textproduct: Seattle/Tacoma

SYNOPSIS

Upper level ridge building over the area today will remain in place through the weekend. The ridge will drift east Monday. Upper level trough moving by to the north Monday night and Tuesday will induce a marine push. Dry northwesterly flow aloft Wednesday through Friday with an upper level low well southwest of Western Washington.

SHORT TERM /TODAY THROUGH MONDAY/

Satellite imagery shows cloud cover along the north coast and over the Northwest Interior. Fog has formed in the last couple of hours in the Southwest Interior and Lower Chehalis Valley. Temperatures at 3 am/10z were in the mid 30s to mid 40s.

Dry weather in the short term with an upper level ridge building over the area today and tonight. Patchy fog this morning will dissipate quickly after sunrise. Frost advisory for the Southwest Interior and Lower Chehalis Valley will expire at 9 am. The ridge will remain in place Sunday then slowly drift east Monday. Upper level flow becoming southwesterly later tonight into Monday. High clouds embedded in the flow aloft moving through Sunday and Monday. Low level flow turning offshore today. Offshore flow continuing through Sunday night with the low level flow becoming light Monday. Warming trend through Monday. Highs today in the mid 50s to lower 60s, Sunday and Monday 60s to lower 70s. Lows in the 40s. Felton

LONG TERM /MONDAY NIGHT THROUGH FRIDAY/

Classic marine push scenario Monday night into Tuesday. Upper level shortwave riding by to the north inducing an increase in low level onshore flow. Much cooler Tuesday with highs in the lower to mid 50s. Next upper level trough will go by well to the north and east Wednesday. Dry northwesterly flow aloft Wednesday through Friday with an upper low off the Northern California coast remaining stationary. Highs recovering into the mid 50s to lower 60s Wednesday through Friday. Lows in the 30s through Thursday morning, mid 30s to lower 40s Friday morning. Could see another round of frost advisories for the Southwest Interior and Lower Chehalis Valley Wednesday and Thursday morning.

AVIATION

Westerly flow aloft will continue today as upper ridging centered south of the region builds northward. There is low confidence for lows clouds forming in the morning in some spots such as OLM, HQM, and BLI (would most likely be MVFR if they do form) but otherwise conditions will remain VFR through the TAF period. Winds will shift to the north, increasing to 6-12 kts this afternoon.

KSEA...VFR is expected through the TAF period. Probability for MVFR clouds this morning remain low at the terminal, though may form as far south as Tacoma. Northerly winds will increase to 8 to 12 knots this afternoon after around 21Z, continuing at this speed into tonight.

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MARINE

High pressure will remain over the waters this weekend while a thermally induced trough expands northward along the Oregon coast. This will shift the flow northerly or weakly offshore. Onshore flow resumes early next week as a frontal system passes to the north. A strong westerly push is possible along the central and eastern Strait of Juan de Fuca Monday night into Tuesday.

Seas across the coastal waters will build towards 7-10 ft Tuesday into Wednesday.

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HYDROLOGY

No river flooding the next 7 days.

SEW WATCHES/WARNINGS/ADVISORIES

WA...Frost Advisory until 9 AM PDT this morning for Foothills and Valleys of Thurston and Lewis Counties-Lower Chehalis River Valley-Lowlands of Lewis and Southern Thurston Counties-Middle Chehalis River Valley-Olympia and Southern Puget Sound-Willapa and Black Hills.

PZ...None.