Lawinenlagebericht

Northwest Mountains

Crested Butte Avalanche Center
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Lawinengefahr

Mon
Hochgebirge
1 · Gering
Waldgrenze
1 · Gering
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 5 months ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Extreme winds and a dusting of new snow could form isolated drifts in unusual locations.  Carefully read the snow surface to identify hard wind deposits and steer around them to manage the hazard.  On the northern half of the compass, triggering an avalanche on weak layers deeper in the snowpack is unlikely, but not impossible.  Avoid areas where you might find a trigger point, such as rocky areas, convex rolls, or slopes with shallower-than-average coverage.

Lawinenprobleme

  • Persistent Slabs

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

    Old, hard slabs 2–3+ feet thick linger over buried weak layers but are becoming increasingly stubborn to trigger and less common. Without obvious warning signs, avalanches are most likely triggered where the slab is thinner and easier to impact the weak layer below. The most fragile layers are buried in the middle and lower portions of the snowpack on northerly aspects. Persistent slab avalanches can propagate widely and be remotely triggered from adjacent low-angle terrain. One way to reduce the chance of triggering is by avoiding steep terrain with a thin or variable snowpack, such as rocky areas, rollovers, or places where winds have created uneven slab thickness. Triggering is the least likely in areas with a consistently deep snowpack across the terrain. 

    This was the last Persistent Slab avalanche observed in the NW Mountain FX area. It released ( 2/28) below a cornice on a steep face that has avalanched multiple times this winter. 

Avalanche Discussion

The disturbance rolling through Colorado delivered a lot more wind than snow and cold temperatures.  It's difficult to know how much snow accumulated, but an inch or two is a good bet.  Isolated slabs may form across the landscape from the extreme winds.  Gusts have commonly exceeded 60 mph, with a few gusts above 100 mph.  The distribution will likely be isolated across the landscape and small in size.  Drifts may form in uncommon places, so keep a watchful eye on concave features and behind windbreaks like trees, ribs, or ridges.

The cooler temperatures will cut off the threat of wet avalanche activity.  Unfortunately, southerly aspects have been a go-to terrain choice for many folks thanks to quality riding conditions and a low threat of slab avalanches.  Expect to find most terrain features locked up on Sunday, with little hope of softening due to cold temperatures and strong winds.

On the northern half of the compass, there is a lingering threat of slab avalanches breaking a week layers 1 - 3 feet deep.  The likelihood of triggering a persistent slab avalanche has slowly decreased over the past few weeks of relatively warm and benign weather.  Although the probability continues to decrease, you can't rule out triggering a dangerous avalanche.  This natural avalanche on Mount Whetstone likely ran early this week during a period of wind drifting.  Poor structure and a recent large natural avalanche support the MODERATE danger rating in the Southeast forecast zone.  Slabs are often thinner and weak layers better developed in the Southeast Mountains.  In the Northwest Mountains, the danger rating has dropped to LOW; however, poor snowpack structure exists on many northerly-facing slopes around the range.  This poor structure keeps the unlikely threat alive in the Northwest Mountains.

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