coverage is dissipating on the coast/north interior, with some cloud breaks delayed to late afternoon/evening. Temperatures will stay cool with highs in the 60s to low to mid 70s, with lows in the 50s through much of the short term as the onshore pattern continues. Thursday in this period appears the best day to see sunshine in the afternoon, as the onshore gradient weakens some. The overall pattern is dry, but with some forced mountain ascent with limited (but sufficient moisture), a couple showers in the Olympics and Cascades can't be ruled out this afternoon, and Friday.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Onshore pattern will continue Saturday with a trough beginning to dip south into the Pacific, and moving onshore Sunday. Once again, a few showers will be possible Saturday and Sunday for portions of the mountains as a front drives through under the trough. Cloud coverage largely holds on through late Sunday, as the trough moves inland. Ensembles show a brief ridge building in between troughs on Monday and Tuesday. There is some disagreement as to how sharp (or broad) the trough offshore will be (which may lead to some tweaks into the next week forecast as the models get closer) but a brief warmup on Monday and Tuesday appears likely. Highs these days will climb back into the low 80s across most of the central/south interior, but there is only a 10-30% chance of Moderate (Orange) HeatRisk. Cooling off on Wednesday remains a question as to how quickly the next trough offshore moves inland.

HPR

AVIATION

This morning holds more MVFR/IFR ceilings as stratus is present across most of the area. Ceilings are expected to improve to VFR behind a front between 18Z-21Z. Winds will turn northerly this afternoon. There is a 60-80% probability for at least MVFR ceilings to return to the coast starting at 08Z Thursday, and a 15-25% probability inland near Seattle.

West to southwest winds will turn more north in the late afternoon/early evening today.

KSEA...MVFR ceilings will continue through this morning while gradually improving to VFR. Smoke aloft is possible due to regional wildfires. Convergence behind the front look to keep ceilings in the picture through much of the day.

Southwesterly winds turn northerly this afternoon and remain near 4 to 8 knots, easing again overnight. AH

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/AH

FIRE WEATHER

The current onshore pattern will continue through next weekend, which will lead to continued periods of excellent moisture recoveries (RH values) next few mornings. A ridge and high pressure pattern appear likely to briefly build into the region Monday and Tuesday next week. While the onshore pattern will largely remain in place with light winds, warmer daytime temperatures and clear skies will likely lead to RH values dipping into the 30s and 20s, with the lowest values in the south interior and Cascades. This will allow dry fine fuels to continue to dry, and so piles of dead fuels, or dry grass/shrub areas may become susceptible to fire starts Monday and Tuesday with elevated fire weather conditions.

HPR

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Gale Warning until 5 AM PDT Thursday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.