Good Morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Wednesday, February 22nd at 6:45 a.m. Today’s advisory is sponsored by Excel Physical Therapy and Gallatin County Search and Rescue. This advisory does not apply to operating ski areas.
The southern mountains picked up 3-5” of snow yesterday morning. Between 4 and 6 a.m. today, 2-3” fell at Bridger Bowl and Big Sky. The gale force winds (89 mph at Lulu Pass) have subsided and are now blowing 20 mph out of the west to southwest with gusts of 30-40 mph. Skies are cloudy and mountain temperatures are in the low teens. Today, winds will shift northerly as scattered snow showers drop 3-5” of new snow by morning.
Yesterday morning a few inches of snow fell in the southern mountains (.3-.5” SWE). Four-day storm totals show a settled depth of 2’ of heavy, dense snow measuring 2.5-3” of SWE, but snowfall is only part of the weather story, wind is the other. Gale force winds swirled from many directions and left little terrain unaffected. Speeds measured 60-90 mph over 3 days, knocked down trees and built thick wind drifts at all elevations. Saying the last few days were windy is like saying the Sahara Desert is sunny. Eric and I rode into Lionhead and found many avalanches on wind-loaded slopes (photo). We investigated one that broke when a falling tree likely triggered the slope (video, photo). The slides were breaking a couple feet deep on a layer of facets that formed a few weeks ago. In some areas this weak layer is sitting on an ice crust. No matter, new snow and wind-loading created avalanches. Even though snowfall and wind have tapered off, people are still likely to trigger avalanches today and the danger is rated CONSIDERABLE on all slopes. Avalanches are the #1 sign that adjacent slopes are dangerous. Skiing or highmarking next to slides is asking for trouble (photo).
The northern Madison Range has gotten a few inches of snow this morning which will be blown into fresh wind drifts. The avalanche concern has less to do with loading and more to do with buried weak layers. A thin layer of weak, faceted snow is breaking clean 1.5-2’ deep in stability tests. We treat these results as a warning that avalanches are still possible. Both the buried weak layer and fresh wind slabs are creating a MODERATE danger on all slopes.
The Bridger and northern Gallatin Ranges have gotten a heavy dose of wind and little snow. Avalanche conditions are generally safe and slopes are unlikely to be triggered. The winds fed cornices at ridgelines and their growing size is a concern. These overhanging monsters weigh tons but can sometimes be broken off by the mere touch of a ski pole, so give them a wide berth. For today, the avalanche danger is rated LOW on all slopes.
Eric will issue the next advisory tomorrow morning by 7:30 a.m.
Less People, More Fatalities, a new article by Doug Chabot on avalanche fatality trends in Montana.
We rely on your field observations. Send us an email with simple weather and snowpack information along the lines of what you might share with your friends: How much new snow? Was the skiing/riding any good? Did you see any avalanches or signs of instability? Was snow blowing at the ridgelines? If you have snowpit or test data we'll take that too, but this core info is super helpful! Email us at mtavalanche@gmail.com or leave a message at 406-587-6984.
Beacon Training Park at Beall: Open and free to the public for avalanche beacon practice seven days a week from 9 a.m. to 8 p.m., southeast corner of Beall Park in Bozeman (photo).
COOKE CITY
Weekly rescue training and snowpack update, 6:30-7:30 p.m., Cooke City Super 8 on Friday, Lulu Pass Road for field location Saturday (Look for the yellow sign).
Bozeman
March 1, 1-hr Avalanche Awareness, 6-7p.m., REI Bozeman.
March 4, Pinhead Classic, Proceeds to benefit Friends of GNFAC. More info here.