Observation: 10420

Observation Date
3/7/2019
Observer Name
Bruce Tremper
Region
Salt Lake » Big Cottonwood Canyon » 10420
Location Name or Route
Peak 10,420
Weather
Sky
Broken
Wind Direction
Southwest
Wind Speed
Light
Weather Comments
Just a quick trip up Peak 10,420 from Guardsman's Pass trailhead just for exercise. Weather was extremely variable with waves of alternating precipitation and clearing but winds remained fairly light.
Snow Characteristics
New Snow Depth
8"
New Snow Density
High
Snow Surface Conditions
Dense Loose
Damp
Snow Characteristics Comments
New snow was quite dense--mostly graupel--like most of the storms this past month or so and it was slabby, meaning that you would punch through the dense surface snow into the lower density snow from before the storm. Below about 9,000' the snow was damp because of the high freezing levels from the past storm.
Red Flags
Red Flags
Heavy Snowfall
Wind Loading
Poor Snowpack Structure
Red Flags Comments
As I noted several days ago in White Pine, the low density surface snow on the northerly aspects concerned me because a warm, wet windy storm was about to be deposited on top of it. And today, everything on upper elevation shady slopes had an obvious, slabby feel. In several quick column tests it was shearing off on the snow surface from before this latest round of snow from light to medium taps about 30-40 cm deep. The slabs were stubborn, though, and I jumped on several wind loaded test slopes on the way up the northwest ridge and did not get any collapsing, cracking or slabs breaking out. Obviously I did not jump on any of the steeper, higher consequence slopes and gave the monster cornices a wide berth. The new snow is so dense and warm that it's probably healing up quite fast. When we skied down on the northwest graded trees, we stayed on gentler terrain because I didn't quite trust the slabby snow. I was surprised not to see any avalanches or be able to get any test slopes to respond, but from reading the other obs from today, it looks like several others found them. With the colder temperatures and lower density snow forecast for Friday-Saturday, I'm guessing that most avalanche activity will be within the new snow but I also wouldn't be surprised to see isolated slides breaking down deeper to the layer that was active recently.
Comments
A couple of photos:
1) The obligatory cabin wind loading shot from Alta a couple days ago.
2) From today, heading up the ridge staying well back from the edge of cornices with high consequence slopes below.
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
Considerable
Coordinates