Observation: West Bowl

Observation Date
12/21/2015
Observer Name
Glew
Region
Salt Lake » Big Cottonwood Canyon » Silver Fork » West Bowl
Location Name or Route
Silver Fork
Weather
Sky
Obscured
Precipitation
Moderate Snowfall
Wind Direction
West
Wind Speed
Strong
Weather Comments
Blustery day, but not as windy as others reported on say the PC ridge line. We departed Alta at 9am back at 420pm and there was about 3 inches of light new snow on the car. However it felt like we were getting a lot more snow than we found on the car spending most of our day in the leeward aspects.
Snow Characteristics
New Snow Depth
3"
New Snow Density
Low
Snow Surface Conditions
Powder
Snow Characteristics Comments

Travel was in Grizzly, Davenport hill, West Bowl, and Emmas.

Winds were blasting mostly out of the W/SW.

We did get a few small soft slabs failing on the rain/rime crust about 8-12 inches deep. These slides traveled fast and far if the slope had a steeper pitch. Cracking was going down to this layer. No collapses noted.

I dug a pit on the southerly facing terrain around 10,000 ft and got a CT20 Q2 on facets below a sun crust about a foot from the ground. I dug another pit near the top of West Bowl in NE facing terrain. I got a CT18 Q2. There was about 8 inches of damp facets from the ground up, then 2 inches of dry facets where the failure occurred. The failure did not have much energy, but I ran into an Avy II course who dug nearby and got significant results on ECT's. Basically what I saw in the more suspect E and N facing terrain we traveled in is mostly unconsolidated snow sitting on top of facets. Once the snow pack gets more of a load its going to be suspect, especially on E,N,W facing terrain. I would expect the southerly facing terrain to potentially fail near the ground on the facets with enough wind and snow.

Another thing to note is that the rain/rime crust has a bunch of spacial variability. I did not really feel it poking around West Bowl. However in other places like the Cabin Run on Davenport hill it was pronounced. Upon our exit today the rain/rime event was burried under about 12 inches of snow. It was reactive in hand pits and ski cuts.

Red Flags
Red Flags
Recent Avalanches
Heavy Snowfall
Wind Loading
Cracking
Poor Snowpack Structure
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
High