Good morning. This is Mark Staples with the Gallatin National Forest Avalanche Advisory issued on Saturday, February 26, at 7:30 a.m. The Yellowstone Club Community Foundation in cooperation with the Friends of the Avalanche Center, sponsors today’s advisory. This advisory does not apply to operating ski areas.
No snow fell in the last 24 hours. This morning temperatures dropped into the negative single digits F, and in some valley locations temperatures dropped into the negative teens. Winds were mostly calm yesterday and last night but increased this morning to 20-40 mph from the W and SW. Today winds will continue and maybe increase a bit more. Fortunately more sunshine is expected and high temperatures in the upper teens F. Clouds may return Sunday and more snowfall should come early next week.
The Bridger, Madison and Gallatin Ranges, the Lionhead area near West Yellowstone, the mountains around Cooke City and the Washburn Range:
Today’s ridgetop winds combined with plentiful soft snow will form fresh wind slabs which will be the main avalanche problem. A related problem is the growth of cornices. It’s hard to know when they have reached their breaking point, but when they do, falling cornices make good triggers for avalanches.
Eric went to Buck Ridge and MacAtee Basin yesterday near Big Sky. He did not observe any recent avalanche activity and none of his stability tests propagated fractures, a good sign. See his snowpits posted here. Just north of Big Sky, a skier found similar results in his stability tests and only observed some loose snow sluffs. Further away near Cooke City, a skier didn’t find any major concerns in the bonding between new and old snow, but he did get small soft slab to move on a test slope. Deeper layers in the snowpack are generally well bonded, but a fresh wind slab can fracture and avalanche within the surface layers of snow.
Assessing unstable avalanche conditions can be easy. Assessing stable conditions can be more difficult and requires evidence similar to a criminal trial where a conviction requires proof beyond a reasonable doubt. For a conclusion of stability, the proof must be a combination of: NO recent avalanche activity, NO collapsing or cracking, and NO “bad” results in multiple stability tests. Lastly we need to ask “Is the weather contributing to instability?” Recent snowfall occurred over many days (versus overnight) and the snowpack has been able to adjust to this loading. The main issue is wind loading near ridgetops, but this avalanche problem is easily avoided.
For today, the avalanche danger is rated MODERATE on all wind loaded slopes and MODERATE all slopes steeper than 35 degrees. On less steep slopes unaffected by wind, the avalanche danger is LOW.
Eric 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.
UPCOMING EVENTS
3rd Annual Montana Ale Works Fundraiser
Tuesday, March 1 at 6:00 p.m. in the Railcar at Ale Works in Bozeman
Cost: $25 to benefit the Friends of the Avalanche Center
Details: Chef Roth at Montana Ale Works is creating tapas style servings that will be paired with select beer from Lone Peak Brewery. More information HERE.
Pinhead Classic
The 30th Annual Pinhead Classic on is Saturday, March 5th. “Gangsters and Flappers” is this year’s costume theme, so come dressed up to race, socialize and wind great prizes. Registration is $30 but get you all sorts of cool stuff. All proceeds benefit the Friends of the Avalanche Center. Check out the website http://pinheadclassic.com for details.
OTHER NEWS
New Snowpits Page
In response to our survey we added a new page to the website with images of our snowpit profiles. This page is under the Resources/Other Info tab at www.mtavalanche.com/snowpits
Backcountry Skier Survey – Researchers at Alaska Pacific University are studying decision making in backcountry skiers and would like to get information from you. If interested in this 10-15 minute survey, go to this website: https://www.surveymonkey.com/s/SE_AK_Backcountry_Skiing_Research