Avalanche: Silver Fork

Observer Name
GregS, NateC
Observation Date
Saturday, March 30, 2024
Avalanche Date
Saturday, March 30, 2024
Salt Lake » Big Cottonwood Canyon » Silver Fork
Location Name or Route
Brad's Line
Trigger: additional info
Unintentionally Triggered
Avalanche Type
Soft Slab
Avalanche Problem
New Snow
Our party of two had set out for the day to just get some vert and stay in relatively benign terrain. Our plan was to go up green's basin, ski into silver fork for a lap or two, then lap mat's basin, and ski out green's basin. We we not expecting much based on the warmth in the parking lot of Spruces. When we reached the top, there still was very little wind, but knowing that overnight there had been some, we pushed farther over to the south to the lower angle terrain.
I skied first down Brad's line from the top to the first set of trees. The skiing was awkward with a lot of weird density changes underfoot as we skied down. Both my partner and I noticed this and discussed it at tree line. But neither of us noticed any movement or instability coming down and didn't move much snow in our turns. Generally we were pleased with the cohesiveness of the snow after the first 6-700ft of skiing.
We moved through the trees as we started negotiating our exit to skin back up the shoulder. My partner moved right and I followed. We reconvened at a small opening and discussed the next pitch, even noting a plan if there was any movement.
I skied down noticing the density again in my first turn, made about 3 turns before I could hear him yelling "right!" and started moving hard right.
He first called because wet loose sluff was running more than expected and he didn't want it to catch me, but then it stepped down from the initial ~4" or so of storm snow to another 8" to the crust from earlier this week. He yelled "right" and "avalanche" as I continue right to the trees. I stopped and looked back to see bulk of the slope run past me and continue down into the trees another ~3-400ft. The slide total was about 100ft wide and ran a total of 5-600ft. It was not big enough to bury anyone, but it had enough momentum and speed to carry you into the trees below and create blunt trama.
I moved back to the left to get out from any hangfire above and my partner skied down to join me via the ridge.
We then moved out from under the slope and down to the skinner and skied out Silver Fork as conditions were not worth the continued risk for the day.
Overall, it was a surprising result, especially that it stepped down.
I had a good partner who was keeping eyes on me. As we have traveled extensively in the backcountry together, I knew instinctively what he was communicating when he called "right". I think we both lowered our guard a bit on the lower pitch after successfully navigating the top which I think we both had determined would be the more concerning slope.
One take away we both had was that radios would have made it even smoother - it would have been easier for him to communicate to me what was happening above and behind me on the radio rather than shouting. I had left mine behind earlier in the week. It will be just one more permanent part of the kit moving forward.