Good morning. This is Mark Staples with the Gallatin National Forest Avalanche Advisory issued on Thursday, February 19, at 7:30 a.m. The Soda Butte Lodge in partnership with the Friends of the Avalanche Center sponsors today’s advisory. This advisory does not apply to operating ski areas.
This morning temperatures were in the upper 20s F and westerly winds were blowing 20 mph gusting 30 mph. Temperatures were a little cooler and winds were a little calmer near West Yellowstone and Cooke City. Today will have sunshine for much of the day with clouds building in the afternoon. Temperatures will climb into the 30s F but cold air from the north will move over the area today bringing colder temperatures for this weekend. Winds will continue blowing 20-30 mph mostly in the Bridger Range but ease this afternoon. An inch of snow could fall by Friday morning with more coming during the day.
Bridger Range Northern Madison Range
Northern Gallatin Range Cooke City
Yesterday the Bridger Bowl Ski Patrol triggered some 10 inch thick wind slabs. Skiers in the northern Bridger and northern Gallatin ranges observed winds transporting snow and forming fresh drifts and wind slabs in the typical spots under ridgelines and in steep gullies. In isolated places a thin weak layer may exists and is worth checking for. Do a quick stability test to make sure it’s not there. It’s only buried a foot or two deep, so this check should only take 5 minutes. Most slopes don’t have this weak layer and the snowpack is strong and stable as Doug found near Bridger Bowl (video) and Eric found near Mt Blackmore (video) on Monday. For today, the avalanche danger is rated MODERATE on wind-loaded slopes steeper than 35 degrees and LOW on all others.
Southern Madison Range Southern Gallatin Range
Lionhead Area near West Yellowstone
Just as in the northern mountains, wind slabs and drifts can be triggered today but these should be easy to see and avoid. A more difficult problem is a weak layer of surface hoar buried 1-2 feet deep. We have found this layer in Taylor Fork, Teepee Basin, and Lionhead (video). This layer mostly exists on slopes sheltered from the wind without many old snowmobile tracks. If you find a slope with great powder, there’s a good chance it has this buried weak layer and could produce an avalanche. For today with fresh wind slabs on some slopes and a buried weak layer on others, the avalanche danger is rated MODERATE on any slope steeper than 35 degrees and LOW on less steep slopes.
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.
AVALANCHE EDUCATION and EVENTS
Take a look at our Education Calendar for all classes being offered.
Companion Rescue Clinic, Bozeman, REI, 6-8 p.m., Friday, February 20 and 10 a.m.-2 p.m. on Saturday, February 21 (field location TBD). Pre-registration is required: www.rei.com/stores/bozeman.html
1-hour Avalanche Awareness, West Yellowstone, Holiday Inn, 7 p.m., Saturday, February 21.
Companion Rescue Course for Snowmobilers, Cottonwood Drainage, Crazy Mountains, Saturday, February 21, 9:30 a.m. – 2 p.m. Please RSVP to your club officers or to kathrynjbarker@fs.fed.us if you are interested in participating.
Snow Science and the Human Factor, Big Sky, location TBD, 6-8:00 p.m., Tuesday, February 24. The free event will feature a talk by Powder editor and MSU graduate John Stifter, multimedia presentations on the human factor in avalanche risk, a panel of experts from MSU’s Snow & Avalanche Lab and Gallatin National Forest Avalanche Center, as well as a Q & A session.