Northwest Mountains

You can trigger a large avalanche in places where the snowpack is thinner due to wind effects, rocky slopes, or areas that simply received less snowfall this winter.  Cooler temperatures and increasing cloud cover on Thursday have reduced the threat of avalanches on many sunny slopes as supportive surface crusts now exist.  You can reduce your risk of triggering an avalanche by choosing slopes with consistent snowpack depths around 5 feet or greater and below treeline where snowpack depth is more uniform.

Recent natural avalanche activity around Crested Butte has largely been on south and westerly aspects.  Much of the recent activity is attributed to the warm temperatures and sunshine weakening the snowpack (examples of recent avalanches on sunny slopes).  Cloud cover is forecasted to increase dramatically during the first half of Thursday which should prevent surface crusts on sunny slopes from softening.  Supportive crusts on sunny slopes will greatly reduce the chance of you triggering an avalanche which is reflected by the removal of some sunny aspects from the Persistent Slab distribution rose above.  

The most likely places for you to trigger a large avalanche are on west through north through east aspects and some high elevation sunny slopes where you find a shallower snowpack.  A shallower snowpack could be from less snowfall this winter which you are more likely to encounter in the Southeast Mountains forecast zone.  Thin spots or shallow areas can form on wind-affected slopes as well.  You are more likely to find shallow spots (trigger points) near and above treeline where the wind has a greater impact.  An example of the variable depth in wind-affected terrain can be seen in this triggered avalanche from the San Juans on Tuesday.  The variation in depth left part of the slope shallower than the rest making it easier for this rider to trigger an avalanche.  It can be challenging to estimate snowpack depth across a large slope which makes for tricky decision-making in wind-affected terrain. 

Choosing terrain where the snowpack is deeper, greater than about 5 feet, and uniform in depth will reduce your chance of triggering an avalanche.  The danger rating was dropped to LOW below treeline in the Northwest Mountains as low-elevation sunny slopes are less likely to produce avalanches after the recent warm weather and northerly slopes below treeline have a deeper and more uniform snowpack.  The danger rating remains MODERATE below treeline in the Southeast Mountains as depths are generally shallower and leave an increased risk of triggered avalanches on sheltered slopes on the north half of the compass.

A storm is knocking at the door and is forecasted to arrive Thursday night and last through the weekend.  Recent observations have noted large surface hoar and weak near surface facets on the north half of the compass at all elevations and slick sun crusts on most southerly slopes.  Expect the avalanche danger to rise as snowfall accumulates particularly on northerly terrain where fragile weak layers will struggle to support even modest storm totals.  Take a look at this video to see the snow surfaces the incoming storm will fall on.

Events: Our next Fireside Chat is this Sunday, February 4 at 6 p.m. at High Alpine Brewing Company in Gunnison. A local snowmobiler will talk about his experience with an avalanche burial and rescue while snowmobiling last year.