Sawtooth & Western Smoky Mtns

Sunshine and warm temperatures will increase the threat of wet loose avalanches today. These slides are most likely on very steep, rocky slopes that directly face the sun. Isolated wind slabs exist in exposed, upper elevation terrain. Triggering a large avalanche involving one of these slabs is unlikely. However, even small wind slabs can have high consequences in very steep and rocky terrain.

Today will be a transitional day for the snowpack. The avalanche danger will start LOW but rise to MODERATE during the day. As the sun heats the snow surface liquid water will be introduced into the snowpack. This water weakens the bonds between grains of snow and decreases stability. In addition to the threat of sunburn, there are a few types of avalanche hazards related to today's clear weather:

• Dry new snow: The snow that fell in the last few days has had some short, passing doses of sunshine but it looks like it will be getting its full prescription filled today. This problem will be most likely in areas that have received the most snow in the past few days and where clouds have kept the sun at bay (Sawtooths, Western Smokys, and Banner Summit areas). As the sun warms up slopes for the first time, solar-initiated dry loose avalanches (sluffs) will be possible. These types of slides will generally be quite small but are a good prelude for the next step in the dance.
• Wet new snow: Direct sunshine and warm ambient air temperatures will allow for the fresh snow from the past few days to become wet. Initially, just the surface will be affected, but as the depth of the wetted horizon increases the likelihood, size and force of these types of slides will increase. On slopes that directly face the sun, stiff crusts underlie the new snow. These crusts will help these wet loose avalanches to pick up speed quickly. Because of this, slides that you trigger and those that start above you may run further than you expect. As with the dry snow problem described above, this type of slide is most likely in areas that received the most fresh snow. The very steep and rocky terrain that is common in the Sawtooths frequently produces large wet loose avalanches. 
• Wet old snow: At lower and middle elevations, the sun and heat today may be able to break down crusts that formed last week. As this happens, deeper gouging wet loose avalanches will be possible. You're most likely to encounter these on very steep, rocky slopes with a thin snow cover and those with trees that help add additional heat to the snow. If you can easily push your pole through much of the snowpack, or if the tail of your sled or bike drops deeply when you goose the throttle, you have likely found a snowpack where this type of problem is possible. I shot a short video north of Ketchum last week that shows these crusts and the weak snow underneath. Yesterday, Scott was able to create some large "snow snails" on a low angle slope in the Boulders, an indicator that the entire snowpack was becoming wet and unsupportable.
• Cornices: Several intense wind events have made up for the overall lack of snowfall this year and we have some significant cornices built across our forecast area. These huge chunks of snow become increasingly unstable as they sag and deform when the snowpack is close to its melting point. These unpredictable giants won't be up there forever—eventually they become unmoored from the ridgelines they are perched on. Be alert to the hazard they pose if you traveling below them and on ridgelines that are capped with them. Remember that it can be very difficult to accurately determine where a ridgeline stops and where a cornice starts.