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Observation: 10420

Observation Date
1/14/2020
Observer Name
Greg Gagne
Region
Salt Lake » Big Cottonwood Canyon » 10420
Location Name or Route
10420'
Weather
Sky
Overcast
Wind Direction
Southwest
Wind Speed
Moderate
Weather Comments
Occasional strong gusts.
Snow Characteristics
Snow Surface Conditions
Powder
Dense Loose
Wind Crust
Snow Characteristics Comments
Who invited the wind to our powder party? Still decent ski conditions out of wind-affected terrain at the mid-elevations. In wind-affected terrain, pencil-hard wind slabs generally 10-30 cms (4-12") thick with some up to 45 cms (18") thick.
Red Flags
Red Flags
Recent Avalanches
Heavy Snowfall
Wind Loading
Cracking
Poor Snowpack Structure
Avalanche Problem #1
Problem
Wind Drifted Snow
Trend
Same
Problem #1 Comments
Wind drifts today were quite stubborn to initiate. My biggest concern is that the drifts were sitting on top of lower-density snow, as shown below
The stout wind slabs may allow someone to get well out onto a slope before fracturing.
Avalanche Problem #2
Problem
Persistent Weak Layer
Trend
Same
Problem #2 Comments
Existing structure of (1) facets/crusts on southerly aspects and (2) weak snow in thinner snowpack areas on northerly aspects remains a concern given the wind and significant water amounts. Stability tests today were showing these weak layers unreactive.
Comments
Winds were the issue today! Wind affect along exposed ridges and open bowls, and even down into mid-elevation terrain. The only reactivity I could get were fresh cornices, but the wind slabs were very hard (pencil-hard) and unreactive. My only concern is these drifts are now sitting on top of lower-density snow (strong-over-weak) and it may allow a rider to get well out onto a slope before avalanching.
Dug 3 different pits on southerly aspects, and 1 pit on a northerly aspect, all between 9-10k' and all were ECTN, failing within the top 50 cms within the recent storm snow.
I left the mountains before snowfall began, but i would think the snowfall Tuesday afternoon and evening will greatly improve riding conditions for Wednesday, especially on lower-angled terrain.
Photos showing:
- Etching of the snow surface from southwesterly winds
- Scouring of windward aspects
- Winds at mid to low elevations in Big Cottonwood Canyon
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
Considerable