Good Morning. This is Mark Staples with the Gallatin National Forest Avalanche Advisory issued on Saturday, January 16, at 7:30 a.m. The Yellowstone Club, in cooperation with the Friends of the Avalanche Center, sponsor today's advisory. This advisory does not apply to operating ski areas.
This morning temperatures were in the mid-high 20's F except in the mountains near West Yellowstone where they were in the teens F. Winds increased overnight and this morning were blowing in the 30's and 40's from the W and SW Today will start mostly sunny with clouds increasing this afternoon. Temperatures will rise to near 32 degrees F and winds will blow 20-30 mph from the WSW.
The Madison Range, and the Lionhead area near West Yellowstone:
The weakest snow in the advisory area exists in the mountains near Big Sky and West Yellowstone. Yesterday near Big Sky skiers triggered two avalanches but were not caught or injured. One slide likely involved a fresh wind slab about 12 inches thick while the other probably broke on buried facets about 3ft deep. The existence of these buried facets and yesterday's avalanche activity keeps my confidence in the snowpack very low. Do not trust the snowpack and give every slope a thorough stability assessment. A similar situation existed on this same weekend last year. The snowpack had become less sensitive and avalanche activity had decreased, yet three avalanche fatalities occurred on the same day in three separate avalanches. Today human triggered avalanches are probable on slopes steeper than 35 degrees where the avalanche danger is rated CONSIDERABLE. Less steep slopes have a MODERATE avalanche danger.
The Bridger and Gallatin Ranges, the mountains around Cooke City and the Washburn Range:
In the mountains near Bozeman and Cooke City the snowpack is slightly stronger. Doug and Eric covered many miles in the mountains north of Cooke City documenting avalanche activity that occurred over a week ago. Their stability tests indicated strengthening of the snowpack since then. In many areas similar conditions can be found, but some slopes remain weak as a pair of skiers found on the west side of the Bridger Range. Additionally some slopes contain wind slabs that may easily slide. Yesterday the Bridger Bowl Ski Patrol triggered a few slides of recently wind deposited snow up to 16 inches deep. Warm temperatures will help these wind slabs bond to underlying snow but they can still fracture under the weight of a skier or rider. Today many slopes will support the weight of a skier or rider but some will not. For this reason human triggered avalanches remain possible and 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. Cooke City Fire Hall
One-hour Avalanche Awareness Class - Saturday, January 16th - 6pm to 7pm
2. West Yellowstone, Holiday Inn
One-hour Avalanche Awareness Class - Saturday, January 16th - 7pm-8pm
3. Bozeman
MMA Teen Avalanche Class: Lecture Thursday, January 21st & Field Session Saturday, January 23rd. To sign up or get more information, call Erin Taylor Montana Mountaineering Associations at 522-0659
4. Bridger Bowl
AAI Level 1 Avalanche Course - Friday, January 22nd to Sunday, January 24th
www.americanavalancheinstitute.com
5. Four Corners Groomer Shack
RESCUE LECTURE: Tuesday, January 26th 7pm. The Gallatin Valley Snowmobile Association is having it annual Chili Feed at 6:30pm in the Groomer Shack at 4 corners.
6. Billings
Avalanche Awareness and Rescue Class-Wednesday, January 27th, 6-9 pm at Beartooth Harley.
7. Big Sky
Moonlight Basin Avalanche Course: Join Moonlight Basin for a comprehensive, two-day and one evening avalanche awareness class. Thursday, Jan 28th 5-9:30pm and Friday and Saturday, Jan 29&30 8am-4pm. Contact: events@moonlightbasin.com or 406-993-6026
8. Bozeman
BASIC AVALANCHE WORKSHOP: The Friends of the Avalanche Center and ASMSU Outdoor Rec 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
9. West Yellowstone, Holiday Inn
One-hour Avalanche Awareness Class - Saturday, January 30th - 7pm to 8pm