Avalanche forecast

West Slopes South

Northwest Avalanche Center
View on map

Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
Open full map
Out of date — this forecast expired 5 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Saturday should be the warmest day this week, maintaining the possibility of the snowpack becoming weak and producing avalanches. Make sure you have travel plans that allow you to avoid steep sunny slopes if the snow surface starts getting sticky and wet.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Saturday will be day 3 of a warming trend and Wet Loose avalanches will be more likely as the day progresses on slopes that receive direct sunshine. Loose Wet avalanches typically start at a point, such as near trees and rocks, and are capable of entraining lots of snow, triggering slabs, and traveling far distances as they descend. If you notice signs of these avalanches such as rollerballs, snow shedding from trees and rocks, or new avalanches with fan-shaped debris, then seek out shaded terrain away from sun-exposed slopes above you.

    (3/11/2021) Rollerballs, pinwheels, and small Wet Loose avalanches were observed on Thursday (3/11) at Mount Rainier National Park as sunshine and rising freezing levels destabilized the snow surface.

Avalanche Discussion

Small Wet Loose avalanches and plenty of rollerballing have been observed the past few days as freezing levels have crept higher and sunny weather has impacted the West South. Expect a similar pattern on Saturday as freezing levels approach 8000’, the warmest of the period. These warm temperatures will help to minimize an overnight freeze on Friday night and could speed up the destabilization of the snow surface on Saturday. Warm-ups, like we are experiencing, are capable of weakening the snowpack and cornices, creating avalanches. The timing can be a little tricky to pin down, and many slopes that have not yet reached their tipping point could be primed for human triggers or the additional warming to put them over the edge on Saturday.  This includes cornices of all ages, so continue to give them a wide berth by not traveling on or below them.

At higher elevations on slopes that don’t see direct sunshine, there may still be cold dry snow that could be reactive on steep or rocky terrain. Before stepping into aggressive terrain, you should take a minute to look for wind-loaded features or a poor bond to the 3/5 crust.

We have decided to remove the Deep Persistent Slab problem from our official problem list in the West South. Although the weak snowpack structure remains, a few data points have made us feel more comfortable with this layer than we have recently.

  1. Our last confirmed natural avalanche on the Mid-January crust/facet layer in the West South was over a week ago. (Weekend of 2/27-2/28 near Crystal Mountain).
  2. We have a generally strong and well-settled upper snowpack above this layer. This includes the most recent 3/5 crust, which is thick and supportable in most locations throughout the zone.
  3. Since our last major loading event on this layer, test results have become more inconsistent than they were previously. 

The Mid-January crust still remains 6-10+ feet deep in the snowpack throughout much of the zone, and we believe it is currently dormant. It may wake back up at some point this season, however. At that point, we will put it back on the official problem list and continue to talk about the dangers this layer presents. Until that time, don’t forget about this layer. If you choose to enter more complex or large avalanche terrain, you should continue to talk with your partners about the low-likelihood/high consequence avalanches this layer is capable of producing. Keep in mind that when they occur, these avalanches have broken trees and descended far distances toward their maximum runouts in valley bottoms. The best way to mitigate your risk is to limit your time in and below large avalanche start zones, paths, and runouts. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

Regions covered