Bollettino valanghe

Northwest Mountains

Crested Butte Avalanche Center
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Pericolo valanghe

Mon
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

Dry loose and wind slab avalanches will be your primary problems to manage today. Snow totals vary greatly across the NW Mountain forecast area, from a few inches to over a foot, with more in the forecast. Yesterday, observers noted many sluffs that were both running naturally or were human-triggered. A few wind slab avalanches were also reported. With lots of snow available for entrainment, even a small avalanche could become large as it runs through sustained steep terrain. Be aware that the cold temperatures may further rush your decision-making. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–2

    Previous northwesterly winds had redistributed much of the snow on Saturday, forming a few small wind slabs on lee terrain features. Now on Sunday wind speeds are generally light from the southwest. Alpine wind gusts will still be strong enough to transport some snow today and form small wind slabs in new areas. Where these slabs form over a previously weak snowpack, the resulting avalanches could propagate wider than expected, and further entrain available loose snow becoming larger in size. 

    This slab avalanche was human-triggered on Saturday, and though it didn't run far, it propagated widely on the old weak snowpack. 

  • Loose Dry

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    Accumulating snow is adding volume to the loose snow avalanche problem that we have been dealing with for the last week. In many areas, these sluffs are small and relatively easy to manage. In some areas, these sluffs can entrain enough volume to become large and difficult to manage. This avalanche problem will be the largest on northerly facing terrain, primarily below 11,500ft where the sluffs can entrain the entire weak snowpack. In extreme terrain, these sluffs may further run naturally. You can manage the problem by riding off the fall line or pulling out of the way to let your sluffs go past you. You can avoid the problem by riding on lower slope angles less than about 35 degrees. 

    Dry Loose avalanches start from a point, before growing in size. Don't be the tree and move to the side. In sustained steep terrain, this problem may grow large and difficult to manage. 

    Photo: Zach Guy

Avalanche Discussion

Dry loose avalanches and a few wind slabs, what is going on? These are some abnormal conditions for the Crested Butte area. Perhaps, not for the worse at the moment. New snow is accumulating and there is some excellent riding to be had. The lack of a notable persistent slab avalanche problem will have some people riding in steep terrain where they typically wouldn't be this time of year. If you are riding in proper avalanche terrain, don't be surprised if you encounter avalanche problems that may become more difficult to manage than expected. Sluffs are not an avalanche problem that we typically manage, because the typical persistent slab avalanche problem regularly keeps us out of that steep terrain this time of year. In some areas, those sluffs had already become notable and difficult to manage, before the accumulating new snow added additional volume to this avalanche problem.

We will eventually cross a line into a notable and widespread slab avalanche problem. New snow is accumulating onto a well-documented and very weak snowpack. The cold temperatures and relatively slowly accumulating snow is allowing us to stay on the better side of the line for now. The two main things that may first push us over that line would be high precipitation rates or elevated winds transporting snow. The current weather forecast is not calling for those high precipitation rates today, or sustained winds strong enough to transport snow. Those wind speeds will be something we need to keep a close eye on as we head into Monday and Tuesday and they will likely drive the avalanche danger ahead of the next storm on Wednesday. 

Storm totals since Friday vary widely, and with widely varying storm totals we can have a widely varying avalanche danger across the forecast area. In the northwest mountains as of 5am, those storm totals vary from a few inches to well over a foot in some areas. Schofield Pass and Irwin are measuring .3 to .4 SWE gains. In the SE Mountains, the new snow accumulations are meager as of 5am, with just a trace to a couple of inches. 

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