Bridger Range

Recent snow from Tuesday was easily drifted by last night’s increased winds creating the main hazard today. In the Bridger Range these winds have been reaching down into low elevations. Recently formed wind slabs on top of older wind slabs will be the primary avalanche problem, and a persistent slab problem is arising with weak faceted layers in the snowpack and a growing soft slab of snow on top.

Avoid slopes loaded by these recent winds, and seek out sheltered slopes.. The dilemma this time of year when the snowpack is so thin is that we typically seek out slopes with the deepest snow, but those slopes are usually wind loaded and places where avalanches are more likely to happen.

Wind slab avalanches are the primary problem. Generally westerly winds have blown from the NW, W, & SW over the last five days transporting snow after each snowfall. Last night’s winds drifted Tuesday’s snow mostly at ridgelines but even at lower elevations in the Bridger Range. A wind slab avalanche that caught a skier in the northern Bridgers on Saturday is a good example of what to expect today. The good news is that you can usually identify wind loaded areas visually and simply avoid those slopes. The bad news is that many of these wind slabs are resting on weak facets which means they won’t stabilize any time soon.

A persistent slab avalanche problem is developing on slopes above 8500 feet in elevation. Slopes above that elevation held onto snow that fell in the latter half of October. Despite the warm fall weather, that snow remained very cold due to limited sunshine and clear, cold skies. That snow also became weak and faceted. It’s not the worst we’ve seen, but enough to be a problem now that a soft slab of snow is forming on top with snow that has fallen over about the last 10 days.

Now, the bottom half of the snowpack is generally weak and faceted with some ice crusts mixed in on sunny slopes. The top half of the snowpack is a soft slab of new snow. We have very limited data, but several observations near Cooke City have reported some collapses and shooting cracks which are clear warning signs of this persistent slab avalanche problem. Although we have limited data, we believe similar conditions exist in many other areas above 8500 ft. This problem will become more dangerous as snow falls this weekend and next week. 

With fresh snow drifted by last night’s winds, throughout the forecast area  the danger is MODERATE today for wind slab avalanches on wind loaded slopes. In some places these are at the highest elevations, while in the Bridger Range winds have been moving snow at all elevations.