Lawinenlagebericht

West Slopes South

Northwest Avalanche Center
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Lawinengefahr

Thu
Hochgebirge
2 · Mässig
Waldgrenze
1 · Gering
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 5 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Piles of wind-drifted snow could be present on a variety of terrain features as you ascend in elevation on Wednesday. Steer around these piles where you are more likely to trigger an avalanche. If the snow surface is changing throughout the day due to the sun’s input, be prepared to alter your travel plans.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1

    You could run into some lingering Wind Slabs around the West South on Wednesday. You are more likely to encounter these slabs as you ascend in elevation near rocky features such as cliffs and gullies. Shifting wind directions the past few days may have created slabs on a variety of aspects as well as some mid-slope or cross-loaded features. You can look for textured snow surfaces or feel for wind-stiffened snow to help identify wind-loaded features you should avoid. If you notice fresh or very large cornices, avoid traveling on the slopes beneath them and give them plenty of space on ridgelines.

    (3/7/2021) We intentionally triggered this small wind slab on a test slope near treeline. Small features like this can help highlight conditions on larger slopes. NW, 6100'. SS-ASc-D1-R2-S

Avalanche Discussion

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. 

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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