Observation Date
2/15/2019
Observer Name
B
Region
Salt Lake » Big Cottonwood Canyon » Brighton Perimeter
Location Name or Route
Brighton Periphery
Weather
Weather Comments
Clear skies in the morning became overcast by 1300. Light variable winds accelerated to at least a consistent moderate (Southerly) with strong gusts in the alpine. Wind blown and or transport was at least moderate in mid and upper elevation exposed terrain. Temperatures were at least 5 degrees cooler than on Thursday, yet they still appeared mild at all elevations until 1600. By 1700 skies have become obscured, and S-1 precipitation has begun.
Snow Characteristics
Snow Surface Conditions
Powder
Wind Crust
Melt-Freeze Crust
Damp
Snow Characteristics Comments
Mixed bag of conditions depending on elevation, aspect and exposure. Upper elevation exposed terrain had excellent fun and fast turning, on what a friend of mine calls "Backcountry Corduroy." Ski penetration only 2 to 4 cm. Interestingly, the winds were blowing so well transporting snow, that tracks and skin trails were erased within the hour. In mid elevation protected terrain, the riding was much different and very good. Bottomless graupel and mixed forms provided creamy turning. M/F crusts were found on steeper southerly exposures at mid elevations, yet reports from others stated that southerly exposures above 10,000 feet continued to hold cold snow without crust development.
Red Flags
Red Flags
Wind Loading
Poor Snowpack Structure
Red Flags Comments
Surface snow conditions appear to have significant amounts of graupel and this may present an issue for bonding of the incoming new snow on many aspects and elevations from mid to upper. Graupel pooling is already in place below cliff bands and in many steep terrain features, and this may also be an issue with the new snow and potential wind loading in the next 24 to 48 hours. Wind slabs observed today were stubborn and unreactive, yet they most likely will be growing in size as this storm progresses.
Avalanche Problem #1
Problem
Wind Drifted Snow
Trend
Increasing Danger
Problem #1 Comments
See above for Wind Slab issues, and of note these same winds and snow are obviously contributing to increased danger from the already large and overhanging cornices.
Avalanche Problem #2
Problem
New Snow
Trend
Increasing Danger
Problem #2 Comments
Storm Slab issues may be a concern, as noted above, with the potential lack of bonding due to the presence of graupel at the new snow/old snow interface. And, there are places where this graupel layer is at least 8 cm thick.
Comments
The potential also exists for slides to step down to lingering persistent weak layers: 1 meter down from the existing snow pack depth, as well as near the ground (mostly likely on repeater paths). Large triggers like Cornice Fall may help precipitate these potential larger slides.
Danger today appeared to be Moderate and isolated for Wind Loading. New snow and wind loading most likely will elevate the Danger to Considerable on Saturday for all the above factors in steep terrain where these issues persist.
Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
Considerable
