Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on the eve of Christmas eve, Tuesday, December 23, at 7:30 a.m. Today’s advisory is sponsored by Cooke City Bearclaw/Super 8 in partnership with the Friends of the Avalanche Center. This advisory does not apply to operating ski areas.
Snowfall distribution in the last 24 hours appears random. A trace to one inch fell in the Bridger Range, around Big Sky and West Yellowstone while 2-3 inches fell up Hyalite, Carrot Basin and Cooke City. Under partly cloudy skies the snowfall has ended, temperatures dropped to 10F and winds have calmed to 10-15 mph out of the W-SW. Today will be mostly sunny with light winds and mountain temperatures climbing to the upper 20s. No new snow is expected in the next 24 hours.
Gallatin Range Madison Range
Lionhead area near West Yellowstone Cooke City
We were scratching the belly of an Avalanche Warning the past few days, but there wasn’t enough snow to push us over the edge. The storms dropped 1.5 to 2 inches of snow water equivalency with strong winds. During the storm on Sunday Eric and I rode by braille on Buck Ridge and found the new snow wanting to slide on the old snow surface in our stability tests (small facets and/or surface hoar). Yesterday I toured into Beehive Basin and also found poor stability. On the trail, soon after leaving the car, we saw a small avalanche on a steep, wind-loaded creek bank that was triggered by a dog an hour earlier (photo). This was bulls-eye information that the snow was unstable. The spooky part of the day was that I was expecting lots of cracks and collapses, but got relatively little. This lack of warning could lure someone to believe the snow is more stable than it really is. Our snowpit and poor stability test further confirmed the hazard. Check out all our media over the last 48 hours: Buck Ridge video; Beehive Basin video; pictures of both.
The mountains from Bozeman to West Yellowstone and Cooke City got walloped with snow and have a very similar snowpack to what we found around Big Sky. The weakest layer in the snowpack is found directly under the new snow. I do not expect folks to trigger avalanches from afar, but I certainly expect folks to trigger them if they get into avalanche terrain. Given the weak snowpack and recent snow and wind the avalanche danger is rated CONSIDERABLE on all slopes today.
Bridger Range
The Bridger Range got the short end of the stick with only seven inches of snow since Saturday morning. The snowpack structure is similar to everywhere else, thin and weak, but was able to handle the incremental loading. Ridgetop winds are currently light and not moving much snow. The main concerns for triggering avalanches are two-fold: wind drifts near the ridgelines which are reported to be 18” thick, and a weak layer of facets and/or surface hoar directly underneath the new snow. For today the avalanche danger is rated MODERATE on all slopes.
I 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.
AVALANCHE EDUATION and EVENTS
Take a look at our Education Calendar for all our classes being offered.
Snowmobiler Rescue Course, Cooke City, December 27, 0800-1200. Register here: https://www.ticketriver.com/event/13721
1-hour Avalanche Awareness for Snowmobilers, West Yellowstone, 7 p.m., Saturday, January 3, Holiday Inn.
Companion Rescue Clinic, Bozeman, Fri eve and Sat field, January 9 and 10, REI. Register for the class here: www.rei.com/stores/bozeman.html
1-hour Avalanche Awareness for Snowmobilers, West Yellowstone, 7 p.m., Saturday, January 10, Holiday Inn.