Lawinenlagebericht

Southeast Mountains

Crested Butte Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

Saturday's large natural avalanche off of Mt. Crested Butte (see video) demonstrates our ongoing concerns for triggering a persistent slab that fails several feet deep: choose terrain carefully on the north half of the compass in areas where the snowpack is around 3 to 5 feet deep, especially in variable or rocky areas.  The safest riding is in wind-protected terrain in areas with a snowpack consistently deeper than about 6 ft.  On steep, sunbaked slopes, manage for shallow wet avalanches once the snow surface gets wet or starts to rollerball.

Lawinenprobleme

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    Sunshine and warming temperatures will increase the threat of shallow wet avalanches involving the recent snow.  Watch for rollerballs, pinwheels, or natural sluffs to indicate developing instabilities first on east, then south, then west aspects.  Natural sluffs are most likely to initiate from very steep or rocky slopes.  Be careful in or above consequential terrain once the snow surface gets wet or sticky.  You can avoid triggering wet loose avalanches by riding on slope angles less than 35 degrees or moving to colder aspects.  

    A small wet loose avalanche from earlier this week.

    (3/16/2024)

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–3

    In the Southeast Mountains, high-consequence slabs breaking on older weak layers are becoming more difficult to trigger but remain a concern on the north half of the compass, or potentially on a few southerly slopes above treeline.  The most prominent weak layers are surface hoar buried a couple of feet deep and depth hoar near the ground.   Persistent slab avalanches can be remotely triggered from low-angle terrain and break deeper and wider than you might expect.   Triggering avalanches are unlikely on mid to low-elevation, southerly aspects, or areas where the snowpack is consistently deeper than 200 cm.  Slope angles consistently less than 30 degrees are a reliable way to avoid the problem.

    A large persistent slab on Mt. Crested Butte that ran on 3/16.  This slope is shallow, variable in depth, and on the north half of the compass: a combination of ingredients you want to avoid.  

Avalanche Discussion

In the Northwest Mountains, we bumped the danger back up to Moderate today due to increasing concerns for wet loose avalanches.  Periods of sunshine and greenhousing earlier this week spurred some wet loose activity up to D1.5 in size.  We have some uncertainty about whether today's wet instabilities will be hazardous enough to increase the danger: some slopes have run their course and easterly winds scoured other slopes.  However,  with significantly greater amounts of solar warming today relative to earlier this week, we erred on the side of caution to see how today's wet loose activity plays out.  Regardless, wet instabilities are fairly easy to recognize and avoid with spring travel protocols and terrain selection.  

On the shady side of the compass, you'll find drier snow but have to manage for the larger threat of slab avalanches breaking on older weak layers.  This issue is most concerning in our shallower Southeast Mountains.  The most recent example is a natural avalanche in Terminator Chutes on Saturday evening.  This observation from Saturday demonstrates how slopes with a deeper snowpack are relatively stronger and more trustworthy.  You can significantly reduce the risk of triggering a large avalanche by traveling where the snowpack is consistently deeper than about 200 cm (~6 feet).  If you're looking to step out into big alpine terrain this week, the deeper snowpack of the Northwest Mountains is generally a safer choice right now. 

Thanks to everyone who helped out or participated in the Al Johnson yesterday. We appreciate the community support and love to see all the great costumes!

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