textproduct: Seattle/Tacoma

SYNOPSIS

An upper-level trough offshore will push inland over the weekend, bringing cooler temperatures to the area and additional chances of showers. Troughing will persist through early next week, allowing for temperatures to trend just below to near normal with continued PoPs. Drier conditions favored midweek onward.

SHORT TERM /TODAY THROUGH SUNDAY/

The upper-level pattern can be characterized by an upper-low over the NE PAC and stout ridging centered over the SW US. At the surface, low-level onshore flow is ongoing across W WA with marine stratus this morning. Satellite imagery already indicates some scattering across portions of SW WA this morning, which will further allow the stratus to retreat back to the coast by this afternoon with help of diurnal heating. Today, subtle ridging is amplifying across the region, bringing a brief spell of above average temperatures. Interior highs are forecast to range between the upper 70s to mid 80s. Coastal areas of course cooler in the lower to mid 60s. Dry conditions again tonight but the aforementioned upper-low will begin to show signs of progression as it becomes ingested within the mean flow. Marine stratus on track to redevelop overnight into Saturday morning under continued onshore flow. Min temperatures will fall between the lower to upper 50s.

The upper-low will finally move inland on Saturday as PoPs return into the forecast, primarily over the coast and mountain areas. Models have rain showers straggling into Sunday as well as upper-troughing becomes the main influence across W WA. This pattern favored onshore flow as reoccurring spells of marine stratus and slightly below-normal temps trend throughout the weekend with highs 70s.

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LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/

Looking forward into next week, upper level troughing remains the dominant influence across the area as several systems move down from the Gulf of Alaska. Some model solutions show the upper level high over the Four Corners region retrograding westward, which may allow conditions to trend drier and warmer towards the second half of the week. Otherwise temperatures generally remain around climatological normals.

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AVIATION

Southwest flow aloft is expected over Western Washington today with an upper ridge centered east of the region and an upper trough offshore. The low level flow is onshore and will increase today. Widespread IFR/LIFR stratus across much of the lowlands will burn back toward the immediate coastline by early this afternoon. MVFR ceilings will develop most areas west of the Cascades overnight into Saturday morning.

KSEA...IFR/LIFR stratus will lift and scatter toward 18Z. Increasing onshore flow will lead to a deeper marine layer tonight into Saturday morning with MVFR ceilings persisting into at least mid- afternoon Saturday. Surface winds W/SW rising to 7 to 10 knots becoming southerly tonight. 27

MARINE

Low level onshore flow continues today with strongest winds through the central/east Strait of Juan de Fuca - a Small Craft Advisory is in effect. A frontal system will stall offshore on Saturday then shift inland late Sunday. Another front will cross the waters on Tuesday. 33

FIRE WEATHER

More benign fire weather conditions expected today through early next week. The low offshore will finally make its way over the region. This will result increased onshore flow with cooler temperatures and shower chances through the weekend into the first part of next week easing fire weather concerns. Additional thunderstorms are not likely but can't be ruled out at this time.

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SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory from 5 PM this afternoon to 5 AM PDT Saturday for Central U.S. Waters Strait Of Juan De Fuca- East Entrance U.S. Waters Strait Of Juan De Fuca.