Observation: Butler Fork

Observation Date
2/23/2017
Observer Name
Greg Gagne
Region
Salt Lake » Big Cottonwood Canyon » Butler Fork
Location Name or Route
Butler Fork
Weather
Sky
Obscured
Precipitation
Heavy Snowfall
Wind Direction
Northwest
Wind Speed
Light
Weather Comments
Periods of heavy snowfall. Moderate west/northwest winds only felt along top of Circle Awl (which is not a windy location.)
Snow Characteristics
New Snow Depth
12"
New Snow Density
Low
Snow Surface Conditions
Powder
Wind Crust
Snow Characteristics Comments

Was finding storm totals since Tuesday evening of 60-75 cms (24-30").

Red Flags
Red Flags
Recent Avalanches
Heavy Snowfall
Wind Loading
Avalanche Problem #1
Problem
New Snow
Trend
Increasing Danger
Problem #1 Comments

Was not in wind-affected area, so difficult for me to determine other avalanche problems. The very low-density storm snow was sluffing, but it was requiring steeper slopes (> 35 degrees). Was finding density inversion down 45 cms (18") and unable to isolate a column. I was out in the afternoon, but from what I heard from others in the morning with very sensitive storm snow , it is likely we may have gone through a natural cycle late morning.

Avalanche Problem #2
Problem
Wind Drifted Snow
Trend
Same
Problem #2 Comments

Was able to find some fresh cornices and they were very sensitive. I was able to remotely trigger a cornice fall that pulled out a small storm slab that had some minor wind affect. Although winds were reasonable today (station at 10,500' in LCC was averaging in the teens with gusts in the 20's; station at 9800' in BCC was averaging 10 mph with gusts in the teens) there is plenty of loose, fresh snow available for transport, and any fresh wind drifts are very likely to be sensitive.

Comments

Video (taken by Shane Froebe) showing weakness within storm snow down 45 cms (18")

Video

Video showing sensitive fresh wind drifts.

Video

Photos of

- natural activity (likely earlier during the day on Thursday)

- soft slabs from cornice kicks

Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
Considerable