Good Morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Thursday, April 6th at 6:30 a.m. Today’s advisory is sponsored by Excel Physical Therapy and the Community Food Co-op. This advisory does not apply to operating ski areas. Bridger Bowl is closed for the season and has backcountry conditions.
This morning temperatures are in the upper 20s to low 30s F and winds are blowing 10-20 mph out of the W-SW with ridgetop gusts around Big Sky breaking 30 mph. Today, temps will be 5-10 degrees warmer than yesterday with highs reaching the upper 30s to low 40s F. Winds will increase out of the W-SW with ridgetop gusts pushing 40 mph by this afternoon. Skies will remain partly to mostly cloudy and there’s an increasing chance of precipitation this afternoon. Some areas may even see isolated thunderstorms as a weak system moves through the area. Tomorrow looks to be another unsettled day with the potential for valley rain and mountain snow.
Yesterday, cooler temps and cloudy skies kept the wet snow avalanche danger at bay. Today, warmer temps and periods of sun could produce wet loose avalanches on sun exposed slopes. Roller balls and pinwheels are the first sign that wet-loose avalanches can quickly follow video. Fortunately, partly to mostly cloudy skies combined with strong winds should keep conditions cool enough to prevent a widespread wet loose avalanche cycle.
A dry snow avalanche hazard still exist in high alpine terrain. Isolated wind slabs below upper elevation ridgelines are the main concern (photo). As winds pick up today, available snow will be transported onto leeward slopes, which could form a fresh batch of small wind slabs (photo). If you’re traveling in alpine terrain, watch for active loading and avoid steep slopes that appear to be wind loaded.
An additional concern is cornices. These large overhanging chunks of snow can fail naturally or with human triggers. Yesterday, a skier outside of Cooke City had a close call when he fell into a large crack formed by a cornice peeling away from the ridge. Fortunately, he did not fall through the cornice and was able to climb out. This is a good reminder to give these monsters more space than expected along the ridgelines and also to avoid slopes directly below.
For today the wet snow avalanche danger will start out LOW but rise to MODERATE by this afternoon. The dry snow avalanche danger is rated LOW.
Doug 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