Bulletin d’avalanche

Gunnison

Crested Butte Avalanche Center
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Danger d’avalanche

Sun
Alpin
1 · Faible
Limite forestière
1 · Faible
Sous la limite
1 · Faible
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Points saillants

Dry loose avalanches are our primary concern today on consequential and wind-protected northerly slopes.  If you're sinking up to your boots in loose, sugary snow, manage for small but pushy sluffs by riding away from the fall line or choosing mellower slope angles.  A very small chance remains for a triggered slab avalanche where you encounter stiff, previously drifted snow on leeward features at upper elevations; reduce your risk by steering away from old, hard drifts (like this avalanche in the Sawatch on Thursday). 

Problèmes avalancheux

  • Loose Dry

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

    The prolonged dry spell is causing the snowpack to lose cohesion on wind-protected northerly aspects, allowing sluffs to entrain more volume than you might expect in a few areas.  You are most likely to encounter gouging sluffs in terrain where the snowpack is shallowest and weakest: at low elevations or on slopes that avalanched last month.  Although most dry loose avalanches will be quite small and slow-moving, they can gather size and speed in sustained steep terrain.  Use sluff management techniques in steep terrain above trees, rock bands, and gullies where your skis are sinking deeply into weak, cohesionless snow.  You can avoid the problem on slopes with angles less than 35 degrees or by moving to terrain with a firmer or crusty snow surface.  

    Earlier this week, a skier hit a rock, lost a ski, and got carried by their sluff on Mt. Emmons.  This harmless situation could be more serious if you get pushed into a tree or a gulley.  

  • Persistent Slabs

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

    Previously drifted slabs remain a rare concern where they formed over buried facet layers and where the snowpack has remained mostly dry through the recent warmup.  Most slabs are typically 1 to 3 feet and can be identified by harder, smoother, or more rounded-looking snow on colder aspects.   Riding in terrain where the snow is soft and wind-protected, or dappled from wind erosion, offers a safer option.   

    An example of some hard wind-drifted slabs on the eastern side of Cinnamon Mountain. 

Avalanche Discussion

The peak of the heatwave has passed, and we're expecting a significant downturn in wet loose activity under today's cooler temperatures and increased winds.  Where thick surface crusts remain mostly frozen, they'll provide strength to the upper snowpack, further reducing lingering concerns for triggering an old hard slab on the sunny side of the compass - terrain that was most suspect a week ago. Crusts extending into the north side of the compass will also help narrow the number of slopes capable of producing dry loose avalanches.  For these reasons, all of the avalanche problems of the last few days are trending down now, and we're reaching a danger level where most slopes are safe from avalanches.  

Instabilities are expected to be either small, easy-to-recognize sluffs or rare hard slabs. Of course, people will be drawn to larger, steeper, and more consequential terrain as the danger dips into Low this weekend.  That's also the type of terrain where even a small avalanche can have serious consequences.  Don't let your guard down: use sound travel habits and manage for unstable snow in isolated areas.  Almost every year, we see one or two people get caught in facet sluffs during periods of drier weather and lower danger (e.g. this season, last season).  Here are some pointers in that regard: 

  • They start off quite slow and small - you might not even notice you triggered one as you're riding along (see video from Snodgrass).  Then they pick up enough volume and speed to hit you from behind as you stop to navigate a terrain feature or cut back underneath your sluff.  Good communication with your partners (radios are great!) can alert you if a point release is following you downslope, or practice sluff management techniques.  This video from a few years ago talks about strategies.  
  • Sluffs are most commonly found where the snowpack is shallow and unsupportive (the bullseye: below treeline close to town), and that's also where you're most likely to strike a rock or stump while you're skiing or riding. You can't manage your sluff if you just faceplanted into the snow.  Given our thin, weak snowpack, plan to manage both ground and avalanche hazards today. 

Régions couvertes