textproduct: Seattle/Tacoma

SYNOPSIS

Upper level ridge over Western Washington today weakening Monday. Upper level trough moving by to the north Monday night into Tuesday inducing a marine push Monday night. Upper level ridge well offshore with upper level low off the Northern California coast giving the area dry northwesterly flow aloft wednesday through Friday. Upper level trough moving down from the north approaching the area next weekend.

SHORT TERM /TODAY THROUGH TUESDAY/

Satellite imagery shows high clouds over Western Washington this morning. The cloud cover has prevented any fog from forming. Temperatures at 2 am/09z were in the 40s.

Upper level ridge over the area today. Southwesterly flow aloft will keep high clouds moving through Western Washington. Low level flow offshore. This will push high temperatures into the 60s and lower 70s.

Upper level ridge remaining in place tonight into Monday with the ridge weakening Monday. Low level offshore flow weakening overnight with light low level flow Monday becoming onshore in the afternoon. With ocean water temperatures between 50 and 52 degrees this switch to onshore winds will cool the coast down into the mid to upper 50s. Highs over the interior remaining in the 60s and lower 70s. Lows tonight with the high cloud cover in the 40s.

Classic marine push scenario Monday night with an upper level trough moving by to the north inducing an increase in low level onshore flow. Breezy conditions near the Strait of Juan de Fuca into Whidbey Island as well as along the coast into the Lower Chehalis Valley. Increasing clouds Monday night into Tuesday morning. Onshore gradients weakening Tuesday afternoon with sunshine returning to the area. Lows in the mid 30s to mid 40s. Highs Tuesday much cooler, in the lower to mid 50s. Felton

LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/

Extended models showing good run to run consistency through Friday. Upper level ridge well offshore combining with a stationary upper level low off Northern California giving Western Washington dry northwesterly flow aloft. Another round of frost advisories is possible for the Southwest Interior and Lower Chehalis Valley in the morning hours both Wednesday and Thursday. Lows in the 30s and lower 40s. Highs in the mid 50s to lower 60s.

Model consistency falls apart Saturday with the GFS bringing an upper level trough down from the north while the ECMWF cuts the trough off well north of the area. Ensembles not real excited about the trough scenario but enough solutions with light precipitation to include a chance of showers Saturday. Lows in the upper 30s to mid 40s. Highs remaining in the mid 50s to lower 60s.

AVIATION

High pressure aloft remains in place. Northerly surface winds continue over the area with speeds generally ranging 7-12 kts. This will persist into this evening before speeds ease below 7 kts. KOLM, KHQM, and to a lesser extent, KBLI are favored to see some fog and mist development this morning, lingering until 14-15Z before clearing out. Otherwise expect VFR conditions with just upper level cirrus clouds at times.

KSEA...VFR is expected through period under mostly clear skies. Northerly surface winds hold around 10 to 12 kt through this evening, easing by around 03Z tonight to 5-7 kts. Any low clouds that form in the vicinity this morning will remain away from the terminal area.

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MARINE

Broad high pressure remains in place across the area through Monday with a weak thermal trough build up along the west coast, keeping winds northerly. Winds will increase Monday evening as a front passes by to the north and stronger high pressure builds in behind it. Small Craft Advisory conditions look likely across much of the coastal waters, though will have to continue to monitor the potential for gales (30-50% probability) through the Strait of Juan de Fuca with a strong westerly push that moves into Admiralty Inlet and the Puget Sound. Winds will slowly ease on Tuesday and remain relatively light through the rest of the week as high pressure remains in place over the northeast Pacific.

Seas remain 3 to 6 ft through Monday. Seas will then build up to 8 to 11 ft Monday night into Tuesday, and these waves will be steep with dominant periods of around 8 to 9 seconds. The highest waves are also likely to be in the northern portions of the outer waters during this time. Seas look to remain in the 5 to 8 ft range through the rest of the week.

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HYDROLOGY

No river flooding the next 7 days.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...None.