Bollettino valanghe

Northwest Mountains

Crested Butte Avalanche Center
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Pericolo valanghe

Mon
Alta quota
4 · Forte
Limite del bosco
4 · Forte
Sotto il limite
4 · Forte
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In sintesi

The Elephant has arrived. Overnight the mountains got walloped by more heavy snow. Another natural avalanche cycle likely occurred during the early morning hours. Very large and deadly avalanches may continue to run naturally today, while other slopes are just hanging in the balance waiting for a trigger. Destructive avalanches could easily run far in the avalanche track, impacting flat terrain or some backcountry roads. Travel in avalanche terrain is not recommended.  

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    2–3.5

    Persistent weak layers in the middle of the snowpack and at the bottom of the snowpack are being overloaded by impressive snowfall in the last 5 days. Destructive avalanches are running naturally, and plenty of other slopes are just hanging in the balance. This avalanche problem will be the most reactive on north to east to southeast-facing slopes. Persistent slab avalanches can propagate widely through the terrain, or be remotely triggered from low-angle slopes connected to steeper slopes. 

    A large natural avalanche in Red Coon Bowl. 12/31.

  • Storm Slabs

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

    Recent avalanche activity has as been breaking in the new snow on some slopes. Warm and heavy snow has accumulated over colder and less dense snow. These slabs will most commonly release on slope angles in the mid-30 degree range and steeper. A triggered avalanche in the upper snowpack can also step down into the deeper persistent slab avalanche problem. 

    This widely propagating avalanche was remotely triggered on Saturday. You can see a shallower storm slab in the foreground and a deeper persistent slab in the background. 

Avalanche Discussion

My tail is definitely tucked this morning after looking at the recent loading event that happend in the last 12 hours. I no longer have doubts as to when we would see a more widespread natural avalanche cycle, and confidence has improved that the crap has hit the fan last night. Cowering and avoiding shrapnel may be some good travel advice. A decrease in accumulating snow today may slow some natural avalanche activity at below-treeline elevations, but the winds will keep loading near and above treeline start zones today and those natural avalanches could easily run into below-treeline elevations. 

Since last Tuesday, we have seen incremental loading, slowly adding weight and mass to the weak snowpack. The slower loading for a few days limited avalanche activity and left the forecast team wondering when the light switch would flip to a more active avalanche cycle. Since 12/27, Schofield Pass has accumulated 3.8" SWE and the Butte Snotel is at 2" SWE. Here is the kicker, in the last 12 hours Schofield increased 1.3 SWE and Butte .9 SWE. The last 12-hour rapid load was likely the final kick that we needed to see a more widespread natural avalanche cycle. The SWE measurement is the actual water weight of the snow. A foot of snow could fall anywhere between .8 and 1.2 SWE on average, depending on density. Upper elevation winds also increased out of the southwest during this time, further adding notable wind-loading into the mix. 

Previous to last night's rapid loading, notable natural avalanches were observed on Red Coon, and people remotely triggered avalanches near the Snodgrass Trailhead and Elkton.  

Multiple people were buried in avalanches yesterday in Colorado and unfortunately one of those resulted in the second avalanche fatality in the last week. Similar conditions exist in our area with potentially deadly consequences if you are caught in a slide. 

Happy new year to you all, unfortunately, we are not having fun this morning and coming to you with a serious tone. 

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