Bollettino valanghe

Northwest Mountains

Crested Butte Avalanche Center
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Pericolo valanghe

Tue
Alta quota
1 · Debole
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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In sintesi

You may encounter isolated slab avalanche concerns.  Strong northerly winds on Sunday may have formed thin, hard drifts on leeward terrain features.  Identify these smooth, small drifts and steer around them.  On the northern half of the compass, triggering an avalanche on weak layers deeper in the snowpack is unlikely, but not impossible.  Avoid areas where you might find a trigger point, such as rocky areas, convex rolls, or slopes with shallower-than-average coverage.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    2–2.5

    Old, hard slabs 2–3+ feet thick linger over buried weak layers but are becoming increasingly hard to trigger and less common. Without obvious warning signs, avalanches are most likely triggered where the slab is thinner and easier to impact the weak layer below.  One way to reduce the risk of triggering is to avoid steep terrain with a thin or variable snowpack, such as rocky areas, rollovers, or places where wind has created uneven slab thickness. Southerly aspects and slopes with consistently deep and uniform snow depths offer safer options from this problem.  

    This was the last Persistent Slab avalanche observed in the NW Mountain forecast area. It released ( 2/28) below a cornice on a steep face that has avalanched multiple times this winter. 

Avalanche Discussion

Persistent slab issues linger on northerly slopes, typically near and above treeline.  In the Northwest Mountains, the chances of triggering a slab that breaks on weak layers several feet deep have slowly become unlikely.  As you transition from the deeper snowpack to the west and northwest of Crested Butte into the shallower regions near town and to the east, the Persistent Slab problem becomes more probable.  Slabs become thinner, and weak layers are better developed.  Two recent natural avalanches provide supporting evidence to this idea.  Earlier this week, during a period of light wind loading, this avalanche failed on Mount Whetstone.  Another avalanche failed this weekend in the Aspen area, likely during Saturday night's wind event.  Both avalanches exemplify terrain with highly variable slab thickness due to wind effects.  Steer clear of this type of terrain in both forecast zones to reduce your chances of an avalanche.

An extreme wind event on Saturday night and Sunday blasted the landscape and transported snow.  In most cases, the snow disappeared into the atmosphere or ended up at the bottom of basins.  There could be a few isolated places where the wind formed shallow slabs in unusual places.  Identify places with smooth, hard textures and simply steer around them to avoid the potential trouble.

Cooler temperatures and gusty northerly winds keep most sunny surfaces frozen on Monday.  Wet avalanche concerns may be absent for another day or two before returning with vengeance later this week.  Temperatures soar 20-ish degrees above normal by the end of the week.  Expect loose avalanche activity to grow large and gouge into the snowpack.  Wet slab concerns develop later this week.

Regioni coperte