Merry Christmas! This is Mark Staples with the Gallatin National Forest Avalanche Advisory issued on Friday, December 25 at 7:30 a.m. Doug, Eric, and I wish all of you a Merry Christmas and Happy Holidays. Bridger Bowl, in cooperation with the Friends of the Avalanche Center, sponsor today's advisory. This advisory does not apply to operating ski areas.
Ho Ho Ho! Perhaps some powder hounds haven't been too naughty and just nice enough to get a trace of snow near Big Sky and one inch of snow near Cooke City. Cloudy skies this morning kept temperatures from getting too cold and were near 10 degrees F at 4 a.m. Winds have remained strong blowing from the NW at 15-30 mph. Today winds will continue from the NW and decrease slightly to 10-20 mph with temperatures climbing into the mid teens F. Mostly cloudy skies will produce some snow flurries with only a trace to 1 inch of additional snow accumulating by tomorrow morning.
The Gallatin and Madison Ranges, the Lionhead Area near West Yellowstone, the mountains outside Cooke City and the Washburn Range:
Wednesday's snowfall produced only 2-5 inches, but that load with strong winds added just enough stress to the snowpack to keep it near its breaking point. Experienced backcountry skiers in Beehive Basin found very scary conditions. They observed collapsing and cracking and triggered an avalanche on a 32 degree slope. These are all signs of instability not to be ignored. The Yellowstone Club Ski Patrol triggered several large avalanches on Wednesday that fractured on facets near the ground despite repeated blasting on previous days. Yesterday the Big Sky Ski Patrol also triggered an avalanche that fractured on facets near the ground. These avalanches indicate the fragile nature of the snowpack.
Since yesterday winds have not decreased much and continue blowing from the NW. Even though wind loaded slopes will be the most sensitive, any slope steeper than 30 degrees is capable of producing an avalanche. Today the snowpack is unstable, human triggered avalanches are probable, and the avalanche danger is rated CONSIDERABLE.
The Bridger Range:
Winds in the Bridger Range have been blowing stronger than in other mountain ranges and have left few slopes untouched. Good powder will be found only on the most sheltered slopes while others will be either scoured or loaded. Layers of faceted snow exist in the snowpack. They do not seem as weak as in other areas, but they are easy to find in a snowpit, and I do not trust them. Recently wind loaded slopes will fracture under the weight of a skier or rider producing an avalanche at least 1ft deep though it could easily break deeper on the buried facets. Today on wind loaded slopes the avalanche danger is rated CONSIDERABLE. Human triggered avalanches are possible on all other slopes where the avalanche danger is rated MODERATE.
Eric will issue the next advisory tomorrow morning at 7:30 a.m. If you get out in the backcountry give us a call or email with your observations. You can reach us at 587-6984 or email us at mtavalanche@gmail.com.
AVALANCHE EDUCATION
1. WEST YELLOWSTONE
Snowmobilers and Skiers: Saturday, January 2 from 12-5 pm at the Holiday Inn is avalanche lectures. Sunday, January 3 will be an all day field session for both skiers and snowmobilers. $30 suggested donation. No sign up required. http://www.mtavalanche.com/education/classes/snowmobilers
2. BOZEMAN
Level 1: 7-10 January, Montana Outdoor Science School is offering a Level 1 Avalanche Course. Instructors are Angela Patnode and Jay Pape. For more information, contact Montana Outdoor Science School at 406-582-0526.
3. BOZEMAN
Level 1: American Avalanche Institute is offering a Level 1 Avalanche Course January 22-24, 2010 at Bridger Bowl. Get more information and register at: www.americanavalancheinstitute.com
4. FOUR CORNERS
Rescue Lecture: On Tuesday, 26 January, the Gallatin Valley Snowmobile Association is having it annual Chili Feed at 6:30pm in the Groomer Shack. At 7:00 there's a free Avalanche Rescue Talk. http://www.mtavalanche.com/workshops/calendar
5. BOZEMAN
Basic Avalanche Workshop: The Friends of the Avalanche Center and MSU are offering a Basic Avalanche Awareness Class the evenings Wed, Thur, 27 & 28 January with a field day on Saturday, 30 January. $25 donation. No sign up required. http://www.mtavalanche.com/education/classes/basic