Good Morning. This is Mark Staples with the Gallatin National Forest Avalanche Advisory issued on Thursday, January 14, at 7:30 a.m. Sweet Pea's Nursery, in cooperation with the Friends of the Avalanche Center, sponsor today's advisory. This advisory does not apply to operating ski areas.
Early this morning it was snowing and 1-2 inches had accumulated in the mountains by 7 a.m. Unfortunately this fleeting storm will only lay down another ½ to 1 inch of additional snow. Temperatures were in the low 20's F and will rise into the upper 20's today under mostly cloudy skies. Light winds were blowing from the W and SW at 5-10 mph while stronger ridgetop winds in the Bridger Range were blowing about 20 mph. Today winds will continue at these speeds blowing from the W and slightly NW.
Last week stability assessments were easy. Avalanches occurred on many slopes and the snowpack produced noticeable collapsing and cracking. These were clear signs of an unstable snowpack. The situation has changed as the snowpack has adjusted to the weight of last week's snow and avalanche activity has diminished. Unfortunately the structure of the snowpack responsible for recent avalanches has not changed, and recent warm weather has not affected weak, faceted snow buried 2-3ft deep. To further complicate matters, sheltered slopes at or below treeline may contain a layer of buried surface hoar. The problem with surface hoar is that it forms on all slopes but only survives on a few. It has been found near West Yellowstone, Cooke City, and Big Sky. While many of these low elevation, sheltered slopes may seem safer than big alpine bowls they are not, and a regular observer near Cooke City experienced collapsing and cracking on these types of slopes yesterday.
On Tuesday near Mt. Blackmore my partner and I had little confidence in the snowpack and we dug multiple snowpits while approaching the slope we hoped to ski. Even though isolated columns required much force to break, we opted for a more conservative line and skied a slope less than 35 degrees. While riding near Lionhead Doug did not trust the snowpack either. Before crossing a small 30 degree slope, he stopped to dig a snowpit and evaluate stability. This low confidence in the snowpack is based on the existence of a persistent weak layer that has demonstrated the ability to produce avalanches. For this reason 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. Careful snowpack evaluation, cautious routefinding and conservative decision-making are essential for safe travel.
I 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.
Ski Movies/Fundraiser
Hans Saari Memorial Fund presents the UP THERE Film Fest Thursday and Friday, January 14-15 at the Emerson Cultural Center - Two Films, including Mike Marolt's Skiing Everest and Swift, Silent, Deep, the Story of the Jackson Hole Air Force will be shown. For more info go to www.hansfund.org
Avalanche Education
1. University of Montana/ Western, Room 311 Block Hall, Dillon, MT
One-hour Avalanche Awareness Class - Thursday, January 14th - 7pm to 8pm
2. University of Montana/ Western, Room 311 Block Hall, Dillon, MT
One-hour Avalanche Awareness Class - Friday, January 15th - 7pm to 8pm
3. Cooke City Fire Hall
One-hour Avalanche Awareness Class - Saturday, January 16th - 6pm to 7pm
4. 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
5. Bridger Bowl
AAI Level 1 Avalanche Course - Friday, January 22nd to Sunday, January 24th
www.americanavalancheinstitute.com
6. 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.
7. Billings
Avalanche Awareness and Rescue Class-Wednesday, January 27th, 6-9 pm at Beartooth Harley.
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. Holiday Inn, West Yellowstone
One-hour Avalanche Awareness Class - Saturday, January 30th - 7pm to 8pm