Bollettino valanghe

Southeast Mountains

Crested Butte Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

In the shallower Southeast Mountains, we have more concerns for triggering a large avalanche that fails on older weak layers. The safest riding is in wind-protected terrain in areas with a snowpack consistently deeper than about 6 ft or on southerly facing terrain.  Use extra caution on the north half of the compass in areas where the snowpack is around 3 to 5 feet deep, especially where the snowpack is variable in depth.  At higher elevations, stay alert for shallow but stiff drifts from unusual east winds.  They generally aren't large enough to bury you, but they could break above you and carry you into trees, rocks, or gullies. 

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    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.   Avalanches breaking into old weak layers are unlikely on mid to low-elevation, southerly aspects.  Slope angles consistently less than 30 degrees are a reliable way to avoid the problem.

    This large avalanche was remotely triggered in West Brush Creek on March 8th. 

  • Wind Slabs

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

    The past two days of east and southeast winds have drifted this week's snow into denser and thicker deposits on the leeward sides of gullies and ridges.  Read the surface textures to identify problematic features:  wind slabs will look smooth and rounded.  Consider terrain consequences and potential slab size before riding across steep, windloaded terrain.  

    A small wind slab on the lee side of a cross-loaded terrain feater. Mt Axtell, 3/14.

Avalanche Discussion

This week's major upslope storm made the news headlines for 3 to 4 feet of snow in the Front Range, but here in the rainshadow, we saw only modest snowfall (~5" to 10") and pesky easterly winds.  The wind slabs that formed during the past few days are neither large nor widespread, but enough to warrant caution in consequential terrain. Here are a few examples of the problem from Mt. Axtell and near Marble.  And because winds were blowing opposite their normal direction, expect to find drifts in unusual features.  Softer, wind-sheltered snow will provide safer and higher-quality riding today as we give wind slabs another day to heal up before they're likely pulled off the list tomorrow. 

Persistent slab activity has quieted down since March 9th.  Some of this may be attributed to fewer human triggers during a work week featuring grey weather.  However, a lack of significant loading and a cooler weather pattern this week are causing buried weak layers to become increasingly stubborn following a flurry of avalanche activity during last week's big storm and subsequent warmup.  Although the likelihood of triggering a persistent slab has declined, the consequences and our messaging, remain the same:  slopes with shallow and variable snow depths are most concerning.  That's where our buried surface hoar and early-season facet layers are both weaker and easier to impact. More slopes in the Southeast Mountains fit this description, though potential troublemakers exist in both forecast zones.  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), or by traveling on slopes with thick, supportive crusts near the snow surface (most commonly on the southern half of the compass).

CBAC Event:  The 50th Al Johnson Race is tomorrow! Registration is here.  All proceeds to benefit the CBAC.

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