Good Morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Advisory issued on Sunday, April 2nd at 7:05 a.m. Today’s advisory is sponsored by Mystery Ranch and the Gallatin Valley Snowmobile Association. This advisory does not apply to operating ski areas.
At 5 a.m. the mountains near Big Sky and Hyalite have 2-3” of new snow with a trace elsewhere. Temperatures are high 20s to low 30s F with west to northwest wind at 5-15 mph. Today, temperatures will reach low 30s with west to northwest wind at 10-20 mph. Thunderstorms are possible this afternoon with light snow and rain through the day. Tonight, temperatures will drop to low 20s and teens F and the mountains will get 1-3” of snow by morning with 3-5” possible near Cooke City.
Bridger Range Madison Range Gallatin Range
Lionhead area near West Yellowstone Cooke City
Snow, wind, sunshine, and warm temperatures created heightened avalanche danger this weekend (video, video). Today, more snow and possibly rain contribute to the mix of avalanche problems to look out for. Eric was near Bridger yesterday and summarized conditions as “full on spring”. He noted wet loose avalanches that ran far over cliffs (photo), while the wind transported recent snow into drifts on the ridgeline. I found similar conditions near Cooke City where we avoided wind slabs near the ridge and triggered small wet loose avalanches lower on the slope.
Recently formed wind slabs are possible to trigger today. Avoid steep slopes near ridgelines and below cliffs where snow is commonly drifted. A group of climbers triggered a wind pocket below cliffs near Beehive Peak yesterday. They were not caught, but it was a close call (photo, photo, photo). On Friday, a skier on Mt Blackmore triggered a wind slab that broke 1’ deep and 30 feet wide (photo).
Wet snow avalanches are possible if rain falls this afternoon or warm temperatures create a moist snow surface. Below freezing temperatures this morning formed a frozen snow surface, which is below a few inches of new snow in some areas. Loose snow avalanches are possible in the new snow and could run far on the frozen crust below. If rain falls or the snow surface gets wet, avoid steep terrain. Be aware of terrain overhead that could produce natural slides, such as steep slopes near cliffs and rocky outcrops. Fresh roller balls and natural wet loose avalanches show the snow is losing strength and unstable (photo, photo). If you see these signs avoid similar terrain, and move to shadier aspects.
Recent snow, wind, and potential rain today make avalanches possible. The avalanche danger is MODERATE.
I will issue the next advisory tomorrow morning by 7:30 a.m. Our last advisory of the season will be Sunday, April 9th.
We rely on your field observations. Send us an email with simple weather and snowpack information along the lines of what you might share with your friends: How much new snow? Was the skiing/riding any good? Did you see any avalanches or signs of instability? Was snow blowing at the ridgelines? If you have snowpit or test data we'll take that too, but this core info is super helpful! Email us at mtavalanche@gmail.com or leave a message at 406-587-6984.
MAY 4: Give Big Gallatin Valley
The Friends of the Avalanche Center are one of the recipients of the Give Big Gallatin Valley campaign. It is a 1-day fundraising event for local non-profits on May 4, so mark your calendars. The Friends will send reminders as the day approaches: https://www.givebiggv.org/organizations/friends-of-the-gallatin-national-forest-avalanche-center