Bulletin d’avalanche

Southeast Mountains

Crested Butte Avalanche Center
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Danger d’avalanche

Mon
Alpin
2 · Modéré
Limite forestière
1 · Faible
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 3 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Santa teased us yesterday with a skunk and then delivered that skunk this morning. Storm totals in the SE Mountains average in the 2" to 3" range. That new snow combined with northwest winds to create small wind slabs at upper elevations. The larger persistent slab avalanche problem remains isolated in the big picture scale, with a low likelihood of triggering. Enjoy the little bit of new snow, the riding conditions may be better than you expected. If you find yourself uncertain about the avalanche problems, defer to simpler and low-consequence terrain. 

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–1.5

    Since Friday evening, 2" to 4" of snow has accumulated. Upper-elevation winds have been just strong enough to transport that new snow into small wind slab. Wind slabs can form on the lee sides of ridgelines and cross-loaded terrain features. There is a remote possibility that an avalanche triggered in the new snow could further step down into the persistent slab avalanche problem nd become larger than expected. 

    A small soft slab that was triggered in the NW Mountains on Saturday 12/23. 

  • Persistent Slabs

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

    Slabs 1 to 3 feet thick exist over several persistent weak layers in the snowpack:  Weak facets and depth hoar near the ground and surface hoar layers in the upper snowpack. The problem was most common on northerly and easterly facing slopes earlier this month, along with some wind-loaded westerly facing terrain. After below-average snowfall for the last two weeks, these weak layers are expected to be temporarily dormant on most slopes, with the potential for isolated exceptions from the small amount of loading this weekend. The most suspect areas could be, extreme terrain, unsupported slopes, or previously wind-loaded terrain features. You can reduce your risk by traveling on south-facing slopes that have thick crusts, or by traveling on smaller terrain features without terrain traps.  You can avoid the problem on slopes consistently less than 30 degrees. 

    This large persistent slab was triggered by skiers descending the ridgeline on the Aspen side of the Elk Mountains last weekend, 12/17.  

Avalanche Discussion

In the Northwest Mountains, a weather station near Irwin and another in the upper Slate River drainage, are both showing storm totals near 8". Other weather stations are showing lower totals around 4". Over in the SE Mountains, storm totals only reached 3" and I suspect 4" exists somewhere. Wind speeds yesterday afternoon at 12,000ft, increased with averages in the teens and gusts into the 20's and 30's from the west to northwest. Overnight wind speeds remained generally light. SWE totals at Schofield Pass are .4", Lake Irwin .75" and Butte .3". That water weight isn't a significant load for the persistent slab avalanche problem. However, it is another loading test and we will be keeping our eye open for any surprises. The best guess would be an avalanche that releases where the 12/7 interface exists as buried surface hoar. 

Forecasted winds may increase at upper elevations tonight, and this will be something to keep an eye on for tomorrow. Wind speeds look to increase again later on Monday. Other than any potential wind-loading, there are no other weather factors driving the avalanche danger as we head into the start of next week. 

This video highlights some of the avalanche terrain that is on the naughty list vs the nice list. 

 

Avalanche Beacon Park Update:

Want to practice your avalanche beacon skills over the holidays? A practice area is currently set up behind the community school (located here). The control box that runs the normal park is out for repairs, but in the meantime, there are two beacons buried in the training park. Get out there and get some practice over the holiday!

Régions couvertes