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Out of date — this forecast expired 2 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Wet loose avalanches on Solar aspects will be possible to be triggered by riding or sliding on slopes steeper than 30 degrees as the Sun and temps heat the snowpack. Use caution on slopes getting heated by the Sun and move to a cooler aspect if you are seeing signs like natural avalanches or rollerballs.

Triggering deeper buried persistent weak layers is becoming less likely but it is still possible to trigger a 1-2' persistent slab on wind and sun-sheltered aspects.

Use good travel protocols on slopes steeper than 30 degrees like watching partners from a safe spot and only exposing one person at a time to slopes steeper than 30 degrees.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–1.5

    Above normal temps in the mountains and the valley will challenge snow on solar aspects to remain in place. As the day begins the Sun will heat up Eastern slopes first and then work its way around to Southern aspects, and finally, in the late afternoon/evening, Southwest and West aspects are going to be getting the hottest, shedding snow near rocky outcrops and on steep slopes facing directly into the Sun. 

    Most of the activity that will happen through the day naturally will be small, D-1 avalanches, but there is a chance that these small avalanches could grow larger or be just enough to overload deeper layers with the heavy wet snow.  

    If you are seeing natural avalanches or rollerballs on the surface or creating them yourself, it's a good time to find another aspect that is cooler and out of direct sunlight to play on.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Natural avalanches were observed throughout our advisory area this past week on Northern aspects that were sheltered from the Sun and wind in the upper 10-18 inches of the snowpack on a combination of buried surface hoar and graupel layers. Most avalanches were relatively harmless in the D-1 category, but some may have injured you (D1.5-2). Test pit scores recently indicate a lack of propagation potential in the majority of tests while others previously averaged hard.  

    Winds have done a good job of moving snow into leeward terrain mostly North and Eastern aspects when until recently the wind has been out of the North forming slabs in new places. Some of these slabs have possibly built upon persistent weak layers and may have a fairly weak bond that make it through stability tests for propagation (ECTN).  There remains a possibility to trigger one of these persistent slabs in Northern terrain, yet the chances are spotty as most natural activities indicated the avalanches are not running full track and are isolated pockets where the weak layer was likely better preserved.

    (3/13/2024)Public observation North of Tamarack Resort

    A skier triggered a D1 wind slab avalanche on north east aspect. Slab broke 4-10” deep, 30’ across and ran out less than 100ft down the slope.

Avalanche Discussion

The mountain snowpack right now is being challenged by abnormally warm temps. Cool Nothern winds have helped keep activity low and the warmup somewhat gradual. Large overhanging cornices were failing naturally Friday due to the intense Sun and heat. Weak layers in the snowpack that have been strong enough to hold together may not be able to handle the warmup and may become overwhelmed by the temps alone or fail when a cornice or a load of wet loose snow comes down onto a steep Southern slope.  Give room for error on these warm days and stay off of solar slopes that are getting overheated by the Sun. 

Northern aspects have some weak bonds due to layers of large graupel and surface hoar in the upper 2-3' of the snowpack that performs surprisingly well under stress from stability tests. The snow above weak layers has been dry and soft and lacks a lot of cohesion. Propagation on these weak layers has been reduced due to inconsistencies in the slab above them. As ambient temps warm up in the shade over the next couple of days we could see the snow above these weak layers gain hardness and enable energy to transfer, or a more of a slab to form above them and become a bit more sensitive.

Overall there is still some uncertainty as to how well our snowpack will be able to handle the stress of above-normal heat. With the uncertainty, stack the odds in your favor and put in place some room for error. Instead of party riding or skiing a steep slope, put only one person at a time on a steep slope so that if something does fail, you do not have your whole group involved. Watch your partners from a safe spot well out of the run-out of avalanche terrain, and carry your rescue gear on your back and not on your sled where it can become buried with the machine leaving you without the tools to help your buddy or yourself.

Today's advisory is sponsored by Skimo.

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