GNFAC Avalanche Forecast for Thu Mar 18, 2021

Bridger Range

Gallatin Range

Madison Range

Lionhead Range

Island Park

Wet avalanches are our main concern today. Yesterday's temperatures reached the 40s and sunny slopes moistened but held together. There were no widespread loose avalanches. On slopes that were shady the snowpack is still cold and wintry. Today will be a few degrees warmer, yet a breeze might provide enough cooling to keep avalanche activity in check. It will take a couple hours for the frozen surface to soften up and in general I expect small, wet loose avalanches on sunny slopes. The interplay of elevation, aspect and timing is critical because the snow surface and avalanche danger can change rapidly. Ian explains it further in his video from Lionhead. 

You don’t need a compass or watch to inform you where and when slopes become unstable, just pay attention. Sunny slopes will get wet and gloppy. The more intense the sun is, the wetter slopes will become. A sign that wet avalanche danger is rising is sinking past your ankles in wet snow or seeing large pinwheels of snow rolling downhill. 

Dave was in Taylor Fork and Lightning Creek yesterday and had 3 things on his mind: wet avalanches, a potential new weak layer at the surface if it gets buried (near-surface facets), and also sugary depth hoar near the ground which broke in his test (video). The wet snow is the primary concern today, but the other two may become problems when it snows Friday night. 

For today, the wet snow avalanche danger will start out LOW but rise to MODERATE on slopes that become wet and slushy. 

The dry snow avalanche danger is rated LOW on all slopes because avalanches are unlikely.

Cooke City

The mountains outside Cooke City reached the low 40s yesterday. Today will be a few degrees warmer and sunny slopes will get moist and shed surface snow in wet loose avalanches. Wind is expected to keep the snow surface cool which will inhibit avalanches becoming widespread. On slopes not affected by the sun the snowpack is dry and mostly stable (video of current conditions from Tuesday).

For today, the wet snow avalanche danger will start out LOW but rise to MODERATE on slopes that become wet. 

The dry snow avalanche danger is rated LOW on all slopes because the snowpack lacks buried weak layers and avalanches are unlikely. 

If you get out, please send us your observations no matter how brief. You can submit them via our website, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).