Bulletin d’avalanche

Gunnison

Crested Butte Avalanche Center
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Danger d’avalanche

Wed
Alpin
1 · Faible
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 2 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Unusual weather can lead to unusual avalanche activity. Heightened avalanche conditions exist for the continuation of a wet avalanche cycle. Numerous wet loose avalanches ran yesterday. A couple of those were large in size, and in another example, old slabs were pried out when they were overrun by those loose wet avalanches. Monitor the amount of wet snow in the area you are traveling, and if you find a few inches of wet snow, consider moving to less consequential terrain or colder aspects. Old drifted slabs remain an isolated concern: choosing softer wind-eroded, or wind-sheltered snow can help keep you from lingering slab concerns.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    1–2

    Slabs up to several feet thick have become isolated and difficult to trigger, but remain a concern on a few previously wind-drifted slopes.  You are unlikely to see signs of instability before triggering an avalanche that breaks on old weak layers.  The most concerning terrain features are where old, drifted slabs are thin near their margins, convexities, or rocky areas. You can reliably avoid the problem on slope angles less than 30 degrees without steeper slopes above you, and wind-protected terrain generally lacks the problem.  

    This slab avalanche was observed yesterday on the northern side of Mt Wetstone. It's estimated to have been triggered by wet loose avalanche releasing from the easterly slope to the right. 

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    You can trigger wet avalanches as the upper snowpack moistens or gets wet.  Some of these may gouge deeper or grow larger than expected because of how weak and unconsolidated the existing snowpack is in wind-sheltered terrain - it's a wetter, heavier version of our facet sluff problem from the past few weeks.  Wet loose avalanches will be most dangerous in high-consequence terrain above cliffs, trees, or gullies. If snow surfaces produce rollerballs, pinwheels, or natural sluffs, move to less consequential terrain. You can avoid the problem on slope angles less than 35 degrees or colder aspects where the snow surface is frozen.  

    This wet loose avalanche ran naturally yesterday off the eastern side of Cascade Peak. 

Avalanche Discussion

Well, we are not setting record snowfall numbers, so apparently, Mother Nature thinks it's cool to set some record-high temperatures instead. The high-temperature yesterday hit into the 50s in Crested Butte, while the mountains saw high temperatures in the 40s. Last night, remote weather stations averaged low temperatures in the 30s. Several of those weather stations only saw below-freezing temperatures for 2 to 3 hours, while some, like the CBMR weather station at 11,300ft, saw a low temperature of 35 degrees. This spring weather is producing unusual avalanche conditions for February. High-thin clouds today may produce another greenhouse event that could moisten the snow surface on low-elevation northerly facing slopes and produce sluffs that are a hybrid wet/dry loose snow problem. 

This quick video captures a few highlights of some wet avalanches running yesterday. These things are cement mixers even when they are small and can easily push you into more hazardous terrain. If we had a strong spring snowpack, this wetting event wouldn't be notable. However, many terrain features have a weak and faceted snowpack, so when a wet avalanche gets moving, they are entrancing the dry faceted snow below and growing in size. You can use simple spring travel tactics to manage for wet avalanches: If you see rollerballs, pinwheels, or sink past your ankles through wet snow, be cautious in or below steeper terrain.

We're in an odd transition of a shallow and cold snowpack intersecting with the early arrival of spring weather.  In the springtime, we often head towards higher or colder aspects to avoid wet problems.  This strategy works today, but remember there is still isolated potential to encounter a hard slab in previously drifted terrain.  There were several human-triggered wind slabs and an explosive-triggered persistent slab last week.  Eric's observation from Cement Creek illustrates the types of slopes (smooth, rounded, drifted) where you might still find trouble. 

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