Observation: Brighton Perimeter

Observation Date
12/17/2015
Observer Name
Kikkert
Region
Salt Lake » Big Cottonwood Canyon » Brighton Perimeter
Location Name or Route
Brighton Perimeter
Weather
Sky
Clear
Wind Direction
Northwest
Wind Speed
Light
Weather Comments
Pretty light winds along the Pioneer ridgeline, clear and cold
Snow Characteristics
New Snow Depth
7"
New Snow Density
Medium
Snow Surface Conditions
Powder
Snow Characteristics Comments

Sorry for the late observation, couldn't get anything out earlier due to evening avalanche classes yesterday; however, wanted to send something in due to some interesting results we had with the day class on south facing.

Was hard to tell new snow depths due to the strong NW winds that whipped everything around, but Brighton reported 7". Wind was denser around the compass due to winds, but in the Brighton perimeter, did not find very many stiff slabs.

Red Flags
Red Flags
Recent Avalanches
Heavy Snowfall
Wind Loading
Cracking
Collapsing
Poor Snowpack Structure
Red Flags Comments
Checking almost all the boxes. Outside of the areas heavily loaded by NW winds (PC ridgeline, wolverine cirque, etc.) things were still just shy of the tipping point, but oh so close. Cracking and collapsing most everywhere.
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Same
Problem #1 Comments

No need to reiterate the poor structure on shady slopes, just wanted to provide an observation from south facing. Dug with my class on south facing green slope in Snake Creek canyon to allow comparison with shady slopes. Lots of crust/facet sandwiches on the bottom, but most notable was a thin layer of small facets at the old snow/new snow interface. Looks like they probably formed around Dec 11th, and were sitting on a finger hard slab from the strong winds we had from about Dec 7th to Dec 9th. Very easy stability test results on this layer with good energy, ECTP 9 Q2. Not sure if some of the recent slides on south facing slopes (e.g., superior.) failed on this layer or elsewhere. The take home is that upper elevation south facing slopes may not have the bottomless facets that shady aspects do, but at least some of them have persistent weak layers.

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