Avalanche forecast

Avalanche forecast

Payette Avalanche Center
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Avalanche danger

Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

The Avalanche Hazard throughout the West Central Mountains is Moderate today.  Wet loose avalanches will be the main concern as temperatures rise and another day of sunshine heats up the solar aspects.  Cornice failure will also be a factor to consider as temperatures rise, cornices make great bombs and may trigger deeper instabilities in the snowpack.  Wind slabs are stabilizing but may be resting on weak layers or crusts and could be triggered by the weight of a skier or snowmobile today in shaded, wind-loaded areas.  Shady aspects are preserving cold snow and the weak layers in them. 

Overall, the snowpack stability is increasing but warming temperatures add new problems to a cold snowpack.   Don't make assumptions about the stability of steep terrain right now, take the time to evaluate the snowpack if you are moving into steep, or shady terrain and avoid terrain that puts you under large cornices.  The combination of crusts on solar aspects and a growing layer of Near-Surface Facets and Surface Hoar on shady aspects will be our next weak layer.  With a new storm entering our area tomorrow afternoon, expect increasing hazard over the weekend.

 

 

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1

    Expect increasing wet loose avalanche activity again today as the temperature rises and intense sunshine warms the upper snowpack. Increasing winds will have a cooling effect on the snow and may reduce the warm-up slightly today.  Yesterday we could watch the wet loose slide activity increase throughout the day.  By 12 pm rollerballs were starting to do their thing near rocks and on slopes tipped towards the SE, by mid-afternoon, most sunny slopes were shedding snow.  Cornices are large and overhanging on most of our ridgelines, as they heat up, they lose the strength they had when temps were cold and begin to sag or break. We have seen several areas where large cornices have failed in the heat of the day this week.  Cornices are the bombs of the backcountry and may be just the right trigger for wind slabs perched below or deeper weak layers that are still present in the snowpack. 

    Wet loose avalanche activity on steep slopes seeing direct sun will be the name of the game again today. Cornices like the one in the foreground are starting to sag and fail in the heat of the day.

  • Wind Slabs

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

    Wind slabs are stabilizing as temperatures warm and the amount of soft snow for transport decreases.  In some areas, the wind slabs may be resting on weak layers or crusts that will make them more sensitive, so don't write them off as you are doing your mental slope stability checklist.  It is pretty apparent where recent winds have moved snow, you can see plenty of drifts and pillows on the leeward terrain.  Cornice failure is also likely to produce avalanche results in wind-loaded terrain.   As more cornices peel off the ridgelines today and tomorrow, we will certainly see them triggering wind slabs below them.  

     

     

    3/3/21 Cornice failure on a steep NE slope. This cornice triggered a slab below the rocks. Expect to see more of this in the next few days.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–3

    Our mid-February weak layers are still something to consider when you are choosing terrain.  Where the snowpack is deep and uniform, your chances of triggering an avalanche in these layers is relatively low.  Unfortunately, the snowpack is seldom uniform in the mountains. Variations in the depth of the snowpack to the weak layer make it a lot easier for us to initiate a failure in deeply buried weak layers.  Thin spots are common in rocky terrain and these slopes also tend to be the slopes we migrate to when the powder becomes harder to find.   Avalanche savvy folks across the Western U.S. are still giving steep terrain a lot of respect even with a low probability avalanche problem like this.  The consequences are pretty high.  If you are feeling lucky and looking at steep terrain, imagine what would happen if a large slab released; where would it take you, are there trees or cliffs in the runout, are there terrain traps like gullies or flats where debris is going to pile up quickly?  

     

     

     

     

     

     

     

     

    Sledders are moving into some fairly risky terrain. This is exactly the kind of slope where you could still release a deep persistent slab avalanche 3-4 feet thick.

Avalanche Discussion

PAC would like to encourage all users to take a pause, step back and look at the local statistics as well as the climbing number of fatalities this winter.  In our area, over the last couple of weeks, skiers and snowmobilers triggered, taken rides, got buried, got lucky, and reported natural and human-triggered avalanches occurring on many aspects.   Check your aspect and slope angle regularly... Across the U. S. we have had 33 avalanche fatalities so far this year.  

If you see or trigger avalanche activity, please take the time to snap a picture and note the approximate elevation and aspect, you can submit an observation on our website. Getting your info helps forecasters and other users get a better picture of the conditions throughout our mountains. If you have trouble using our observations page, please email us at: [email protected]

  Please be mindful of other users in the mountains, and where you are at. There are closures for motorized travel in and around the local ski areas, in the Lick Creek Canyon,  Granite Mtn, Jug Mountain, and other areas throughout our region.  Check out the Winter Travel Map to find out where you can shred on your sled or moto.  Not all of these areas are signed, it is your responsibility to know where these closures exist.