Observation: Maybird Gulch

Observation Date
2/18/2017
Observer Name
Greg Gagne and Mandy Hosford
Region
Salt Lake » Little Cottonwood Canyon » Maybird Gulch
Location Name or Route
Maybird
Weather
Sky
Obscured
Precipitation
Light Snowfall
Wind Direction
South
Wind Speed
Light
Weather Comments
Occasional gusts of wind along ridge lines.
Snow Characteristics
New Snow Depth
3"
New Snow Density
High
Snow Surface Conditions
Powder
Wind Crust
Damp
Snow Characteristics Comments

About 5-8 cms (2-3") of new snow since Friday. It had bonded well to wind slabs that formed on Thursday, and bonded fairly well to the faceted snow at the old snow surface. Dry snow > 9000', below that elevation, especially below 8500' snow surface dampened with some greenhousing. Snow quality very elevation-dependent, with quite a bit of variation with just ~300' elevation change.

Red Flags
Red Flags
Collapsing
Poor Snowpack Structure
Red Flags Comments
Did get one collapse of a wind slab on top of faceted snow. Facets underneath recent wind slabs provide poor snowpack structure.
Comments

Wandered throughout Maybird today, getting as high as 10,600'. Recent snow was bonding fairly well to the old snow surfaces. Spent a good bit of time looking at facets underneath wind slabs that formed on Thursday. I and several others were finding them to be very sensitive on Thursday. Reports from Friday were showing the wind slabs to be much less sensitive.

These slabs are pencil-hard and 5-20 cms (2-8") thick with a 15-20 cm layer of facets underneath. These facets formed earlier this past week during a multi-day period of clear with clear skies.

Was surprised to find the wind slabs not sensitive at all, and only one collapse during our travels today. Wind slabs would only break around our skis and not propagate. Below 10000' was also finding the storm snow to have bonded fairly well to faceted snow on northerly snow surfaces that were not wind loaded. It appears the layer of facets were much denser and less loose than what I was finding on Thursday.

Generally Low hazard today, with a Moderate hazard in steep, upper elevation terrain where triggering a wind slab is still possible. These are not well-connected, and likely would be fairly small. We do need to keep an eye on this structure however, which exists in upper elevation northerly terrain with preserved facets underneath recent storm snow and wind slabs. Am guessing moderate amounts of snow on Sunday will not be enough of a load to activate this weak layer, but we will have to watch this layer as it may become a future persistent slab problem.

Video provides description of snowpack structure with a wind slab sitting on top of facets.

Video
Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
Moderate