Our chase to Stevens was literally a 1-minute decision from Boulder on Monday, as the short-term models were offering good data on a convergence zone (west flow with cold air over the Puget Sound) for Tuesday night. Convergenze zones over the sound are not "lake effect" as you might see in Utah, but instead a cold pattern of circulating moisture that spins around the Olympic mountains and aims directly over Everett and pushes west (It is more of a directional result as opposed to lake effect). The secret to identifying them on models is a narrow band of moisture directly aimed at both I-90 and areas north of Stevens. You need westerly winds and cold air as clouds and moisture form. Models looked great.
This morning, Stevens had around 12 inches overnight, but that was on top of 12-15 from Monday. The quality was very good.
Below: Arrival at Stevens Pass on Tuesday morning. This car likley has the 2-day storm totals (Monday to Tuesday).
Discussion: In looking at multiple models, we like the odds of southern BC (Cypress) and, to a slightly lesser extent, of Whistler being decent by early Wednesday (7-10). Quality will be high with cold temps. In the PNW, snow starts a tad later, so early morning totals might range from 2 to 5 inches in the Cascades or less. The odds of good storm skiing exist in the Cascade range, with Baker, Stevens, and Crystal all in play. SW winds veering West will likley do well for Stevens later on Wednesday. Northern areas near Canada might be deeper initially. The storm peaks in moisture for the PNW on Wednesday night to Friday with strong winds, and a short-lived warm front followed by cooling. Winds will be extremely high in many areas of the PNW, Idaho, Montana, and perhaps southern BC (Shorter-lived duration).
Tuesday to Wednesday, midday.
Below: Snowfall from Tuesday evening to Wednsday morning. You can see highlighted areas in the BC mountains in both the coastal range, Vancouver (Cypress), and Whistler. Best estimates here are 6-12 inches with a bit more optimism in the N. Vancouver area.
Elsewhere, some bright pinks are noted in the southern Cascade range near Crystal, and pushing north to Stevens Pass. The heavy band of snow in BC seems to edge very close to Mt Baker. Baker might outperform Stevens by Wednesday morning with SW flow as opposed to the westerly flow in the past few days. Crystal might also bring a surprise!
Wednesday to Friday
Things get "Wild," with copious surges of moisture (3-6 additional inches of water), with widespread totals from Wednesday to Friday in the 3-6 feet range. The highest totals seem to be from the central Cascades (I-90 or Stevens) to Crystal, White Pass, and northern Oregon. Baker sees 1-2 feet, but keep reading as temps might stay colder there.
Wednesday to Thursday 2 AM - Cold to Warm-PNW/BC
Below: Warm front approaches the PNW on Wednesday, midday into early Thursday morning. This front edge is close to Whistler by late Wednesday night, and the southern interior BC mountains. Good news: On yesterday's models, the warm air stuck around for 24-48 hours, where current models show colder air moving back into the PNW by 2 AM on Thursday (Cooling). This warm spell will be brief!
Thursday morning PNW
Below: Cold air has returned to the PNW, BC (West and interior) by Thursday morning. The Idaho mountains to the east are still in the warm sector on Thursday for a short period
Thursday morning
The warm front is also impacting the panhandle of Idaho and most of northern Montana on Thursday morning (4700-foot snow level). YIKES. Notice that BC stays colder aside from the extreme south. This warm air will move out of all of these zones by Thursday midday and retreat to the Wyoming border.
The Bad- Winds from late Wednesday to Friday morning. Upper-level winds are extreme (Whites) with the strongest moisture fetch. It's really too bad, we have an AR with cold air with these strong winds. These winds approach BC later Wednesday to early Thursday, but seem to decrease midday Thursday. The northern Cascades (Baker) might also escape some of the highest gusts by Thursday midday. A narrow band of stronger winds seems to favor the southern Cascades, including Oregon, all the way into Friday.
Bottom Line: Unpredictable outcomes on quality, drifting, avalanche danger rising rapidly, lift holds, etc. You might be better off simply avoiding these zones until Later Friday or Saturday. Road closures are guaranteed in some areas (Trees will also be down on some approach roads). Deep snow of 5-7 foot totals are possible. 
Below: Those winds on Thursday stretch from the Pacific with a narrow peak line aimed at the southern or central Cascades, Northern Idaho, Montana, and southern BC. These winds will subside from north to south, with the southern Cascades possibly staying in the blow range longer.
Chases?
Perhaps it's Whistler, Cypress, coastal BC Tuesday night to early Wednesday (Colder and snowing heavily). Maybe Crystal, Baker, or Stevens by mid or later Wednesday (Crystal is warming earlier, so northern areas will likely be better and have better bases). Maybe consider interior BC for Wednesday night to Thursday (liking Kicking Horse, Revy, and perhaps the south as a wildcard). BC will be out of the wind funnel by Thursday.
Whitefish and the Ski Lookout get deep also by Thursday, but winds and temperatures are an issue initially.
Friday-Saturday- DEEP powder with wind decreasing (Can't guarantee quality) will allow ski areas to dig out in the PNW. Look for new openings at resorts. New openings at Crystal, which is suffering big time, might be widespread into Sunday/Monday. This is the storm that they needed!
OH- Wait- The Tetons grab a moderate storm with the leftovers on Saturday/Sunday.
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Forecaster: Powderchaser Steve @powderchasersteve (Insta)
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