Rain & Mountain Snow, Then Very Cold Weather Arrives

FastCast—Sunday, Feb. 20 to Thursday, Feb. 24:

A weather system moving through the region from the northwest will bring rain (rain shadow over the lowlands) and mountain snow. Convergence Zone bands will bring localized heavy rain and heavy mountain snow, especially around Snoqualmie and Stevens Passes. Expect an additional 5-15 inches of snow through Sunday at the passes. Heavy snowfall rates are possible in Convergence Zone bands. Breezy conditions are possible outside the Convergence Zone, with winds up to 35 mph. Shower activity will continue through Monday, with a chance of rain/snow mix or brief snow accumulations possible. Then, winds will shift to the N-NE and temperatures will drop. Expect lows in the 20s to low 30s from Tuesday to Friday mornings. The coldest mornings will likely be Wednesday and Thursday. Lows will reach the upper teens to low 20s. Wind chills will reach the low to mid teens at times next week. In Eastern WA and the Cascades, expect lows of -5 to 15 degrees, and wind chills of -20 to 15 degrees.

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The winds of change are blowing across Western Washington. A weather system is moving through from the northwest, shadowing the lowlands, but bringing snow to the mountains, likely totaling 1-2 feet by late Sunday. 

Below is the HRRR model forecast for snow through late Sunday.

Expect 1-2 feet of snow (more possible at higher elevations) through Sunday. Convergence Zone bands will bring locally heavier snowfall rates and briefly lower visibility. 

The northwest orientation of this system isn’t visible from the snow maps, but it is easy to see on the HRRR forecast for rainfall through Monday.

Light amounts of rain (0.1-0.3 inches) are expected in the lowlands, with more (0.4-1”) under the Convergence Zone, between north Seattle and Mount Vernon. 

Showers (potentially rain/snow mix or brief snow showers) will continue through Monday. Impacts or significant snow accumulations aren’t expected. Then, much colder air will move into Western Washington, as Arctic air moves south. 

Cold temperatures and wind chills are expected, coldest on Wednesday morning. Below is the European model forecast for Wednesday morning lows.

Expect very cold lows in the upper teens to low 20s on Wednesday morning, with lows in the 20s on Tuesday, Thursday, and possibly Friday mornings as well. The Cascades and Eastern Washington will have lows of -5 to 15 degrees.

Brisk northerly winds (especially in East-Central Washington) will bring very cold wind chills as well. Below are forecasted wind chills from the European model at 4 AM Wednesday, the coldest time.

Bitterly cold wind chills are expected at times next week, coldest on Tuesday and Wednesday. In Western Washington, expect wind chills of 5 to 20 degrees. In the Cascades and Eastern Washington, chills will reach -20 to 10 degrees. The Willamette Valley will also be very cold, at 5-10 degrees.

Stay tuned for more information about the very cold temperatures coming up!