GNFAC Avalanche Forecast for Tue Mar 3, 2020

Good Morning. This is Dave Zinn with the Gallatin National Forest Avalanche Forecast on Tuesday, March 3rd at 7:00 a.m. Today’s forecast is in memory of Ben Richards. Ben was killed in an avalanche thirteen years ago today. He will be forever missed and remembered. This advisory does not apply to operating ski areas.

Mountain Weather

Last night the mountains received 1-3” of new snow. Winds averaged 15-30 mph from the west to southwest and gusted up to 65 mph at the Flanders weather station in Hyalite Canyon. This morning temperatures are in the teens to low 20s F. Today winds will blow 25-35 mph from the west in the northern ranges and 15-20 mph in the southern ranges. Temperatures will climb into the 20s to low 30s F. This morning Cooke City will receive a 2” of snow with a trace elsewhere before skies clear this afternoon.

Snowpack and Avalanche Discussion

In the northern ranges moderate to strong winds gusted to 50 mph and 65 mph in Hyalite Canyon. These winds are building fresh drifts of snow and increasing the size of already enormous cornices. While the 1-3” of new snow won’t add much widespread stress to the snowpack, it will provide ammunition for wind loading. Yesterday at Buck Ridge we triggered a 6” deep wind drift on a small test slope. We also observed a natural cornice collapse in Second Yellowmule. Avoid these behemoths as they can fail much farther back than expected (video). Additionally, cornice collapses may trigger deeper avalanches on slopes below. This story played out in the Hourglass Chute north of Bridger Bowl last Thursday (photo). Deep instabilities are less sensitive without a more significant load, but triggering avalanches on weak facets near the ground is still possible. We rode conservatively yesterday because of this possibility and less than a week ago a backcountry trail groomer triggered an avalanche on this layer that rolled the snowcat and driver 165 feet down the hill (video, photo and details).

Today, avoid wind loaded slopes and avoid cornices while maintaining a healthy fear of the less likely possibility of avalanches breaking on deeply buried weak layers. Human triggered avalanches are possible and the danger is MODERATE.

The Last Word

Get tickets for the 21st Annual Powder Blast Fundraiser on October 25th at The Emerson Ballroom.