Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Tuesday, March 17th, at 7:30 a.m. Mystery Ranch in partnership with the Friends of the Avalanche Center sponsor today’s advisory. This advisory does not apply to operating ski areas.
At 5 a.m. the mountains around Cooke City are showing five inches of dense snow, an inch around West Yellowstone and a trace everywhere else. Under cloudy skies winds are blowing out of the west to southwest at 10-15 mph with gusts of 20-30 mph. The Bridger Range has east winds this morning, but will switch to southwest as the day progresses. Mountain temperatures are in the mid to upper 20s. Precipitation will continue and by tomorrow morning the mountains could have 2-4 inches with closer to 6 inches in Cooke City, and additional snow falling on Wednesday. The freezing line will rise to 8-9,000 feet today, so be prepared for some drizzle when you step out of the car.
Bridger Range Madison Range Gallatin Range Lionhead Area near West Yellowstone Cooke City
At upper elevations last night’s cold temperatures will help the snow stability. Lower elevation slopes will be unfrozen and mushy while upper elevation starting zones will form a melt-freeze crust. We had almost four days of above freezing temperatures which started to break down the snowpack structure into a mass of moist snow that could not support bodyweight. People reported sinking to the ground in wet snow. Yesterday there were a few wet slides reported in Cooke City and a few small, wet loose avalanches in the Bridger Range. Eric and his partner skied to the top of the Ramp north of Bridger Bowl and found three days of above freezing temperatures had a negative impact on the snowpack (video).
The freezing line will determine snow stability. If it rains wet avalanches are possible. If it snows avalanche activity will be minimal. It was cold enough in the mountains around Cooke City to drop five inches of snow last night (.6 inches of snow water). This moist new snow will stick to slopes and not pose a big problem. It’s a mixed bag of conditions which means there’s not just one avalanche concern: moist snow underneath the frozen crust, rain on lower elevation slopes and new snow outside Cooke City. Today the avalanche danger is MODERATE on all slopes, but if it rains the danger will quickly rise to CONSIDERABLE.
I will issue the next advisory tomorrow morning at 7:30 a.m. If you have any snowpack or avalanche observations drop us a line at mtavalanche@gmail.com or call us at 587-6984.