Avalanche forecast

Avalanche forecast

Payette Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

Slopes steeper than 30 degrees should be approached with caution. Evaluate the snowpack before committing to steep, exposed, or complex terrain.

Winds have formed slabs on all aspects, and most recent North winds have likely created sensitive slabs that may fail 6"-1' under the weight of a rider or skier. Buried weak layers on all aspects have formed a persistent slab up to 2 feet thick that is showing some signs of strengthening.

 If you are seeing red flags like cracking or whumphing sounds in the snowpack, find another safer route that is lower in slope angle.

Avalanche problems

  • Wind Slabs

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

    North winds picked up yesterday and gusted last night into the upper teens and twenties in some locations.  Fresh slabs 6 inches to a foot deep are possible in mid and upper-elevation exposed and leeward terrain. Previous winds during the storm on Saturday gusted into the thirties out of the South. 

    Pay attention to signs of wind slabs on all aspects, especially near ridgelines and cornices.  If you are seeing red flags like cracking or womphing sounds in the snowpack, find another safer route that is lower in slope angle.

    (4/3/2023)

    Lone Tree's North Face showing signs of wind slab.

    Photo: GH

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2.5

    Our snowpack is holding a combination of crusts and facets that formed from melting and freezing during warm and or sunny conditions. Bonding between these crust combos that formed March 20 & 23 has been minimal to none and has shown failures from isolation to compression, propagating in extended column tests last Friday, and showing red flags like cracking and whumphing on Saturday reported by a couple of users.

    Saturday's storm load caused natural avalanches on northern aspects and Southern aspects went Naturally on Monday afternoon during a brief warmup. The snowpack is slowly strengthening yet is going to take some more time to transition to springlike. We have not only crust facet combos on solar aspects but have observed some pieces of buried surface hoar that likely contributed to Saturday's natural cycle. The upper 2 feet of the snowpack is loose, especially on shaded aspects...Use caution on all aspects, on slopes 30-40 degrees in slope angle, and especially mid-elevation slopes that may have more preserved buried weak layers. 

    (4/3/2023)

    This Natural avalanche was observed on Monday from Lone Tree that released towards the end of the Storm Saturday-Sunday.

    Photo: GH

Avalanche Discussion

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Our snowpack is still holding some winter-like characteristics like weak layers of crust facet combos on solar aspects that are not bonded well if at all. Our Northern aspects have shown some buried weak layers of surface hoar fragments and near surface facets. We had test results showing propagation last week, and thus have had some reports during Saturday's storm of whumphing and cracking in the snowpack as well as natural avalanches observed from slabs failing during the storm.

While the signs are pointing toward strengthening, there are some layers that are poor for a good structure of a snowpack, and we have a lot of loose snow in the upper 1-2 feet of the snowpack. Warming temps through the week will aid in weak layers failing under the weight of a rider or skier or under heat and solar gain. Use your best travel protocols and extra caution on all slopes steep enough to slide, and evaluate the snowpack before committing to big consequential or complex terrain. Within our advisory area, our stability seems to be much better that the reports to our South near Warm Lake where a much weaker snowpack was reported.