Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
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Avalanche danger

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

Over the last 24 hours, the NW Mountains have received an average of 6 to 9 inches of new snow. After a lull in wind speeds last night, we'll see winds increasing again today and keep wind slabs as your primary avalanche problem. Hiding from the wind today, and over the next couple of days, will help you avoid this avalanche problem and potentially find some of the better riding conditions. In wind-sheltered terrain, keep your eye out for isolated areas potentially holding shallow soft slabs in the new snow, or the potential to manage loose snow avalanches in steep terrain. 

Avalanche problems

  • Wind Slabs

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

    New snow combined with strong southwest to west winds has created potentially sensitive wind slabs. In many areas, these slabs will be small in size, but in snow favored areas of the Ruby Range and the northern Elk Mountains, these slabs could become 14 to 20 inches thick and large in size. This avalanche problem will be the most widespread on the lee sides of ridgelines and cross-loaded terrain features at near and above treeline elevations. This avalanche problem will be less common at below treeline elevations and exist on a few cross-loaded terrain features. A wind slab is classically represented by a rounded or lens-shaped snow deposit, where additional snow has accumulated on the lee side of the terrain feature. 

    An example of a shallow wind slab from earlear this winter. 

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1.5–2

     Slab avalanches breaking into old weak layers several feet deep have become unlikely, but not impossible.  Higher elevation, northerly facing terrain still holds a dry, winterlike snowpack; thus we can't completely eliminate the potential for a rare but large slab avalanche on these aspects.  The most suspect terrain is where snow coverage is shallower,  especially on convex, unsupported slopes or near rock bands. You are most likely to trigger a slide from a shallower spot on the slope.  If you are skiing or riding in that type of terrain, reduce your group's exposure during uphill travel and choose appropriate safe zones from a large avalanche while descending.  Let your friend wrestle their stuck snowmobile off of suspect slopes by themselves.  

    Example of our most recent persistent slab avalanche that likely failed around March 30th.  This large avalanche highlights the type of terrain that remains most worrisome:  northerly, rocky, and unsupported.  

Avalanche Discussion

The wind and new snow that is available for transport are combining to drive the avalanche danger right now. The wind station at 11,300ft on CBMR recorded several hours yesterday of SW winds averaging in the 20mph range with gusts into the 30's. Alpine winds were obviously much stronger. After a lull in wind speeds last night, we'll see a return to windy conditions today and over the next several days. The avalanche conditions are somewhat simple right now. With new snow and wind, we land at wind slab avalanches and the most dangerous areas being wind-loaded terrain. We didn't have enough snow accumulate yesterday to create a wider storm slab avalanche problem in wind sheltered terrain. The snowpack below this recent snow has become well settled and generally stable thanks to several periods with above freezing temperatures in the last weeks. The persistent slab avalanche problem has been unlikely for some time now, with little change to note. 

Wind-loaded terrain at near and above treeline elevations is fairly obvious. If someone were to get caught off guard by an avalanche today, I'd expect it to be at a lower elevation, where just a subtle amount of wind has created an isolated slab where the rider didn't expect it. If you avoid wind-loaded slopes, then it's a great time to ride steep terrain. Just stay heads up for those areas where a small slab or a loose snow avalanche could catch you off guard. 

The avalanche danger across our two forecasts is highest in the areas that have received the most recent snow, and lower in the areas that have received less recent snow. The wind will keep driving any new snow available for transport onto wind-loaded slopes over the coming days. If we don't see much snow accumulate today, then the avalanche danger will continue to slowly decrease as there becomes less snow available for transport. However if the unsettled weather delivers more snow than expected over the next 24 hours, you should first do a little party dance, then expect the avalanche danger to remain steady. 

Regions covered