Winter Storm Watch issued for parts of region for midweek storm

Story Published: Feb 21, 2011 at 3:38 PM PST

Story Updated: Feb 21, 2011 at 11:35 PM PST

Winter Storm Watch issued for parts of region for midweek storm SEATTLE – And you thought La Nina had forgotten about us…

Winter’s 6-week hiatus is about to come to an end as a cold and potentially snowy weather pattern readies to set up shop in Western Washington, with areas in Northwestern Washington potentially dealing with a combination of heavy snow and blistering wind later in the week.

A Winter Storm Watch is now in effect from Wednesday morning through Thursday morning for parts of the region, including the area from Snohomish County north to the Canadian Border and the Eastside foothills of King County. there is potential for 4-6 inches of snow in the watch areas. the Seattle and Tacoma Metro areas are not in the watch, but could still see lighter amounts of snow.

Snow chances begin as early as Monday night, but low elevation areas don’t really have potential to see any accumulations until at least Tuesday or Wednesday.

In the short term, the set up will be similar to last week when we saw hit-and-miss snow or rain/snow mix showers that had little to no accumulations. a cool air mass remains in place and a weak system will move in late Monday evening.

Warmer southerly breezes have kept temperatures well above freezing during the day, but heavier showers could briefly cool the air to the mid 30s and drag the snow levels to a few hundred feet or lower, making for a passing snow shower.

That’s already been the case Monday evening, as an expected Puget Sound Convergence Zone formed and will continue to bring rain or wet snow to its usual spots in northern King and/or southern Snohomish County. These zones can create intense precipitation that again drags snow levels down to the surface.

Thus the areas in southern Snohomish and northern King County need to be on alert for a little snow to fall Monday night and Tuesday. Conditions are still marginal for snow but this area could see a slushy 1″, especially above 500 feet which includes the Lynnwood/Alderwood, Mukilteo, and Mill Creek areas where you’re up around those elevations. farther east toward the foothills, you have a better chance of seeing 1-2″ of accumulations.

Elsewhere, we are still looking at the same pattern as last week: Random showers that could temporarily be in the form of snow that leave little to no accumulations, again best chance above 500 feet so the higher King and Pierce County foothills could also see some minor snow accumulations. but overall, I think Seattle-Bellevue-Tacoma proper areas should be fine for the Tuesday commute, but as we said, the Everett area might have a little snow to deal with.

These random rain/snow showers will continue into Tuesday night with snow levels dropping a little lower (to a few hundred feet) meaning even some of the higher Seattle hilltops could see some minor accumulations in a passing snow shower and could see non-sticking snow down to sea-level.

Wednesday into Wednesday Night/Thursday Morning

More moisture will move in from the northwest on Wednesday, and in addition it looks like we’ll get a stronger shot of arctic air from the Fraser River Valley by afternoon, giving more favorable conditions for snow to the surface across the entire region, especially as we get into late Wednesday and Wednesday night.

Snow should begin in Whatcom County during the late morning hours, and spread south and east through the day. Forecast model guidance continues to show a potential for heavy snow showers from Snohomish County north to the Canadian border and across the northern Olympic Peninsula with a bulls-eye around Skagit and Island Counties, where as much as 4-6 inches of snow could fall during this period, prompting the Winter Storm Watch.

All other areas, including Seattle, Tacoma, Bremerton, and Olympia, are also expected to get some accumulating snow of a few inches late Wednesday through Thursday morning, but at this point forecasted totals are not high enough to warrant a winter storm watch, although the National Weather Service hinted that the watch could later be expanded south to include Seattle and Tacoma (part of their challenge is that watches aren’t supposed to be issued more than 48 hours in advance of event and the snow would be later in Seattle/Tacoma as it’d take longer for the snow to move south.)

We’ll also have to watch for dropping temperatures during and behind the snow as arctic air follows in behind the snow, giving potential for icy roads in the snow’s wake Wednesday night into early Thursday.

There is also potential for strong northeast winds coming out of the Fraser River Valley, affecting Whatcom and San Juan Counties on Wednesday into Thursday. Wind gusts could reach 40-55 mph, causing blowing snow in the area. IN addition, this could also bring freezing spray to the San Juan Islands as that roaring wind blows sea water ashore.

Bottom line, as of now, Wednesday midday through Thursday morning is our best chance of lowland snow of the week, with greatest chances for getting snow and accumulations north of Seattle, so factor that into any plans.

Thursday midday through the weekend

Models indicate we dry out as more arctic air pools into the region, and return to a cold and sunny pattern for the end of the week. Highs on Thursday, Friday and Saturday will only be in the 30s with hard freezes overnight. Lows in Seattle will drop to the low-mid 20s with teens likely in the outlying areas.

Heavy snow in mountains too

Almost forgot: a Winter Storm Warning is in effect for the Cascades, which just figure are going to get gobs upon gobs of snow tonight through Thursday. Forecasted snow totals are for 18-24″ by Wednesday morning but there is plenty more behind it through Thursday.

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KOMO News: Twitter @komonews / FacebookSteve Pool: Twitter @StevePoolKOMO / FacebookPaul Deanno: Twitter @PaulDeannoKOMO / FacebookScott Sistek: Twitter @ScottSKOMO / Facebook

Winter Storm Watch issued for parts of region for midweek storm

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