Observation: Cottonwood Canyons

Observation Date
4/6/2021
Observer Name
Greg Gagne
Region
Salt Lake » Cottonwood Canyons
Location Name or Route
Upper Big and Little Cottonwood Canyons
Weather
Sky
Obscured
Precipitation
Moderate Snowfall
Wind Direction
West
Wind Speed
Moderate
Weather Comments
Moderate to strong gusts from the west along exposed ridges, with some wind-drifting down off of ridges and channeling around terrain features leaving drifts on almost any aspect.
Snow Characteristics
New Snow Depth
12"
New Snow Density
Medium
Snow Surface Conditions
Powder
Wind Crust
Snow Characteristics Comments
Upper Little Cottonwood and Brighton backcountry fared well with this sleeper storm with 30 cms (12") settled snow above 9,500'. Some drifts were up to 60 cms (2')
New snow bonded well to the old snow surface and the only instabilities I could find were some density changes within the storm snow as well as some sensitive storm snow during periods of high PI. As is the case - especially in the spring - these instabilities rapidly settled out and by 11 am I could not find any instabilities. Wind drifts were the deepest right along ridge lines, and only shallow pockets once you got off of exposed ridges. Any fresh wind drifts were unresponsive to ski cuts, although I think it is possible there may still be some lingering drifts in the upper elevations that are reactive on Wednesday morning.
Red Flags
Red Flags Comments
Really no red flags - a nice surprise with greater-than-forecasted amounts of storm snow as well as fresh wind drifts, but a "typical" spring storm that quickly settled out and stabilized.
Comments
The primary avalanche concern for Wednesday will be warming of the new snow, although it may not be quite that touchy as it is rather dense and possibly already experienced some warming on Tuesday afternoon. The old snow surface was frozen solidly (10-15 cms thick) with damp grains underneath the crust, so any avalanche activity on Wednesday should only be wet loose avalanches that at most step down to the old snow surface. It is worth watching winds overnight and into Wednesday morning as fresh wind drifts - especially on north and east aspects - could also be a concern for Wednesday.
Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
Moderate