Observation: Grizzly Gulch

Observation Date
2/17/2025
Observer Name
AAI Rec Level 2
Region
Salt Lake » Little Cottonwood Canyon » Grizzly Gulch
Location Name or Route
Grizzly Gulch
Weather
Sky
Overcast
Precipitation
Moderate Snowfall
Wind Direction
West
Wind Speed
Light
Snow Characteristics
New Snow Depth
10"
New Snow Density
Medium
Snow Surface Conditions
Powder
Red Flags
Red Flags
Recent Avalanches
Heavy Snowfall
Wind Loading
Collapsing
Poor Snowpack Structure
Red Flags Comments
One loud terrain-feature-sized collapse while post-holing into neighboring snowpit.
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Same
Problem #1 Comments
We investigated radiation recrystallization on a southwest-facing slope in upper Little Cottonwood. The undisturbed site was at 9,700' with a 24° slope facing 210° SSW. The snowpack was ~250 cm deep, with a dust/graupel layer 140 cm below the surface. Above this, a 2-3 cm melt-freeze crust contained ~1mm faceted grains. ECT tests showed no propagation within 30 taps, but a CT test resulted in a Sudden Collapse at 30 taps. A PST test indicated instability (PST 44/115cm END). The overlying slab was right-side up generally fist to 1-finger hard.
Comments
Thanks to Steven Eyberg for the photo.
Today's Observed Danger Rating
None
Tomorrows Estimated Danger Rating
None
Coordinates