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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Veraltet — dieser Lagebericht ist 5 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Last night's 1 - 4 inches and an additional couple inches today will maintain the slow, continuous loading of the snowpack since Sunday.  Westerly winds are transporting snow at upper elevations.  Today you will need to manage freshly drifted snow and the potential for triggering a deeper large avalanche.  Avalanches failing deeper in the snowpack is a problem relegated to northerly aspects, particularly drifted features (skier-triggered avalanche from Wednesday) or slopes the previously avalanched in February.  On sunny slopes, small triggered avalanches are possible where you find about 8" or more of drifted snow on leeward terrain. 

Lawinenprobleme

  • Persistent Slabs

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

    The past week has brought a steady string of near misses and unintentionally triggered soft slab avalanches that released on buried weak layers one to two feet deep (Sunday 1, Sunday 2,  Thursday, Wednesday), along with several naturals (Example A, Example B).  You are most likely to encounter this problem on steep, shaded terrain with variable or thin snowpack depths. Most of the recent avalanches are repeating in paths that ran back in February and have since refilled with snow and wind transport.  Be cautious of higher elevation slopes that look like they have a below-average snowpack (evidenced by more rocks or small trees), or if you see faint old crown lines.  You can reliably avoid the problem on sunny aspects where the snowpack has a stronger spring-like structure.

    3/18: A skier was caught by surprise by this persistent slab on Mt. Axtell.

  • Wind Slabs

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

    An increase in westerly on Wednesday night coupled with available snow for transport will create a small Wind Slab problem today.  Winds will shift from west to southwest as the day progresses.  Look for drifting below ridgetops, underneath cornices, tucked behind ribs, or adjacent to scoured areas.  Avalanches in the recently drifted snow are expected to remain small in size, but keep in mind that beneath the fresh drifted slabs are older weak layers that could fail from a triggered Wind Slab.

    Blowing snow and cornices help indicate locations where fresh, wind-drifted slabs are forming. You can see small Wind Slabs ran naturally below the cornice. Photo from earlier this winter.

Avalanche Discussion

Another round of light snowfall continues to add to this week's accumulations.  Rough totals since last Saturday night range from 6" to 20" with CBMR reporting around 11" and Irwin leading the pack around 20".  The slow trickle of accumulations can be challenging to keep track of and seem insignificant, but on shaded slopes, the accumulations are starting to raise concerns with the Persistent Slab problem.  Yesterday, a skier triggered a small avalanche the broke in older snow from mid-March.  This triggered avalanche may be the "canary in the coalmine" example of things to come with a moderate storm moving into the area.  For today, most concerns for triggering an avalanche deeper in the snowpack will be on drifted features with a northerly tilt and on shaded slopes that previously avalanche in February.  With additional loading from an uptick in winds overnight and today, expect the sensitivity of this problem to slowly rise as more snow is deposited by the wind on leeward features.  As the snow begins stacking up later this afternoon expect the avalanche hazard to rise and the sensitivity of the Persistent Slab problem to increase.  Weather models suggest that the heaviest precipitation will fall after sundown, but be prepared to adjust your terrain selection late in the day if the stronger precipitation arrives earlier than expected.

Sunny slopes are generally free from Persistent Slab concerns as meltwater has previously moved through much of the snowpack and refrozen or drained.  Sunny slopes will present a Wind Slab problem in areas where you find wind-transported snow, but with west to southwest winds, much of the Wind Slab problem will develop on slopes that face north through east.  Expect the size of wind drifted slabs to increase later in the day as snow accumulates.

The incoming storm is looking promising for the Crested Butte area particularly for areas west of town and should provide a nice refresh to riding conditions.  Avalanche conditions have allowed some folks to step into bigger and more consequential terrain,  but if the weather forecast verifies for this storm expect the need to reel in your terrain choices and move towards a more conservative mindset.

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