Northern Gallatin

"We triggered 3 significant persistent slabs with explosives on the south face, all in areas that had been rapidly loaded by last night’s winds.  Castro’s shoulder, Upper Rodeo and Jailbait (HV) all succumbed to the load and failed 3-6’ deep on the ice crust 30-60 cm off the ground and showed impressive propagation.  One significant new snow slide in Lenin failed 4-5’ deep just involving snow that had been deposited since this storm began." - BSSP

From an email:

"Skied from Bracket creek to the east facing glades below Ross Peak. At lower elevations very thin snowpack. As we got higher, snow had been significantly wind effected. Experienced several shooting cracks. At 8000 ft, snow was still only 50-75cm deep with variable wind slab. Did not dig a full pit, but hand shear tests showed the wind slab was very poorly bonded to the facets beneath. Winds were swirling and increased from calm to strong throughout the day. Blowing snow mostly filled in our tracks within about 30 mins."

From an email:

"Beauty of a day up in Hyalite so long as you didn't mind the wind. The SW/W winds were cranking and clearly transporting snow all day at ridgetop (photo attached). Above 7500' we consistently found ~20cm of new snow from the storm earlier in the week on on top of a thin soft slab over small (but well developed) near surface facets. - A quick pit at 8900' on a protected 30 degree East aspect yielded no obvious slab and no propagation in tests but did show fractures along the new snow/old snow boundary and consistent deeper collapses in the buried crust-facet-sandwich. - We did notice a few recent natural avalanches on wind loaded north aspects in aprons below large cliffs and underneath large cornices (D0.5 - D1, max depth 1m, max width 30m) but these seemed to mostly be small soft storm slabs. - One recent crown near the top of the Mummy (30cm deep) looked to have run naturally on an old crust layer (photo attached) - We avoided slopes greater than 35 degrees and wind-loaded open slopes today and experienced no cracking, collapsing or avalanching where we travelled. - The next front rolled in rather quickly at 3pm with S2+ snowfall and ripping winds throughout the valley."

@carter.olson, "I witnessed three snowmobilers trigger and get caught in an avalanche at second Yellowmule (Buck Ridge) at 12:40PM today. The lead snowmobiler triggered the avalanche while descending from his high mark with the other two snowmobilers below him. The lead snowmobiler was able to run out the avalanche to a degree and made it to the edge of the runout at the bottom. The other two snowmobilers were pointed uphill when the avalanche was triggered and shot into the trees when attempting to outrun the avalanche. The female was buried to her torso and the male was buried to his waist. Both sleds were buried about three feet under the debris. The Avalanche propagated about 1500ft wide. Luckily everyone involved was not harmed, just a broken a arm on one of the buried sleds.
Luckily I was able to jump into action, yelling “Avalanche, Avalanche, Avalanche” grabbing everyone in my group’s attention. Then I told everyone to get their beacons out and put them to search and get to where we last saw the snowmobilers. On our way to the last point of sight of the snowmobilers, they all screamed out they were ok."

This slide was triggered by Bridger Bowl ski patrol during control work on Saturday (1/4/2020) on "The Drain". This is a heavily wind loaded slope on the south end of the ski area adjacent to the backcountry (Saddle Peak). It shows deeply buried persistent weak layers from early October and November were pushed to a breaking point by the recent snow and wind.

From an email:

"Also observed a recent slide on the northwest face of elephant, at about 9000 feet, in the second elephant glade along the blackmore trail. Wind pocket looked to be triggered by a skier on their way out, maybe 30 feet wide, ran for a 80 feet. Looks like they stayed high, just below a rock band on their exit and cut the wind slab."