Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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In sintesi

As you ascend in elevation, look for wind-drifted piles of snow to steer around. Triggering even a small avalanche could be consequential near cliffs or terrain traps.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1

    As you ascend in elevation, you could run into some lingering Wind Slabs on Wednesday. You are more likely to encounter these slabs on leeward slopes below cornices or near rocky features such as cliffs and gullies. Several human-triggered Wind Slabs have been reported the past few days on similar features. You can look for textured snow surfaces or feel for wind-stiffened snow to help identify wind-loaded features you should avoid.

    (3/8/2021) This small Wind Slab was triggered by a skier on Monday on Wright Mountain. The slab broke near the base of cliffs and the cornice above serves as an indicator of the wind-loaded slope below. [Photo: Trevor Kostanich]

Avalanche Discussion

We have decided to remove the Deep Persistent Slab problem from our official problem list at Snoqualmie Pass. 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 at Snoqualmie Pass was over a week ago. (The Chair Peak slide on 2/28-3/1). The last suspected avalanche on this layer throughout the region may have been a few days later in the West South.
  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 8-10 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. 

As we inch closer toward springtime, a battle between sunshine and cool temperatures often plays out in the mountains, and this week is a good example. We don’t expect Wednesday to be a full sunshine day. However, if you find that the sun is out for a prolonged period of time, making the snow surface sticky and wet or producing rollerballs, Wet Loose avalanches may follow. This same phenomenon could also trigger the large cornices in our zone to start to fall, possibly triggering slides on the slopes below. If you notice the signs mentioned above, head for shaded slopes, keeping aware of terrain above you.

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.

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