GNFAC Avalanche Forecast for Tue Apr 15, 2025
This is Dave Zinn with the avalanche forecast on Tuesday, April 15th, at 6:30 a.m. sponsored by Polaris and the Yellowstone Club Community Foundation. This forecast does not apply to operating ski areas.
This morning, temperatures are near 30 degrees F with 5-15 mph winds from the west and southwest. Clear skies overnight allowed longwave radiation to escape into the atmosphere and snow surfaces to refreeze.
Today, temperatures will be 10 degrees F warmer than yesterday, with highs nearing 50 F in Cooke City and rising well into the 50s F across the rest of the forecast area. Winds will be 5-15 mph from the west and southwest. A few clouds will move into the area this evening, but the change in weather arrives tomorrow afternoon when low pressure arrives from Canada and with it, colder temperatures and a chance for more than a foot of new snow.
In Cooke City, fresh snow from the weekend experienced its first significant warm-up with above-freezing temperatures and intense April sunshine yesterday. Similar weather today will repeat the cycle. Wet loose avalanches, both natural and human-triggered, are likely on steep, south-facing slopes. These avalanches typically begin at a point and expand as they collect snow. Rocks and cliff bands often serve as their starting points. Steep, confined terrain poses the greatest risk because snow running downhill has limited room to spread out. Thankfully, wet snow hazards are easy to identify and avoid. Transition to cooler, shaded north-facing slopes before the day’s warmth destabilizes the snow. Conditions are becoming unstable when the upper few inches of snow get moist, roller balls trickle downslope and small wet snow avalanches dribble out of rocky areas.
Over the weekend, strong winds created snow drifts up to two feet thick. While these wind-loaded slopes stabilize relatively quickly, human-triggered wind slab avalanches remain possible, especially in high elevation terrain where the surface snow remains dry and cool. Either avoid obviously wind-loaded slopes or assess their stability by watching for shooting cracks and performing a quick extended column test - you only need to dig down to the thick underlying crust, 1-2 feet deep (how to video).
The avalanche danger in Cooke City is MODERATE.
Temperatures in the Bridger, Madison, Gallatin, Lionhead and Centennial Ranges will reach the mid-50s F. The primary concern is wet loose avalanches this afternoon, and the focal point for instability is steep rocky slopes with uncompacted snow on southerly aspects (southeast through west). Wet loose slides are mostly a hazard in very steep or extreme terrain, where they could push a skier or rider into obstacles or terrain traps. If you notice pinwheels of snow rolling downhill or small wet slides, move to cooler, shaded northerly aspects to reduce exposure.
Stay situationally aware when traveling above and below large overhanging cornices, as they tend to break off periodically during warm spring days.
Other than small wet snow avalanches on sun-exposed slopes, the snowpack is generally stable, and dry snow avalanches are unlikely. The danger is LOW and will rise to MODERATE on the specific slopes where snow surfaces get wet.
If you encounter an error with our observation submission platform, please email your observations to mtavalanche@gmail.com
Hyalite Road Closure
The Hyalite Canyon Road is closed to ALL MOTORIZED VEHICLES until May 16. This is a regular annual road closure to reduce road damage during the spring thaw. Bicycle and foot traffic are allowed. Contact the Bozeman FS Ranger District for more info.
Bridger Bowl Ski Area is closed for the season, and uphill travel is allowed. Please give employees and machinery plenty of room as they work to clean up from the season. Backcountry conditions will develop as spring storms impact the range. There are no ski patrol services, avalanche mitigation or terrain closures as conditions evolve. Call 911 for any incidents requiring outside assistance.
Our last daily avalanche forecast will be Sunday, April 20th. We will issue updates on Mondays and Fridays through the end of April.