Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000 FXUS66 KSEW 142210 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 315 PM PDT Thu Jun 14 2018 .SYNOPSIS...
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After some clearing tonight, a weak upper level low will move south through the area Friday night. The low will stall over Oregon through about Monday, giving a chance of showers or thunderstorms in the Cascades each day. Temperatures will rise beginning Sunday, with highs in the 80s, possibly near 90 mid week.
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&& .SHORT TERM...
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The cumulus field over most land areas this afternoon will dissipate this evening, giving mostly clear skies overnight. Marine stratus is likely to form on the coast and spread part way inland late tonight. Lows tonight will be around 50. An upper level low will approach from the north Friday and move through Western Washington into Oregon by Saturday morning. Some shower activity will develop in the mountains. On Friday evening there could be a few showers in the southwest interior as well. Isolated thunderstorms in the Cascades are a possibility. Weak low level onshore flow will keep some low level moisture in the area at least in the morning hours. There should be some sun in the afternoon, especially in the lowlands. Highs Friday will be 65-70. The upper level low is forecast to remain in Oregon through about Monday. Return flow over Washington will bring moisture to the Cascades from the east each day, with a chance of showers and isolated thunderstorms each afternoon and evening. Showers could drift west over some of the lowlands on Saturday. Sunday should be dry everywhere except for the chance of showers in the Cascades. High temperatures will be well into the 70s on Saturday, and well into the 80s on Sunday. By Monday the shower threat is pretty minimal in the Cascades. Highs will be in the 80s, with some low 90s possible in spots. Burke .LONG TERM...The upper low, now with less punch but still able to spawn the occasional shower, will probably remain relatively close Tuesday through Thursday. The GFS and Euro are in broad agreement, moving the low into Idaho Tuesday and Wednesday, then moving it a bit closer on Thursday. Have kept a dry forecast for Tuesday and Wednesday, and introduced showers in the Cascades Thursday. Highs will be in the 80s over inland areas all three days, with low 90s possible. Cooling is possible Thursday, especially on the coast where onshore flow could lower temps into the 60s. Burke
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&& .AVIATION...
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A broad upper trough will be over the area tonight and Friday with light northwest flow aloft. At the surface, onshore flow will continue. The air mass is moist and slightly unstable. Ceilings will be generally 5000-8000 feet through this evening. MVFR low clouds will develop across a good portion of the area late tonight and Friday morning. The low clouds will lift and scatter on Friday with 5000-8000 foot ceilings again in the afternoon. KSEA...Ceilings 5000-8000 feet through most of tonight. MVFR low clouds should redevelop Friday morning. Westerly wind 4-8 knots will become northerly this evening. Schneider
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&& .MARINE...
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Onshore flow will continue for the next several days with high pressure offshore and lower pressure east of the Cascades. The onshore flow is expected to weaken slightly and turn a bit more northwesterly this weekend. Small craft advisory strength west winds are likely in the Central and Eastern Strait of Juan de Fuca most evenings into the first half of next week. Small craft advisory strength northwest winds are also expected at times for the Coastal Waters Friday through Sunday. Schneider
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&& .SEW WATCHES/WARNINGS/ADVISORIES...
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WA...None. PZ...Small Craft Advisory from 2 PM Friday to midnight PDT Friday night for Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm. Small Craft Advisory from noon Friday to 6 AM PDT Saturday 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 from 6 PM this evening to 3 AM PDT Friday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.
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&& $$ www.weather.gov/seattle

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