Good Morning. This is Mark Staples with the Gallatin National Forest Avalanche Advisory issued on Saturday, January 23, at 7:30 a.m. Bridger Bowl, in cooperation with the Friends of the Avalanche Center, sponsor today's advisory. This advisory does not apply to operating ski areas.
In the past 24 hours the mountains near West Yellowstone and Cooke City received 7-10 inches of snow. Big Sky and the Bridger Range received 4-6 inches, and the northern Gallatin Range got only 2. Snow was falling this morning and most areas will receive an additional 3-6 inches though I'd keep an eye on the Bridger Range where a bit more is possible.
An area of low pressure has moved east and pulled cold air down into the northern part of the advisory area with single digit temperatures this morning in the Bridger Range while other areas have temperatures in the teens F. Yesterday easterly winds slowly shifted to the south before blowing from the west this morning at 10-20 mph. Winds may increase slightly this afternoon as they continue dancing around the compass moving to the northwest. With cold air descending into the area, temperatures will only climb in to the teens to low 20s F today.
The Madison Range, the southern Gallatin Range, and the Lionhead area near West Yellowstone:
With new snow and winds natural and human triggered avalanches containing fresh wind slabs are likely near ridgetops or other terrain features with wind drifted snow. If these wind slabs were the only avalanche concern, backcountry travel would be easy. The problem is that layers of weak faceted snow exist several feet deep on all aspects and elevations. Prior to this storm these layers displayed obvious signs of instability such as collapsing and cracking as well as producing very low scores in stability tests. Avalanches breaking on these layers will not be as widespread as avalanches confined to fresh wind slabs but will be much larger and more deadly.
Today the avalanche danger is HIGH on wind loaded slopes. Slopes without wind-blown snow have a CONSIDERABLE avalanche danger.
The Bridger and northern Gallatin Ranges, the mountains around Cooke City and the Washburn Range:
The snowpack near Bozeman and Cooke City is not as weak as it is in other areas, and most avalanche activity will be confined to fresh wind slabs. I would not bet my life on this fact because the existence of faceted snow deeper in the snowpack means much larger avalanches are possible. This faceted snow has gained some strength but has not gone away. Remain wary of every slope until digging several quick snowpits and assessing the sensitivity of these facets. Today, on wind loaded slopes the avalanche danger is rated CONSIDERABLE. On non wind loaded slopes, human triggered avalanches are definitely 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
Education Calendar
1. 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.
2. Billings
Avalanche Awareness and Rescue Class-Wednesday, January 27th, 6-9 pm at Beartooth Harley.
3. 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
4. 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
5. West Yellowstone, Holiday Inn
One-hour Avalanche Awareness Class - Saturday, January 30th - 7pm to 8pm
