textproduct: Seattle/Tacoma

SYNOPSIS

A broad upper level trough will continue to produce mostly cloudy and cool conditions across Western Washington into Thursday along with chances for light showers over the mountains and along the coast. Drier conditions and a small warming trend are expected Friday into the holiday weekend as the flow aloft becomes first more zonal then southwesterly by Monday. Temperatures will return closer to normal with more chances for sun.

SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/

Fairly widespread stratus persists early this afternoon across the lowlands with a few breaks in the cloud deck noted across the Strait of Juan de Fuca and near Everett. Additional slow improvement with increasing cloud breaks is expected through the afternoon hours, though complete clearing is unlikely. With additional afternoon filtered sunshine, still anticipate high temperatures reaching into the mid and upper 60s across the Puget sound and near 60 along the immediate coast. With nightfall, a return of overnight stratus and drizzle is expected with partial afternoon clearing on Wednesday, overall very similar weather to conditions today. On Thursday into Thursday night...a slightly stronger shortwave will push into British Columbia and drag a weak cool front into Western WA, which will result in enhanced light rainfall chances across the coastal zones and the Olympics, and a deepened marine layer across the Puget Sound for much of the day. Otherwise, seasonably cool conditions will persist.

LONG TERM /FRIDAY THROUGH TUESDAY/

The weather pattern will begin to transition on Friday into the weekend as heights slowly begin to rise in response to strengthening high pressure across the Western US. This will allow for the daily stratus layer to gradually thin out and burn off earlier in the day, and a slow warming of temperatures through the weekend back to near seasonal normals. Additional warming is anticipated heading into next week as high pressure amplifies over the interior West, with temperatures climbing above normal.

Outler

AVIATION

A nearly stationary broad upper level trough over the west coast will maintain northwesterly flow aloft. VFR cigs present over much of W WA this evening although there are isolated patches of MVFR/IFR...mainly locations more prone to lower cigs such as HQM and PWT. These VFR conditions will be brief, as redevelopment of stratus is expected tonight as cigs lower to MVFR /with localized areas of IFR possible/ overnight. Current pattern will continue into Wednesday, with a return to low-end VFR conditions expected to emerge for most terminals in the afternoon. South to southwest winds 5 to 10 kt will continue through the period.

KSEA...VFR conditions with some breaks in the clouds this evening. Those breaks will fill in as cigs begin to lower again tonight with MVFR conditions expected to re-emerge overnight. There is some chance for cigs to lower down into IFR range early Wednesday morning, mainly between 14-17Z, however confidence is not quite there for TAF inclusion. South to southwest winds 5 to 10 kt will continue through the period.

62/18

MARINE

Broad high pressure will continue over the northeast Pacific with low pressure inland, maintaining strong northwesterly winds over the coastal waters, as well as steep, choppy seas up to 10-13 ft with a dominant period of 9 to 10 seconds. This will continue through tonight until winds and seas begin to ease during the day Wednesday. This will be due to a low pressure system forming and moving into the central B.C. coast with a weak frontal system that will move through the coastal waters on Thursday. High pressure will rebuild Friday into the weekend.

Diurnal westerly pushes down the Strait of Juan de Fuca will continue through much of the week and into the weekend. Winds will be rather marginal with wind gusts up to 25 kt tonight, through stronger pushes are expected each day and going into the weekend for additional Small Craft Advisories likely.

62

FIRE WEATHER

Little in the way of fire weather concerns in the week ahead. Upper level troughing maintaining cool and cloudy conditions with high relative humidity values and a slight chance for showers along the coast and mountains on Thursday. Drier, sunnier, and more seasonable temperatures will begin Friday continuing into early next week. Low level onshore flow will moderate daytime minimum RH values and bring in good RH recovery each night.

Felton/62

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory until 5 AM PDT Wednesday for Central U.S. Waters Strait Of Juan De Fuca-Coastal Waters From Cape Flattery To James Island Out 10 Nm-Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm-East Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory until 6 PM PDT Wednesday 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.