Avalanche forecast

Avalanche forecast

Payette Avalanche Center
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Avalanche danger

Alpine
1 · Low
Treeline
1 · Low
Below
1 · Low
Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Triggering a persistent slab avalanche has become unlikely, but not impossible. Isolated pockets of steep (greater than 35 degrees) north-facing terrain with shallow snow is where this problem could still be found. Watch for small wet loose slides on solar aspects as temperatures warm.

Avalanche problems

  • Persistent Slabs

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

    Triggering a slab avalanche on older, persistent weak layers has become unlikely. Poor structure still exists and the weak snow near the ground did not disappear. It would not be impossible to trigger an avalanche in steep (greater than 35 degrees) north-facing terrain. This problem is mostly confined to steep, rocky areas with shallow snow. You will not see any warning signs like cracking or collapsing. Your best way to manage this avalanche problem is to avoid the terrain where it is most likley hiding. The video to the right, highlights where you are most likely to find a persistent slab avalanche.

    ADDITIONAL DISCUSSION

    The last three days have been anomalously warm throughout the region. High temperatures have been poking into the 40s at upper elevations, with some areas seeing a very light overnight freeze. Expect to see the upper snow surface breaking down and becoming wet throughout the late morning and early afternoon hours, especially on solar aspects. On steep, south-facing slopes, a few inches of wet snow could slide easily on the 12/22 melt-freeze crust. Although very shallow, small wet loose slides could cause serious injury in consequential terrain.

Avalanche Discussion

The current weather pattern continues to deflect precipitation from our region. Along with that, we've seen a warming trend over the past several days particularly at elevation, where high and low temperatures are close to record highs. All of this is to say that the current snow surface is  mixed bag (melt-freeze crusts on solar aspects and near-surface facets in the shade). Although very small, the most likely encounter with an avalanche today would be wet loose snow sliding atop a melt-freeze crust buried 12/22 on solar aspects. With a poor overnight freeze, the upper snow surface on solar aspects could start breaking down and becoming moist by mid to late morning. The persistent weak layer (PWL) of facets from November has not gone away. If you dig into the snowpack above 7000' on a non-solar aspect, you'll likely find this PWL waiting to greet you near the ground. Even in areas where this problem is most pervasive (steep, rocky, north-facing slopes), test results prove stubborn. We have not seen or heard of any avalanches in several weeks. Unfortunately, it looks like we will be dealing with this weak snow near the ground for a while. Although this PWL is becoming mostly dormant, once we get more snow, this monster will wake back up. Even a small avalanche right now could have a negative outcome with the amount of obstacles that remain near and above the snow surface.

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