Avalanche forecast

East Slopes South

Northwest Avalanche Center
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Avalanche danger

Thu
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Up to a foot of snow is forecasted to fall by the end of the day. Avalanche danger may start lower, but adjust your terrain selection as more snow falls. Avoid steep slopes, and if you see any recent avalanches or experience long, deep, shooting cracks or whumphing, steer around lower-angle terrain beneath steep slopes as well. 

Avalanche problems

  • Storm Slabs

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

    New snow, wind, and increasing daytime temperatures are a great recipe for avalanches. We're only forecasted to get a few inches of snow overnight before we get more during the day. Avalanche danger may start on moderate, but will increase to considerable as more snow falls. When the snow is falling at higher precipitation rates, you can expect to experience more avalanche activity.

    At first, shallow avalanches may be limited to wind slabs, but when the snow gets a little deeper, the distribution will likely expand to any deposits deeper than 6 inches, wind-drifted or not. A slight rise in temperature during the day will aid with an unstable new snow structure and may lead to more avalanche activity. Avoid slopes greater than 30°, especially as the day progresses and more snow falls. If you notice any natural avalanche activity or identify any other red flags, take another step back and avoid lower angle terrain beneath large, steep slopes.  

    Example photo: a slab avalanche that failed with a snowmobile trigger in a wind-loaded pocket in the East South zone. This type of area may be one of the places you can trigger avalanches on Wednesday. Note the cornice at the top of the slope- an obvious indicator wind is depositing snow beneath that feature. 

  • Deep Persistent Slabs

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

    A weak layer of facets exists 2-4 feet deep plus the new snow we're getting Tuesday. The depth of the layer is now pushing us into deep slab territory, where unsurvivable, very large avalanches may occur if you trigger an avalanche on this layer.  We haven't heard about avalanches  this layer nearby for the last several days, but on Sunday we received a couple observations of whumphing and concerning test results on persistent weak layers in both the neighboring EAST CENTRAL and WEST SOUTH zones. These reports were both very close to the boundary with the East South zone, where we have a similar structure.

    This problem is widespread throughout the zone, and in many parts of the region. Deep persistent slabs aren't something to take lightly, and they won't go away overnight. If you notice any red flags like whumphing and long shooting cracks, these are obvious indicators an avalanche could occur on a steep slope. Avoid open slopes greater than 30°, and take extra precautions by avoiding lower-angle terrain beneath steep slopes if you cause whumphing and long shooting cracks with your movement, as these are obvious indicators an avalanche could occur. 

Avalanche Discussion

The last few days wreaked havoc on the snow surface with the high pressure. Cold temperatures encouraged weak, faceted growth in lower density surface layers. Wind redistributed snow into drifts, forming thicker and harder deposits in other areas. It may be tough to identify what the old snow surface was like once more snow falls, so you may experience drastically different avalanche activity and bonding between the new and old snow layers, which might just be in a matter of feet. One slope may behave differently from the slope next to it. Even on the same slope, some pockets may behave differently from others. You can dig down to the new/old snow interface to identify bonding and use small test slopes, but they may not be representative a few feet away. 

If you get into the backcountry let us know what you found! Submit an observation HERE. 

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