textproduct: Seattle/Tacoma

SYNOPSIS

Zonal flow aloft is contributing to calmer conditions through this weekend. Another system will arrive on Tuesday for more rain and breezy winds. Another weak front will arrive on Thursday. For the late week period into early next week, high pressure looks favored with thermally induced troughing along the Oregon coast.

SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/

This afternoon's satellite imagery shows mostly clear conditions across western Washington with only mid and upper level clouds streaming through. Highs in the low 60s for both today and tomorrow. Given the clear skies and light surface winds, some patchy fog development is possible overnight into Sunday morning. Whatever develops will generally dissipate by midmorning. Sunday morning lows will be in the low 40s to upper 30s in the Cascades and adjacent foothills. Despite the zonal flow, drier afternoon relative humidity is in the forecast for tomorrow primarily in the mountains. Afternoon RH minimums in the upper 30 percent range is likely.

Monday now looks generally clear and a couple degrees cooler, with the next system arriving Monday night into Tuesday from the northwest.

LONG TERM /TUESDAY THROUGH SATURDAY/

Into Tuesday, areas favored for more precipitation will be the North Cascades, Olympics and areas from King County north. Breezy winds are forecast for the coast and northern inland waters. The rain will taper off late Tuesday, for a drier Wednesday and Thursday. A decaying frontal system may increase some clouds over the area on Thursday, with little in the way of meaningful precipitation for that time frame.

High pressure seems favored to return late in the week and over next weekend. The high will cause thermally induced troughing over the OR/WA border and increase the high temperatures back into the upper 60s and possibly low 70s.

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AVIATION

Weak high pressure and offshore flow will lead to dry and stable conditions across western WA tonight. Pockets of low clouds and fog are likely around the south sound overnight. Any fog and/or low clouds will be shallow and dissipate by 18z Sun. Otherwise, expect VFR conditions on Sunday with mainly high clouds aloft. 33

KSEA...VFR conditions expected tonight into Sunday with a N wind around 10 kt. 33

MARINE

Weak high pressure and offshore flow tonight. A weak front will dissipate over the offshore waters on Sunday. Southerly flow will increase Monday night and Tuesday with a stronger frontal system. Weak high pressure and offshore flow will follow on Wednesday. 33

SEW WATCHES/WARNINGS/ADVISORIES

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