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Observation: Brighton Perimeter

Observation Date
12/17/2020
Observer Name
B
Region
Salt Lake » Big Cottonwood Canyon » Brighton Perimeter
Location Name or Route
Brighton Periphery
Weather
Sky
Overcast
Precipitation
Heavy Snowfall
Wind Direction
Southwest
Wind Speed
Light
Weather Comments
Cloudy all day with intermittent Snow Showers that increased as the day went on. Temperatures mild for season. Winds were very active during morning hours at 8000 in Silverfork, and appeared to die down slightly in the late afternoon. Wind Blown Moderate on ridge lines and light at mid elevations. Around 1500, snowfall ramped up to at least S3 and increased until exiting at 1730.
Snow Characteristics
New Snow Depth
4"
New Snow Density
Low
Snow Surface Conditions
Powder
Snow Characteristics Comments
Excellent powder riding on all aspects. New snow accumulations for the day were close to 6 inches by 1800. Low angle terrain rode well and was bottomless.
Red Flags
Red Flags
Recent Avalanches
Heavy Snowfall
Wind Loading
Cracking
Collapsing
Poor Snowpack Structure
Red Flags Comments
As noted by all in previous observations, Poor Snowpack Structure is Widespread. Of note ESE aspects were the most sensitive for Collapsing, yet multiple avalanches triggered on NE and NNE steep terrain in the Dog Lake Chutes. See Avalanche report. Collapsing and Cracking was occurring throughout the tour on all aspects and slope angles. Remote Triggering was also happening.
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Increasing Danger
Problem #1 Comments
Widespread PWL's on all aspects with Crust Facet Sandwiches on the Southerlies appearing to be the culprit layers of concern.
Avalanche Problem #2
Problem
Wind Drifted Snow
Trend
Same
Problem #2 Comments
Winds throughout the range have been in the Moderate to Strong category since last night and there is ample snow available for Transport. Soft Wind Slabs of up to 60 cm were observed.
Observations in terrain covered indicated a Considerable Danger, yet upper elevations receiving Winds likely were High Danger.
Friday Considerable.
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
Considerable