Avalanche forecast

Silver Valley & Bitterroot Mountains

Idaho Panhandle Avalanche Center
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Avalanche danger

Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Storm snow and moderate winds from the south have created soft slabs that will be easy to trigger in steep and open terrain at upper elevations. You can avoid triggering a soft slab avalanche today by avoiding steep and open terrain where the new snow has become affected by the winds. Watch for signs of cohesive and slabby snow in the surface of the snowpack. If you see shooting cracks in the snow, you will want to choose lower angle terrain that is sheltered by the timber.

Avalanche problems

  • Wind Slabs

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

    The Silver Valley Zone picked up 8-12" of fresh snow over the last 24 hours. Most of this snow fell light and cold and should create some fantastic riding conditions. In steep and open terrain, the new snow may be cohesive and slabby where it was compacted and transported by a southerly wind Friday. Steep and open terrain at upper elevations will be the locations to avoid today for the safest riding. If you see shooting cracks or other signs of instability, it is time to move to lower angle slopes that are sheltered by the timber.

    Loose-dry sloughing should also be on your radar today. Abundant amounts of light cold snow on the surface of the snowpack will slough easily in steep terrain. Though not as dangerous as a slab avalanche, it is enough to push you around right now, and is another good reason to avoid steep terrain today.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1.5–2.5

    A well-preserved layer of graupel sitting just above the February 19th ice lens is buried 1-2’ feet from surface on solar aspects, while a layer of buried surface hoar that developed on March 1st is buried anywhere from 10-16” around the compass rose. Although these layers have not shown a propensity to propagate in our recent stability tests, the buried surface hoar was the weak layer in last week’s slide on West Willow. The load from Friday’s storm will stress the weak layers in the upper snowpack, which may trigger a round of natural or human triggered avalanches today.

    Buried surface hoar from March 1st.

Avalanche Discussion

Thursday, Kyla, Katrina and Mikey enjoyed the mild temps and glimpses of sun poking through the clouds as we toured around Burke Summit. After a week of fairly innocuous weather, we found good stability and decided to descend via the Pipeline Couloir.

However, don’t count on Thursday’s snowpack evaluation to apply today. Friday’s snowstorm is changing the equation and the potential for avalanches has increased. 

We won’t know for sure how this will all play out until the storm subsides and we get a chance to investigate the snowpack, but we do know that avalanche hazards increase with rapid loading. The big questions that influence the avalanche danger today and tomorrow are: How is the new snow bonding to the old snow surface? What effect does the new snow load have on the weak layers in the upper snowpack? Wind speed and direction are also a big factor in the equation right now.

Add a margin of safety into your plan if you head out today. Be leery of steep and open terrain this afternoon. Tree skiing/riding and lower angle slopes will be the safe bet after Friday's storm.

Thank you to the folks who have submitted observations in the past week. Our forecasts are better when we have data points from across the zone that help paint a more complete picture of the snowpack. Information that is helpful in an observation include: recent avalanches, signs of instability, snowpack test results, weather observations, height of snow, depth of persistent layers, elevation and aspect, and overall impression of stability. Feel free to submit anonymously and don’t feel obliged to pin-point your honey hole on the map. Thanks for supporting the backcountry snow going community with your observations.

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