Good morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Advisory issued on Thursday, January 28, at 7:00 AM. Today’s advisory is sponsored by Yellowstone Club Community Foundation and Soda Butte Lodge. This advisory does not apply to operating ski areas.
Over the last 24 hours, temperatures reached the mid-30s F in the northern mountains and mid-20s F in the southern mountains. Temperatures this morning are in the high-teens F in the south and low-30s F in the north. Wind is blowing west-southwest at 15-20 mph with gusts in the 30s. Today will be mostly sunny with temperatures in the 30s F. Wind will remain out of the west-southwest with speeds increasing to 30 mph this afternoon. Light snow will begin tonight with 1-3” by morning, and another 3-6” is possible tomorrow night.
Bridger Range Madison Range Gallatin Range
Lionhead area near West Yellowstone Cooke City
The mountains have not received any new snow in the last 72 hours. Prior to yesterday, plenty of new snow was available to be transported by strong winds to form wind slabs. These pillows of windblown snow are less likely to trigger today than they were over the prior two days.
Instabilities due to new and windblown snow earlier this week have now subsided. However, the snowpack still consists of a poor structure that is capable of producing avalanches (video). Sugary weak depth hoar at the ground exists throughout the advisory area. It is difficult to trigger an avalanches on this layer, but it cannot be trusted. An avalanche on this layer will be large and bring down a thick slab of the entire season’s snowpack (video). In some areas, another weak layer of facets exists 1-2 feet below the surface. These weak layers may not display obvious signs of instability, but natural and human triggered avalanches have failed on these layers in the past week (photo, photo, photo). Areas where it is more likely to trigger an avalanche include wind loaded slopes where weak layers have been stressed by more load, convex rollovers, and shallow areas near rock outcrops or the edges of the slab.
Due to a poor snowpack structure human triggered avalanches are possible. The avalanche danger today is rated MODERATE on all slopes. Avalanches have the potential to be large. Practice cautious route finding and conservative decision making.
I will issue the next advisory tomorrow morning by 7:30 a.m. If you have any snowpack or avalanche observations to share, drop us a line at mtavalanche@gmail.com or leave a message at 587-6984.
EVENTS and AVALANCHE EDUCATION
A complete calendar of classes can be found HERE.
West Yellowstone: Saturday, January 30, 1hr Avalanche Awareness, West Yellowstone Holiday Inn, 7-8:30 p.m.
Cooke City: Saturday, January 30, Companion Rescue Clinic for Snowmobilers. Information and registration here: https://www.ticketriver.com/event/18078
Lewistown: Saturday, January 30, 9:00 a.m., 1hr Avalanche Awareness for Snowmobilers, Lewiston Honda-Polaris. More information can be found HERE.
EVENT at BRIDGER BOWL: February 6, King and Queen of the Ridge. A day of hiking and skiing the Ridge as a fundraiser for the Friends of the Avalanche Center. Teams and individuals are welcome! More info here: http://bridgerbowl.com/event/king-and-queen-of-the-ridge