Good morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Monday, March 7, at 7:00 AM. Today’s advisory is sponsored by Community Food Co-op and Yellowstone Ski Tours. This advisory does not apply to operating ski areas.
Yesterday’s fast moving storm dropped 4-5 inches of snow in the mountains around Bozeman and Big Sky. The mountains near West Yellowstone picked up 6-8 inches while Cooke City received 3-4 inches. This morning, skies are mostly clear as a ridge of high pressure builds over the area. Limited cloud cover has allowed temps to drop into the mid-teens to low 20s F and winds are blowing 10-20 mph out W-NW. Today, skies will be mostly clear and temps will warm into the upper 20s F. Winds will remain light to moderate out of the W-NW. The next chance for snow looks to be tomorrow night into Wednesday.
Southern Madison Range Southern Gallatin Range
Lionhead area near West Yellowstone Cooke City
Snow totals in the southern ranges were a bit spread out. Madison Plateau Snotel site near West Yellowstone topped the charts with .8 inches of SWE while Fisher Creek Snotel site near Cooke City recorded .3 inches of SWE. Despite the difference, both areas received enough snow to put the snowpack on edge.
The main concern today will be avalanches failing in the top 1-3 feet of the snowpack. Buried surface hoar is the primary layer of concern (video, video), but a facet-crust combination in the upper portion of the pack may also be problematic. Over the past few days, Alex has been in Cooke City and observed a few natural avalanches. One occurred on the Fin south of town (photo), while the other took place on Scotch Bonnet near Lulu Pass. Both slides broke 1-2 feet deep an appeared to be the result of heavy wind loading. These slides are obvious clues there are layers in the snowpack capable of propagating a fracture.
Today, new and windblown snow will be adding stress to buried weak layers. Digging a quick pit to evaluate the snowpack structure is always a good insurance policy before committing to steeper terrain.
Avalanche conditions won’t be hair trigger today, but giving the current set up human triggered avalanches remain possible and the avalanche danger is rated MODERATE on all slopes.
Bridger Range Northern Madison Range
Northern Gallatin Range
The northern ranges received a well needed touch up. Both Big Sky and Bridger Bowl recorded 4-5 inches of new snow totaling .4-.5 inches of SWE. Giving the generally strong and stable snowpack in these areas, this load won’t change avalanche conditions too much.
While the new snow will be well bonded to the firm old snow surface, areas of unstable snow could be encountered in steep, wind loaded terrain. Upper elevation slopes leeward to westerly winds will be the most susceptible to wind loading. I don’t expect fresh wind slabs to be exceptionally large, but they will be something you’ll want to avoid, especially in steep-high consequence terrain. Outside of wind loaded slopes, generally safe avalanche conditions exist.
Today, human triggered avalanches are possible on wind loaded slopes steeper than 35 degrees which have a MODERATE avalanche danger. All other slopes have a LOW avalanche danger.
Doug 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.