Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000 FXUS66 KSEW 102308 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 308 PM PST Sun Dec 10 2017 .SYNOPSIS...A strong upper ridge will maintain dry and stagnant conditions across Western Washington through Wednesday. The ridge will break down by Thursday with rain returning Thursday night and Friday. Wet weather will continue through the weekend with strong moist flow over the area. && .SHORT TERM...Fog was limited today due to dense cirrus clouds that passed before sunrise. As a result, there was less radiational cooling and therefore higher dew point depressions. The visible satellite shows some patchy clouds or fog over Hood Canal otherwise the rest of the region is sunny. Temperatures are mainly in the 40s with 50s along the coast. Looks like Quillayute, KUIL, hit 59 degrees which is a new daily record high. Skies should remain clear tonight with fog reforming around Puget Sound. The dry conditions, light winds and poor mixing has lead to stagnant conditions. This may result in deteriorating air quality. An Air Stagnation Advisory remains in effect for the interior lowlands - burn bans are possible. There`s a slight change in the pattern on Monday when a shortwave trough clips the NW portion of the ridge, slightly flattening the heights over W WA. This features is dry but we could see a bit more mixing with a weaker low level inversion. The strong ridge will rebuild over the region Tuesday and Wednesday for similar conditions...aka dry. The biggest forecast challenge will again be fog coverage and temperatures. 33 .LONG TERM...It looks like Thursday will be our last dry day of this stretch as the ridge will start to break down. We should see rain returning by Thursday night or Friday as a trough moves in from the west. The models have been waffling on the exact timing of this system and it`s now slightly slower compared to yesterday`s (faster) solutions. Moist west to northwest flow will continue trough the weekend for more wet weather with snow in the mountains. 33 && .AVIATION...A strong upper level ridge will remain over the region for sly flow aloft. The low level flow will be light offshore. Expect areas of LIFR CIGs/VSBYs to develop over the interior lowlands overnight, continuing thru at least Monday morning. KSEA...Still expecting VFR conditions to prevail through much of tonight. A few hours of dense fog is anticipated Monday morning. Light northerly winds will become light and variable Monday afternoon. && .MARINE...Lower pressure offshore with higher pressure inland will result in light easterly or offshore flow through midweek. Expect a cold or occluded front to move across the area late Thursday night or early Friday. This will cause the flow to become onshore and strengthen. && .HYDROLOGY...River Flooding is not expected for the next 7 days. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...Air Stagnation Advisory until noon PST Monday for Admiralty Inlet Area-Bellevue and Vicinity-Bremerton and Vicinity- East Puget Sound Lowlands-Eastern Strait of Juan de Fuca- Everett and Vicinity-Hood Canal Area-Seattle and Vicinity- Southwest Interior-Tacoma Area-Western Skagit County- Western Whatcom County. PZ...Small Craft Advisory until 2 AM PST Monday 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. Small Craft Advisory until 9 AM PST Monday for Coastal Waters From Cape Flattery To James Island Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm-West Entrance U.S. Waters Strait Of Juan De Fuca. && $$ is the U.S. government's official web portal to all federal, state and local government web resources and services.