Lawinenlagebericht

Southeast Mountains

Crested Butte Avalanche Center
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Lawinengefahr

Fri
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

Westerly winds increased overnight and continued to load the lee sides of terrain featuers. In the last couple of days, there have been a few human-triggered avalanches on both wind-loaded and wind-sheltered terrain. Slab avalanches remain possible today in the same areas. Loose-wet avalanche activity will increase through the day as the sun and rising temperatures begin to wet the snow surface. 

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Slab avalanche concerns primarily exist on wind-loaded terrain. However, we can't completely rule out lingering storm slab issues in wind-sheltered terrain as well, where settled snow accumulations from earlier this week are over a foot deep. A layer of small facets was buried last weekend, and this layer is responsible for the most avalanche activity in the last few days. These avalanches have released on both wind-loaded slopes and a few wind-sheltered slopes. Consider avoiding wind-loaded terrain today, and further look for small test slopes where you can look for obvious signs of instability such as shooting cracks. 

    This avalanche was remotely triggered yesterday from the ridge above. The avalanche failed on small facets that were buried last weekend.

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    The new snow that accumulated earlier this week is transitioning into wet loose avalanches. This transition started yesterday and is expected to continue today. This avalanche activity will begin once the sun and rising temperatures have had a chance to wet the snow surface. This will occur first on easterly facing slopes, then move to southerly facing slopes and further onto westerly facing slopes. Some of these avalanches could become large in size. Watch for rollerballs, pinwheels, or natural sluffs to indicate developing instabilities, and move out of steep consequential terrain if the problem develops in your area. 

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–2.5

    In the Southeast Mountains, the last round of persistent slab avalanches occurred on March 16th. The most prominent weak layers are surface hoar buried a couple of feet deep and depth hoar near the ground.  The snowfall and windloading may increase the sensitivity of deeply buried weak layers.   Poor snowpack structure still exists in some areas and is commonly associated with a total snowpack height between 80 and 170cm. Persistent slab avalanches can be remotely triggered from low-angle terrain and break deeper and wider than you might expect.   Persistent slab avalanches are unlikely on 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 consider avoiding.  

Avalanche Discussion

We have seen some good snow totals adding up since last Saturday. The big winner was the Irwin area with a measured 34" of snow accumulating and 2.17" of SWE. Slightly less snow accumulated north of that area like the Slate River Drainage, and as another data point, Schofield Pass measured 1.4" of SWE for the same timeframe. Similar measurements were recorded in upper Brush Creek. With reports from the Friends hut totaling around 16 to 18" of settled snow and 1.8" SWE. CBMR is reporting 21" of snow. 

That snow has combined with a variable wind direction over the same period, Creating the largest loads on wind-loaded terrain. Most recently we have seen a wind direction from the west. Heading into this stormy period, we had a week of warm and dry weather. During the dry week, the snow surface on northerly facing slopes begins to facet. This observation is the best documentation of some of that weak snow. Now we are just starting to see a pattern of avalanches releasing on those buried facets. Such as this small avalanche in the Anthricites, these avalanches near Mt Axtell,  these couple of triggered avalanches near Purple Ridge, and a couple of triggered avalanches into Red Lady Bowl. These avalanches have all occurred on northerly-facing slopes. At the same time, there has been some steep skiing and riding on northerly facing terrain without resulting slab avalanche activity. So we don't have a widespread issue, but we certainly have enough documentation of a potential avalanche problem that warrants caution and consideration. 

All the snow reported above is also fueling our wet loose avalanche problem. This is a normal springtime avalanche problem, and we can expect that snow to continue transitioning from dry snow to wet snow while producing loose wet avalanches today. 

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