Lawinenlagebericht

Northwest Mountains

Crested Butte Avalanche Center
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Lawinengefahr

Thu
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

Wind-drifted slabs continue to slowly form at upper elevations on leeward features from west-southwest winds.  Additional snowfall this afternoon will provide more fuel for slab growth.  Snow texture in drifted areas will often look smooth and feel thick and more cohesive.  Look for scoured areas immediately adjacent to leeward features to help clue you in.  Cracking in the snow is a clear sign of unstable conditions. An AVALANCHE WATCH is in effect: large natural activity and very dangerous avalanche conditions are expected to develop by Thursday night.  

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    New snow accumulations were rather modest on Tuesday,  but westerly winds and additional snowfall on Wednesday afternoon will help form fresh slabs on leeward terrain features at upper elevations.  You are most likely to find newly formed slabs immediately below ridgetops, underneath cornices, and tucked behind rock outcrops/tree fences.  The most suspect slopes for Wind Slab formation previously possessed very weak and fragile snow surfaces which will help create slabs that are sensitive to the weight of a person.  Given the weak old snow surfaces on northerly-facing slopes, expect to be able to trigger avalanches that are thinner than you are accustomed to.  Avalanches are possible with as little as 6 inches of new or wind-blown snow.  

    An example of a Wind Slab avalanche tucked below an alpine peak immediately beneath a cornice.  This is a good example of the most suspect terrain today for triggering an avalanche. 

Avalanche Discussion

Tuesday night brought close to 5 inches of snow at treeline in the Northwest Mountains and the same areas could see close to an additional 5 inches this afternoon prior to sundown.  Westerly winds will be blowing just fast enough today to drift snow onto the same features that received wind-loading yesterday.  Wind Slab formation is expected to remain small in size but may be sensitive to the weight of a person.  Take a look at this observation from yesterday describing cracking snow and an intentionally-triggered avalanche below a cornice.  Distribution for the Wind Slab avalanche problem expanded into the near treeline elevation band in the Northwest Mountains to account for additional accumulations this afternoon.  The Southeast Mountains received less snowfall on Tuesday night and are forecasted to pick up only an inch or two this afternoon, so Wind Slab formation is likely relegated to above treeline terrain only.

A potent round of snowfall is expected to begin this afternoon and last through midday Friday.  Anticipate dangerous avalanche conditions to develop on Thursday and last into Friday which will likely include a natural avalanche cycle.  Stay tuned into the CBAC's weather and avalanche forecast to stay current with the rapidly changing conditions over the next two days. 

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