Boletín de aludes

Northwest Mountains

Crested Butte Avalanche Center
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Peligro de aludes

Sun
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Dangerous avalanche conditions exist and may worsen during the day from continued snowfall and wind.  Storm totals exceeding a foot coupled with efficient westerly winds formed sensitive slabs on leeward terrain.  Even steep sheltered terrain, where you find 8 inches or more of new snow, can produce avalanches in the storm snow.  Avoid traveling in drifted terrain and use caution in sheltered areas steeper than 35 degrees.  A very small chance remains for you to trigger an avalanche that breaks deeply in the snowpack on slopes that are rocky, shallower than 5 feet deep, or highly variable in depth due to previous winds.  

Problemas de aludes

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1–2

    Storm totals exceed a foot in the Northwest Mountains and more snow is forecasted on Saturday.  The most dangerous terrain for storm snow avalanches can be found on leeward terrain where westerly winds have loaded the new snow.  Some natural avalanche activity is possible today from wind loading or high-intensity snowfall.  Avalanches may be large enough to bury and hurt you.  In sheltered terrain, the new snow is accumulating on faceted surfaces that formed during this week's cold, dry period.  Caution is warranted in steep sheltered terrain as the new snow may not bond well to old surfaces.

    1/25: A skier triggered wind slab that broke about a foot thick on Ruby Peak.  Today, avalanches in the leeward terrain may grow larger and more dangerous than the one pictured here.  

  • Deep Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely
    Tamaño
    2–3

    On most slopes in the Northwest Mountains, faceted weak layers are buried deeply and unreactive to human triggers.  Some slopes have unusually shallow or variable snow depths where riders may be able to trigger a hard slab several feet thick or more.  Be cautious of windward terrain features with variable depths, rock bands, and slopes that previously avalanched in early December where you are most likely to find a thin trigger point.   The safest riding is where the snowpack is uniform and consistently deeper than about 5 feet (150 cm).  

     

    This avalanche was triggered by explosive work in the Irwin Cat-Ski tenure on Thursday, 1/26.  It is representative of the type of terrain (shallower than normal, full of trigger points, and unsupported from below) where an unlikely chance remains for you to trigger a deep avalanche.

Avalanche Discussion

Mother nature delivered yesterday and deposited more than a foot in the Northwest Mountains, 9 inches at CBMR, and lesser amounts to the east.  Southwest-to-west winds have blown the new snow to leeward terrain features.  With additional snow and wind today, expect problems with the storm snow to increase throughout the day if the weather forecast verifies or is exceeded.  Drifted terrain is the most likely place for you to trigger an avalanche today and some avalanches may run naturally.  In sheltered areas, you can expect steep terrain to produce Loose Dry avalanches and there is the possibility for some Storm Slab activity if the new snow bonds poorly to the old surfaces.

There is a greater hazard where you find more snow which makes conditions worse in the Northwest Mountains, but areas in the Southeast Mountains that border the Northwest Mountains, you may find just as dangerous conditions,  For example, the swath of terrain from Mount Emmons to Anthracite Mesa to Gothic  Mountain received similar amounts to the Northwest Mountains.

Triggering an avalanche deeper in the snowpack (Deep Persistent Slab problem) remains an unlikely problem in the Northwest Mountains, but is a worthwhile consideration in your terrain selection.  Given the issues with storm snow, your safest bet is to stick to sheltered terrain with a deep uniform snowpack and this will help reduce the risk of avalanches in the storm snow and on deep weak layers.

Avalanches breaking deeper in the snowpack (Persistent Slab problem) is possible in the Southeast Mountains.  This storm is not expected to significantly worsen Persistent Slab concerns, but the potential remains for areas with a shallower snowpack, less than 5 feet, to produce a deeper failing avalanche.  Keep in mind that some slopes may be shallower due to previous avalanche activity.  This observation from lower Wolverine Basin on Mount Emmons is a good example of the weak snowpack you can find on some slopes that previously avalanched.  If you are uncertain about triggering an avalanche deep in the snowpack simply choose terrain 30 degrees or less that isn't connected or below steeper terrain.

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