SnowBrains Forecast: Extended Period of Snowy Weather For the PNW, 4+ Feet Expected

After a quiet start with persistent high pressure, things get progressively more interesting as we move deeper into the week. Wednesday night into Thursday marks the start of a more active pattern, with multiple waves of moisture rolling into the Pacific Northwest. Each successive disturbance will tap into increasingly robust moisture, meaning a consistent stream of snowfall for the high terrain. The Cascades, from Washington down into northern Oregon, will see several rounds of accumulating snow through much of the next week. The biggest action appears to ramp up significantly by the weekend and into early next week, when a stronger system should bring more widespread and heavier snowfall totals.

The early to midweek period remains relatively subdued, with a stable ridge overhead through Wednesday keeping conditions generally dry and cool. However, by late Wednesday night into Thursday (December 11-12), the pattern begins to break down as the first in a series of weak disturbances spreads light precipitation across the Cascades. Initially, amounts will be modest, but it sets the stage for what’s to come.

From Thursday onward, a steady barrage of disturbances brings snow to the Washington and Oregon Cascades. The first few waves, Thursday into Friday (December 12-13), look somewhat disorganized, and snowfall may be hit-or-miss at times. Still, these early storms lay down a fresh coating at the resorts, keeping surfaces soft, especially at mid and upper elevations. Temperatures remain cool enough that all of this precipitation will fall as snow at resorts. Expect a nice refresh heading into the weekend.

Confidence is growing that the weekend (Saturday December 14 into Sunday December 15) will bring a more potent storm to the region. This system appears to carry deeper moisture and more sustained precipitation rates. The Cascades, from the North Cascades of Washington down to the central Oregon high peaks, are positioned favorably to pick up significant snowfall accumulations. Multi-day snowfall totals from Thursday through mid-next week look impressive at nearly all major resorts, likely setting up a prolonged period of excellent conditions. The farther out we go—especially into early next week (December 16-18)—the more uncertainty creeps in. Models still agree on continued unsettled weather, so it’s safe to say the storm window remains open. Just remember these forecasts are bound to evolve, and numbers may shift around as we get closer to those dates.

Below are the total forecast snowfall ranges from Wednesday night (December 11) through Wednesday night (December 18). Some of the largest totals occur later in the forecast window, so there is still a lot of uncertainty, and these estimates may change. Stay tuned for updates.

• Timberline: 30-51 inches (majority falling Thursday night through early next week)
• Mt Baker: 28-46 inches (steady snowfall from Thursday through the following Wednesday)
• Stevens Pass: 23-38 inches (accumulations ramping up over the weekend and into next week)
• Crystal Mountain: 21-36 inches (picking up scattered snowfall late this week and building over the weekend)
• Mt Bachelor: 21-35 inches (initial push Wednesday night into Thursday, with more on the way through the weekend and beyond)
• Snoqualmie Pass: 20-33 inches (gradual accumulations starting Thursday, with heavier totals possible over the weekend)

Long-Range Outlook: Beyond mid-next week, the door stays wide open for additional storms coming off the Pacific, keeping the forecast wet and snowy. Models continue to hint at more storm energy driving into the region late next week, which would reinforce the active pattern. At this point, it’s almost certain that the Pacific Northwest mountains will remain well supplied with fresh snowfall. Keep checking back as we’ll refine these numbers and details as the storm cycle unfolds.