Updated Friday 5:35 p.m.
A very busy night around here -- let's start with the snow. We're still rain at times this evening with some mixed snow in Snohomish County, but temperatures will cool later tonight and snow levels will drop. A Snow Advisory is in effect from 9 p.m. Friday through 11 a.m. Saturday for as much as 1-3 inches of snow for King, Snohomish, Island and Skagit Counties plus eastern Clallam County and eastern Kitsap County, with particular emphasis on Snohomish County. Temperatures in the 50s in the morning have plummeted to the 40s and 30s with parts of Snohomish County already had some rain/snow or wet snow Friday afternoon with temperatures in the mid-upper 30s.
A secondary arctic front is expected to slide south out of British Columbia late Friday evening, bringing snow levels to the surface region-wide and bringing a little snow (Trace-1") to the far northern areas of Washington before settling in and potentially stalling over Snohomish County for a few hours in the overnight hours as a convergence zone, bringing a few inches of snow there, especially spots away from the Sound and with elevation such as Lynnwood, Mukilteo, Mountlake Terrace, South Everett, Mill Creek and Bothell. And we could see a little more - perhaps as much as 4 inches in spots in the eastern Snohomish County foothills. Areas a few miles north and south of southwestern Snohomish County will likely get a little less -- spots like North Seattle and Arlington/Mt. Vernon as well as spots in Kitsap County like Poulsbo and Kingston.
While that is the most likely areas of snow, there is enough geographic uncertainty in convergence zones that snow could spread as far south as Seattle and south King County, and as far north as northern Skagit County so the advisory covers those areas, so those living there should be aware of potential for a few inches of snow, but your chances are less than the Snohomish County area.
So to recap: southern Snohomish County best spot for snow late Friday evening and overnight with 1-3" possible, maybe spots of 4" east; areas a county north and south of there less certain with lower totals expected.
We also have another band of snow expected along the northeastern Olympic Peninsula from Port Angeles east through Sequim to Discovery Bay -- this is due to cold air coming out of the Fraser Valley via a strong northeast winds that will flow up the Olympic Mountains and bring snow along 101 (sort of like a reverse rain shadow). As much as 1-3" are possible there, most away from the Strait.
All other areas - like the coast; South Sound, and Southwestern Washington, are not expecting any accumulating snow to due to lack of moisture. Just mostly cloudy skies with a few flurries and lows in the low 30s.
Snow tapers off Saturday morning and we clear out and remain cold with highs only in the mid 30s. The cold air will be accompanied by strong northeasterly winds coming out from the Fraser River Valley. A Wind Advisory is in effect for Whatcom County and the San Juan Islands for northeast winds up to 50 mph late Friday through 3 p.m. Saturday.
With clear skies Saturday night, temperatures will plummet into the mid teens to low 20s Saturday night for a very hard freeze and very slick roads again for Sunday morning.
Sunny but very cold for Sunday with highs only in the mid 30s. Those going to the marathon and the Sounders game need to really bundle up.
A hard freeze again Sunday night and then a slow moderation trend for next week, with partly sunny skies early next week with highs in the low 40s and lows in the mid 30s.
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