Mountain Snow, Winds, Rain, and Dangerous Cold Ahead

No FastCast today, keep reading below for a summary of the active weather ahead for the Pacific Northwest.

A lot of active weather is ahead for the Northwest, with heavy mountain snow, strong winds, rain, and very cold temperatures ahead. Let's take a look at the forecasts.

Quick note: Avalanche Warning in effect for Snoqualmie and Stevens Passes through Monday evening. Check avalanche forecasts at the Northwest Avalanche Center (NWAC).

Below is the European model forecast for snow through Wednesday evening.

The European model shows 12-18 inches at Snoqualmie Pass and 24-36 inches at Stevens Pass through midweek. Most of Eastern Washington (outside lower elevations of the Basin) will get 1-3 inches, except 5-8 inches near Wenatchee. 

Let's compare this to the UW WRF model, also showing snow through Wednesday morning (shorter than the European model).

The UW forecast shows 12-18 inches at Snoqualmie Pass and 24-36 inches at Stevens Pass, similar to the European model.

In short, be prepared for significant winter storm conditions crossing the passes from Monday through Tuesday, with challenging conditions still possible on Wednesday. Be prepared for delays and closures if crossing the state. Note: Snoqualmie Pass will remain mostly rain on Monday, before transitioning to snow late Monday night.

With a strong system moving into the region from Monday through Tuesday, there will be a large area of onshore flow, bringing gusty winds for most of the state.

Below is the European model, showing peak gusts early Tuesday morning, likely peak winds for Western Washington.

Generally, expect gusts 35-45 mph for Western Washington, except 50-65 mph westerly gusts along the Strait, Whidbey Island, and Admiralty Inlet. Eastern Washington and the Cascades will experience gusts of 50-60 mph, peaking early Tuesday morning. Some blowing snow is possible for the Cascades.

Let's take a look at the total rain expected for Western Washington through Wednesday morning.

Generally, expect 0.3-0.9 inches from Tacoma northward, with 0.2-0.4 inches from Tacoma south. On the coast and from Everett northward, expect 1-1.5 inches. 

Finally, a look at the upcoming cold temperatures. The coldest temperatures don’t arrive until late Wednesday night, likely continuing through Friday morning. Coldest temperatures will be in the mornings.

Below is the European model forecast for lows on Thursday morning.

In Western Washington, expect lows in the mid 20s, except the low 20s in Whatcom County, the Willamette Valley, and the Cascade foothills. In Eastern Washington and the Cascades, expect frigid lows from zero to the low teens, with some isolated readings below zero.

Another big issue with the cold temperatures will be the frigid wind chills due to brisk northerly outflow winds. Below is the European model forecast for wind chills around 7 AM Thursday.

Dangerous wind chills are possible, likely dropping to the upper single digits to mid teens for Western Washington and from zero to -20 for Eastern Washington.

Details on the frigid temperatures and dangerous wind chills are still evolving, so stay tuned. I’ll have another blog Monday night with updates on the mountain snow, winds, and potential (slight chance) lowland snow.