Bollettino valanghe

Gunnison

Crested Butte Avalanche Center
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Pericolo valanghe

Thu
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Conditions are steady eddy this morning as we wait for more new snow to accumulate. As a couple of inches of new snow adds up, the old wind-loaded persistent slab avalanche problem will become hard to identify as snow surface clues get buried. You can also expect any new snow to begin, adding volume to the dry loose avalanche problem, and to start creating shallow wind slabs in the alpine. 

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Strong northwesterly winds last week raked the mountains and mixed into typically more sheltered locations.  The incremental wind drifting built hard slabs ranging from just a few inches to several feet thick.  Although you can find these slabs at any elevation, we've seen the most significant wind loading and slab formation occurring nearing treeline, especially in terrain with large fetches favored by northwest winds.   These slabs are slower to heal because they formed above exceptionally weak facet layers.  They can also be remotely triggered from below or adjacent to steep slopes where the drifted snow spans onto lower slope angles.   The problem is localized to leeward terrain features and most often appears on the surface as smooth, dense, lens-shaped deposits behind tree fences, on the lee sides of ridged terrain features, and in concave catchments such as gullies.   Collapses and shooting cracks are clear warning signs of the problem.  Give wind-loaded terrain a wider berth than normal: there have been several near misses this week with some slides breaking into lower-than-usual slope angles.

  • Loose Dry

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–1.5

    Dry loose avalanches (sluffs) are a concern in wind-sheltered terrain on the north half of the compass.  Where the snow surface is weak and cohesionless, you can easily trigger sluffs that entrain the top 6" to 10" of loose snow on slopes steeper than 35 degrees. Ski cuts, moving across the fall-line while descending, or choosing lower-angled slopes are effective techniques to manage this problem. These point-release avalanches will accumulate more mass in long-running, steep terrain. Use caution above gullies where an avalanche can pile more deeply and above trees and cliffs where the consequences of getting caught in a small sluff will be magnified. This problem is most common in sheltered terrain below treeline, but you can also trigger sluffs on some near treeline slopes and a few above treeline slopes.    

Avalanche Discussion

If it doesn't snow today, it's because you didn't do your snow dance down Elk Avenue. Don't get busted by the CBAC Snow Police! If it does snow, well then we have some things to talk about...

We are expecting around 1 to 3 inches of new snow by 5pm this afternoon. The snowfall begins ramping up just before or a little after that timeframe with the arrival of a cold front. Based on those numbers I've expanded the loose dry avalanche problem. Any new snow today will begin adding volume to human triggered sluffs, and will begin to expand the avalanche problem to more areas that had previously quieted down. If enough snow adds up overnight, we can expect the loose dry avalanche problem to become a slab avalanche problem tomorrow. The old snow surface is exceptionally weak thanks to the extended 2022 drought. So if we get enough snow, conditions we begin to get interesting. 

The persistent slab avalanche problem caught several groups by surprise last weekend and produced some avalanches large enough to bury you. (Example: 1 & 2) Over the last few days, this avalanche problem was relatively easy to identify, by looking at snow surface clues to understand where those thick hard slabs had formed on previously wind-loaded terrain. Unfortunately, those snow surface clues are now being hidden by accumulating new snow. Consider giving wind-loaded terrain a wider berth than normal as you do not want to get surprised by a hard slab breaking above you and quickly pulling your feet out from under you. This isn't an avalanche problem that can be managed with ski cuts. 

Currently, the avalanche danger rating is not expected to change by a full level as we have been at the low end of Moderate for some time now. However, the avalanche problems and how sensitive they are to triggering will be changing by tomorrow. If accumulating snow exceeds the forecasted storm totals then we could see a rise to a CONSIDERABLE danger rating. The current storm doesn't look like a setup that will exceed the forecast, but we can still hope and you had better bet the CBAC team will be dancing hard today!

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