Observation: Mill A

Observation Date
2/27/2019
Region
Salt Lake » Big Cottonwood Canyon » Mill A
Location Name or Route
Mill A Basin
Red Flags
Red Flags
Recent Avalanches
Wind Loading
Cracking
Collapsing
Avalanche Problem #1
Problem
Wind Drifted Snow
Problem #1 Comments
On Mt Raymond's shoulder to the south at 9800' saw the following.
Avalanche- Observed a small wind slab avalanche. 30'x6" ran 200 vert. crown just below cornice NE. not sure on date. Ski tracks in area from may be yesterday. Bed looked fresh and being actively wind deposited on. 1 larger chunk seen. Could be skier trigered natural from wind loading or cornice. Skier triggered guess would be yesterday, natural guess from this am or last night. Bad vis. hard to tell.
Micro wind slabalanche-I broke off a small 6' kiddie pool. 4"deep. same aspect elevation as above, just downridge.
There were other areas that would have slid imo if ridden.
Collapse- 1/2 mile downridge N facing Felt a collapse. 100' below the ridge below a rock band.
Active loading-Moderate to strong winds, light snow transport. light snow (1/8" an hour) starting at 10ish. still snowing as we left @1. Sleet at s turn driving down @1.
Going to be harder to see the wind slabs with a little bit of fresh snow. fresh snow may provide more ammo for wind slabs as well as a weak layer/density change.
Comments
tour was 8:30-1 Maxfield basin to mill a basin. 9900-7000
Experienced a collapse with shooting cracks triggered as my partner approached/ tucked behind some rocks with me. barely detectable crack 8' ahead. there is rough guess 4-8 inches of 4 finger snow on top of 3-4" of 1 finger snow. I think the collapse was below the layer with 1 finger snow that is a base for skis but not sure...
I put considerable for what we observed above 9500. I would think avalanches small and manageable and in localized areas and therefore moderate might be more appropriate, but I am suspicious that the wind slabs may break behind riders and things felt a bit touchy to me.
We toured in a area where wind slabs were likely, which also probably flavors my rating. (lee side of wind, big fetch, high up with no mountains blocking flow)
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
None