Avalanche: Yellow Jacket

D. Gluckman, AG

Salt Lake » Mill Creek Canyon » Yellow Jacket

Yellow Jacket Trees

8,800'

Northeast

Skier

Hard Slab

Persistent Weak Layer

Facets

3'

900'

At 9:20AM, while ascending Yellow Jacket Gulch towards Yellow Jacket Trees, our party of 2 remotely triggered a soft slab avalanche, which subsequently triggered 2 sympathetic avalanches. While in low-angle terrain on the north side of the Gulch, we heard an audible "whumpf" and could see the scrub oak ~25 feet in front of us shake just before the first crown formed upslope. We then observed the flow of debris from a sympathetic avalanche further up the ridge of the initial avalanche. Behind us, we observed the powder cloud of a third avalanche whose crown was on the opposite (northwest) side of the subridge. The three avalanches, in total, formed approximately 900' of crown throughout what could easily be chalked up to unassuming, treed and shrubby terrain.  We dug a pit in an adjacent meadow to the first sympathetic avalanche. We found a HS of 130cm with approximately 65cm of new snow. The new snow progressed linearly from F to 4F hard. The old snow was largely F hard and well faceted. We found an ECT-Moderate, Q1 failing on well developed facets at the old-new snow interface.