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Observation: Bonanza Flats

Observation Date
1/9/2018
Observer Name
CBrown
Region
Salt Lake » Bonanza Flats
Location Name or Route
Brighton Periphery/Bonanza Flats/Wasatch State Park
Weather
Sky
Obscured
Precipitation
Moderate Snowfall
Wind Direction
South
Wind Speed
Light
Weather Comments
Off the ridgelines winds were light gusting to moderate from the south. Moderate snowfall during the day. Snow/rain line seemed to be right about 8,000'. Warm, wet and windy, felt like the PNW.
Snow Characteristics
New Snow Depth
7"
New Snow Density
Medium
Snow Surface Conditions
Powder
Dense Loose
Damp
Snow Characteristics Comments

New snow was high moisture content. At 15:00 I was observing between 4-7" on new dense snow at 9,200' by Silver Lake, East of Clayton peak. Observed more new snow at a protected NNE at 9,200' than at 9,700 entering the wind zone. Snow is good base building material, and I wouldn't have been surprised if there was around an inch of water in the new snow.

Red Flags
Red Flags
Recent Avalanches
Heavy Snowfall
Wind Loading
Cracking
Collapsing
Poor Snowpack Structure
Red Flags Comments
Observed almost all the red flags today. Avalanches at 11:00 observed on the way to ski on road cuts. Moderate snowfall with heavy wet snow. Some wind transport, somewhat limited where traveled due to lower windspeeds off the ridgelines and the dense snow. Lots and lots of collapsing and cracking. Large areas 500'x500' or bigger collapsing and cracking all over the place. Obvious poor structure with heavy wet cohesive snow/storm slab sitting on a pile of weak snow.
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Increasing Danger
Problem #1 Comments

The tipping point is here. With an estimated inch or more of water in this heavy wet snow we are overloading the strength of the weak snow below. Surprised by how connected the storm slab was. I would expect this problem to extend into the weak snow in the mid pack, possibly going close to the ground. With the density of the new snow and the still shallow pack, I would not want to be involved in taking even a small ride.

Avalanche Problem #2
Problem
New Snow
Trend
Increasing Danger
Problem #2 Comments

Although the storm slab is the most observable concern, due to it failing or stepping into the old PWL's this is really a persistent slab problem. I was surprised by how connected the slab is evidenced by the size of the collapses I was observing.

Comments

Road cut avalanches

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