Observation Date
3/21/2019
Observer Name
Gagne/Frey
Region
Salt Lake » Little Cottonwood Canyon » White Pine
Location Name or Route
White Pine
Weather
Sky
Obscured
Precipitation
Moderate Snowfall
Wind Direction
South
Wind Speed
Moderate
Weather Comments
Very poor visibility in the alpine. Periods of heavier snowfall in the morning, with gusty winds from the south (weather stations were reporting consistently from the southeast).
Snow Characteristics
New Snow Depth
4"
New Snow Density
Medium
Snow Surface Conditions
Powder
Rain-Rime Crust
Damp
Snow Characteristics Comments
10-15 cms new storm snow, with some dense drifts that were sensitive. Storm snow is quite damp below 8500'. The snow came in warm enough that it has bonded well to the old surfaces, even in upper elevations where the existing snow surface was dry.
Red Flags
Red Flags
Wind Loading
Cracking
Collapsing
Red Flags Comments
We got several collapses today. These were on upper elevation northerly slopes where the old snow surface had remained dry and soft, with some weakening due to faceting. Recent winds had created a 10-15 cm hard wind slab on top of this weak snow, with new storm snow and wind-blown snow on top. The collapses were likely from the weaker snow underneath these recent wind-loading events.
Also quite a bit of cracking in new storm snow, especially in areas that were wind drifted.
Avalanche Problem #1
Problem
Wind Drifted Snow
Trend
Same
Problem #1 Comments
Southerly winds were creating shallow pockets of fresh, sensitive wind drifts in the mid and upper elevations, generally above 9000'. Most of these drifts were shallow (< 10 cms), but some were up to 45 cms thick. The widest wind slab I could get to propagate was 15'. With continued snow and winds in the forecast, this should remain an issue for Friday.
Comments
Overall stable conditions, but pockets of wind drifted snow above 9000' remains the biggest avalanche concern for Friday. I was able to ski cut some steeper, northerly slopes at the upper elevations, and couldn't get any sluffs to move, but I wouldn't be surprised to hear others were able to get sluffing in the storm snow.
Video describing structure where we were finding collapsing.
Video
Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
Moderate
