Avalanche: Flagstaff Gully

Observer Name
John Easterling
Observation Date
Saturday, April 22, 2023
Avalanche Date
Saturday, April 22, 2023
Salt Lake » Little Cottonwood Canyon » Flagstaff Gully
Location Name or Route
Flagstaff Face / Flagstaff Ridge
Avalanche Type
Soft Slab
Avalanche Problem
Wind Drifted Snow
After skinning up Flagstaff Ridge and skiing two runs to the Northeast off the summit of Flagstaff Mountain proper, we skied down the South side back to our truck.
When my partner made the first turn on Flagstaff Face he kicked off an avalanche. The visibility was terrible so it’s hard to say for sure, but I’d guesstimate 100’ wide and 12” deep. The debris looked to go down towards Flagstaff gully but I have no idea how far it went. My partner was able to keep his speed and ride off the slab skiers-left towards Emma #1. He got out unscathed.
We decided that what just happened was pretty damn scary and that we should pick our way back down along the skinner on Flagstaff Ridge to the lower angle terrain. I failed to point out how big the cornice along Flagstaff Ridge had become and the poor visibility made it impossible to see. My partner turned too close to the edge and fell about 10’ off the cornice onto the slope below. That slope was a similar aspect and angle as the upper section of Flagstaff Face and not surprisingly it ripped out as well. He was carried down towards Flagstaff Gully.
I hopped off the cornice onto the bed surface and skied behind him trying to keep him in view as the slide dragged him down towards the gully. He was thankfully on his toe edge (snowboarder) and was able to grab at the bed and direct himself towards a clump of small trees, then grab on to a tree and stop himself as the avalanche went past him. I'd estimate the second avalanche was a similar size, but lack of visibility and abundance of adrenaline made it hard to gauge.
From there we skied the bed surface down and eventually cut hard skiers right back onto the ridge once the angle lessened and the cornices abated. We followed the skinner home. Egos and feelings were the only things injured, thankfully.
Both slides failed on the old, brown sun crust. I'm not sure if it was just the crust, or if they were also wind loaded from Flagstaff Ridge.
We had checked the UAC avalanche report (moderate: wind, new snow and sun if it poked out) and had discussed our plan and both agreed that avalanche concerns were minimal. Turns out moderate danger ≠ low danger and low danger ≠ no danger.
The lack of visibility was a major contributor to the second, more serious avalanche.
Seeing no issues on the North side, we felt good on the south side. But clearly South was behaving differently than North. Also, since we'd been skiing all morning and hadn't seen any action, we didn't feel the need to slope cut Flagstaff Face. Had this been our first run, we might have cut it and things might have gone differently.
Overconfidence in familiar terrain definitely contributed to our hubris.