Observation: Brighton Perimeter

Observation Date
1/4/2021
Observer Name
B
Region
Salt Lake » Big Cottonwood Canyon » Brighton Perimeter
Location Name or Route
Brighton Periphery/Pioneer Bowl Area
Weather
Sky
Overcast
Precipitation
Light Snowfall
Wind Direction
Southwest
Wind Speed
Moderate
Weather Comments
Forecast verified: Clear skis am with increasing cloud cover and Overcast by mid afternoon. Temperatures moderate throughout the day and rising after sundown, with Light Snowfall by 1630. Winds Light am and ramping up by mid afternoon into the Moderate to Strong Category by 1500. Wind Blown Moderate to Strong by 1500.
Snow Characteristics
New Snow Depth
3"
New Snow Density
Medium
Snow Surface Conditions
Powder
Wind Crust
Damp
Snow Characteristics Comments
Cold dry snow above 8300 feet with the lower elevations suffering from afternoon warming temperatures. Riding above 8500 feet actually improved significantly with the dribbles of moderately denser snow from the past few days in untracked areas. The winds appeared to help greatly errasing and or filling in many of the old tracks. Significant/widespread wind damage and effected areas by late afternoon with the winds getting well down into the mid elevation terrain.
Red Flags
Red Flags
Wind Loading
Poor Snowpack Structure
Red Flags Comments
Moderate to Strong Wind Blown observed. Poor Snowpack structure continues to be the norm, yet as observed in Mineral Basin four days ago, in areas that have an HS of at least 85 cm there is beginning to be the initial turning around of some of the buried weak layers. Reluctant to even note this, as this does not indicate a move towards increased stability.
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Increasing Danger
Problem #1 Comments
As noted above, in the upper elevation terrain that has close to a meter of snow, the mid pack advanced facets were showing early signs of chaining. This combined with the consolidating of the overriding slab above this buried weak continues to indicate that the ECT Tests may be providing "false negitives" for identifying the propensity for propagation in our snowpack. The ECT test may not be the best test for our snowpack at this depth with the overriding slab dissipating the compressional forces of the loading steps. As stated before, the best test for identifying the potential reactivity of our current PWL (in areas with a deeper snowpack) may be the PST.
Pit at 9400 feet, WNW, 20 degree slope angle, HS: 85 cm: the December pre-storm interface was down 41 cm, and in this location and there were 5 to 7 cm of 3 mm advanced facets that were showing early signs of chaining. Scores at this interface were: ECTN and CTM SC. Most interesting were CTM SP at 26 down in .5 mm facets (December Storm-18 hour Break in precipitation when we got NSF’s and or SH developing). This layer continues to remain reactive and is worrisome, as it may initiate first when we get a load and then step down.
Avalanche Problem #2
Problem
Wind Drifted Snow
Trend
Increasing Danger
Problem #2 Comments
As noted above, active winds were loading multiple aspects from 9000 feet and above. Loading from the winds on any areas with our poor snowpack structure may result in Natural activity, and at least Likely human triggered avalanche potential if the overnight and Tuesday storm comes in within the the upper reaches of the forecast values.
Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
Considerable