Good Morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Advisory issued on Sunday, February 18th at 7:00 a.m. Today’s advisory is sponsored by Grizzly Outfitters in partnership with The Friends of the Avalanche Center. This advisory does not apply to operating ski areas.
Since yesterday morning the mountains near Cooke City got 14” of new snow. Near Big Sky, Hyalite, and West Yellowstone got 7-10”, and the Bridger Range got 4”. Wind was southwest at 25-40 mph with gusts of 60-80 mph yesterday, and decreased to 20-30 mph out of the west this morning. Temperatures this morning are teens F and will drop to single digits and negatives F through the day. This afternoon, wind will shift east at 5-15 mph. Continued snow showers through tonight will drop 3-6” in most locations with 8-12” near Cooke City by morning.
The mountains near Cooke City got 2-3 feet of snow equal to 2.5” of snow water equivalent (SWE) since Friday. Strong, gusty wind yesterday created consistent whiteout conditions and drifted snow into 1-4’ thick wind slabs at all elevations. This rapid, heavy loading event created dangerous avalanche conditions and large avalanches are likely today. Moderate wind and snowfall through today will continue to stress the snowpack and make large avalanches easy to trigger, especially on wind loaded slopes. Be cautious of smaller terrain, such as the steep edges of creek beds and gullies, where smaller slides are deadly because snow and debris will pile deep. Avoid ALL steep slopes and minimize time spent underneath them. Avalanche danger today is HIGH on wind loaded slopes and CONSIDERABLE on all other slopes.
The mountains south of Bozeman, near Big Sky, and near West Yellowstone got over a foot of snow equal to 1.5” of snow water equivalent (SWE) since Friday with 1” of that SWE since yesterday. Strong wind yesterday drifted snow into wind slabs 1-3’ thick that are easy to trigger today (video). These slabs are found near ridgelines and at all elevations on steep, convex rollovers and cross-loaded gullies. On non-wind loaded slopes, dry loose avalanches and slabs of new snow are possible to trigger. Avoid wind loaded slopes, and avoid all steep slopes if you see signs of instability like shooting cracks, collapsing, or fresh avalanches. Avalanche danger today is CONSIDERABLE on wind loaded slopes and MODERATE on all other slopes.
The Bridger Range saw the least of the storm, and since yesterday received 4” of new snow equal to .4” of SWE in the northern part of the range and a trace to 1” of snow at Bridger Bowl. I went to Fairy Lake yesterday where strong winds were drifting recent snow and growing 1-2’ thick slabs that were easy to trigger (video). We found lower density snow underneath hard wind slabs, which made them more unstable and slower to gain strength. Moderate wind and snowfall today keeps wind slabs on edge and easy to trigger. These slabs will gain strength with time, but assessing their stability is tricky today. They may appear glued on with an initial ski cut, and then come loose on the second or third turn. Avoid wind loaded slopes today. Avalanche danger is CONSIDERABLE on wind loaded slopes and MODERATE on all other slopes.
Upcoming Avalanche Education and Events
BOZEMAN
Feb. 28th, Know Before You Go avalanche awareness, 7:00 p.m. @ Procrastinator Theater, MSU
March 2nd and 3rd, SheJumps Companion Rescue Clinic, Info and Register HERE
March 2nd, Avalanche Awareness, 7-8:00 p.m., MAP Brewing Bozeman Split Fest
March 7th, Avalanche Awareness, 6-7:30 p.m. @ REI
DILLON
Feb. 24th and 25th, Snowmobile intro to avalanches w/ field course. More info: https://msuextension.org/conference/.
COOKE CITY
Every Friday and Saturday, Current Conditions Update and Avalanche Rescue, Friday 6:30-7:30 p.m. at The Soda Butte Lodge in February. Saturday anytime between 10-2 @ Round Lake.
Yesterday, a skier was caught and killed in an avalanche in the backcountry near Jackson Hole Mountain Resort (Article). This is the eight avalanche fatality in the U.S. this season. Current heavy snowfall and recent strong wind call for extra caution today.