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Observation: Back Bowls

Observation Date
1/11/2017
Observer Name
B
Region
Salt Lake » Big Cottonwood Canyon » Brighton Perimeter » Back Bowls
Location Name or Route
Brighton Back Bowls
Weather
Sky
Overcast
Precipitation
Heavy Snowfall
Wind Direction
Southwest
Wind Speed
Strong
Weather Comments
A mix of obscured and overcast skies. Definitely periods of decent visibility and good enough for Observations. Temperatures continued to stay mild with highs at 9000 feet in the upper 20's. Strong Winds and especially in the Alpine. Transport was Intense and may have been mostly sublimating at times. Winds appeared to be variable and shifting throughout the day, yet mostly WSW. Snow fall at the 8000 feet appeared to taper off after 1000. In Brighton, there never appeared to be a lull. S3 to S4 at times.
Snow Characteristics
New Snow Depth
15"
New Snow Density
Medium
Snow Surface Conditions
Dense Loose
Wind Crust
Snow Characteristics Comments

Easily 15 inches at 8000 feet for the past 24 hours with much more up in the Brighton area. Precipitation Particles were mostly mixed forms with predominantly Graupel and also rimed stellars. And, at times when the wind would die down, there was Light Density Snow. Riding was supportable and mostly fast in the Alpine. Low Angle terrain rode well. The winds and Graupel made for buoyant conditions. Later in the day the depth in undisturbed areas was significantly deep, up to your knees. An incredible day of powder riding

Red Flags
Red Flags
Heavy Snowfall
Wind Loading
Cracking
Collapsing
Poor Snowpack Structure
Red Flags Comments
Besides the Control work at Brighton, there were no Naturals and or other avalanches observed. Cracking was observed in areas where the Winds had made dense slabs, and these cracks were able to be made on 30 degree slopes. Slope angles were kept down due to the Heavy Snowfall and Winds. Weaknesses in the new snow were easy to identify with the daytime graupel layers riding over much Lighter Density snow. Easy and Very Easy Hand Shears were possible. Wondering how and if any of those buried NSF’s that were formed and buried last Friday will become reactive. I saw nothing in the past few days to indicate they are reactive, but I have no doubt that Gagne’s Snow Pit Test results from Tuesday that indicated a propensity for Propagation may be offering possibilities. We appear to be locked into a more Maritime-like Flow that may or may not be allowing things to adjust, settle out and heal much faster than we are used to here in Utah.
Avalanche Problem #1
Problem
Wind Drifted Snow
Trend
Decreasing Danger
Problem #1 Comments

See above, and since 1900 hours the Winds have appeared to die down at Mid Elevations; yet they still are active on the ridge lines.

Avalanche Problem #2
Problem
New Snow
Problem #2 Comments

See above for Poor Snowpack Structure in the many layers that have been created over the past 48 hours. The most reactive was the dense graupel layer resting on a possibly temporary Weak Layer of Lighter Density snow, and this was 6 to 8 inches down.

Danger today appeared to be Considerable due to the Winds and Heavy Snowfall. For Thursday, if the Winds aren't an issue, the Danger should be Moderate with Isolated possibilities of large Wind Slabs on E, N and NW aspects.

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