Good morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Advisory issued on Thursday, February 25, at 6:45 AM. Today’s advisory is sponsored by Grizzly Outfitters in partnership with the Friends of the Avalanche Center. This advisory does not apply to operating ski areas.
This morning, skies are partly cloudy with mountain temperatures in the high teens to low 20s F. Winds overnight have been westerly at 5-15 mph with gusts in the 20s. Today will be sunny with temperatures in the high 20s to low 30s F and wind out of the west at 15-20 mph. This mild, dry weather pattern will persist through Friday and there is a chance for snow Saturday morning.
Southern Madison Range Southern Gallatin Range
Lionhead area near West Yellowstone Cooke City
The mountains in the southern half of our advisory area have a layer of weak surface hoar buried 1-3 feet deep. Avalanches on this layer were triggered by skiers and snowmobilers last weekend near Cooke City and West Yellowstone. Doug investigated one of these slides during his visit to Cooke City on Monday (video, photo), and our photo page is stacked with evidence of this instability.
I toured near Hebgen Lake yesterday and found buried surface hoar in two of three pits that I dug (video). My partner and I found stable test results, but Karl Birkeland found unstable results at Bacon Rind a couple days earlier. Karl provided a great discussion of this layer’s distribution and instability in his video. Avalanches on this layer are less likely than they were last weekend and there are fewer signs of instability. However, surface hoar is a persistent weak layer that can cause avalanches for weeks after it is buried. It does not exist on every slope, but I would avoid steep slopes where it does exist. It is worthwhile to dig a few feet down and look for this layer. It is visible as a grey stripe in the snowpit wall (photo). If you don’t find it, dig in another spot to confirm it is not there.
Buried surface hoar makes it possible to trigger an avalanche today, so the danger is rated MODERATE on all slopes.
Bridger Range Northern Madison Range Northern Gallatin Range
The mountains in the northern half of our advisory area have a mostly stable snowpack. Some slopes have weak snow at the ground, but a lack of recent snow has allowed this poor snowpack structure to stabilize. Avalanches are unlikely, but not impossible. Dig a quick snowpit, only expose one person at a time to avalanche terrain, and carry rescue gear. Maintain good travel habits now in order to minimize the consequences of an avalanche, and to make safe travel second nature when the danger increases. For today, the avalanche danger is rated LOW.
I will issue the next advisory tomorrow morning by 7:30 a.m. If you have any snowpack or avalanche observations to share, drop us a line at mtavalanche@gmail.com or leave a message at 587-6984.
EVENTS and AVALANCHE EDUCATION
A complete calendar of classes can be found HERE.
Bozeman: Wednesday, March 9, 6-7 p.m. 1-hr Avalanche Awareness, REI.