Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
View on map

Avalanche danger

Tue
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
Open full map
Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Monday is expected to be the warmest day of the past week. That’s saying a lot, considering how much rain and wet avalanche activity we have experienced lately. Give the snowpack time to adjust to this unseasonably warm weather by limiting the time you spend in avalanche terrain.

Avalanche problems

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    Free water exists in the snowpack around the Pass, maintaining the potential for various wet avalanches on Monday. These types of slides are poorly understood and often intermingled. Snow could shed from rocky ledges, cornices could sag and fail, and humans could push heavy snow on steep slopes. Any of these avalanches are dangerous in their own right. But the more significant concern is that they act as triggers for deeper and more dangerous slabs. We’re talking about low-likelihood, high-consequence slides, so limit the amount of time you spend in avalanche terrain.

    (1/28/2024)

    Wet avalanche debris, exposed rock ledges, and newly opened waterfalls and holes were observed in the Alpental Valley near Source Lake. 

    Photo: Jonathan Spitzer

Avalanche Discussion

Monday should bring a bit of a reprieve from the atmospheric river that has delivered roughly 3 inches of rain to Snoqualmie Pass since Friday. Although the rain is expected to stop, temperatures are expected to increase. Conditions will remain scary until the surface starts to freeze in a few days.

Observations during this period have been limited due to the storm's ferocity. Alpental Pro Patrol and a few backcountry travelers reported lots of wet avalanche activity and raging creeks. Waterfalls and creeks not often seen this time of year have been exposed. Some backcountry travelers observed a fully saturated snowpack to ground, while avalanche classes noted the wetting front extended only a foot below the surface to the 1/20 interface.  On Saturday, a freezing rain crust formed at middle elevations. It later started to break down in the warm rain but may not be entirely eliminated. 

This has been a unique period at Snoqualmie Pass. The layered and potentially weak snowpack structure ahead of the storm was tested by a week of slowly rising temperatures and precipitation leading up to Friday's start of the atmospheric river event. We are still gathering information on the extent of this weekend’s cycle at Snoqualmie Pass. It was very active in neighboring zones - including the West South, East Central, and Steven's Pass zones. As we look ahead to Monday, easterly winds may help to keep conditions in check, but we wouldn’t be surprised to hear of very large avalanches occurring. The freezing rain crust may have saved the snowpack from getting saturated in some areas. These slopes could be primed for a round of avalanches with the additional warmth. While the likelihood of triggering may lean toward Moderate danger, the travel advice and size of these potential avalanches align more with Considerable. 

Regions covered