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Observation: Moab

Observation Date
12/29/2020
Observer Name
Chris Benson
Region
Moab
Location Name or Route
Gold Basin
Weather
Sky
Few
Precipitation
Light Snowfall
Wind Direction
North
Wind Speed
Moderate
Weather Comments
Precipitation tapered off towards mid day. No valley winds. Late afternoon/sunset, northerly winds picked up at ridgetop and observed blowing snow.
Snow Characteristics
New Snow Depth
15"
New Snow Density
Low
Snow Surface Conditions
Powder
Snow Characteristics Comments
We found around 15" of new snow, with more at higher elevations and in places where some wind-loading has occurred. Most southerly slopes below treeline had only the new snow. In contrast, higher elevation and west through north through east aspects had old snow underneath the storm snow.
Red Flags
Red Flags
Recent Avalanches
Cracking
Collapsing
Poor Snowpack Structure
Red Flags Comments
We observed several small avalanches, mostly on north facing aspects. These were R1-R2, and D1-D2. Dozens and dozens of shooting cracks on a variety of aspects, elevations and slope configurations. The most consistent pattern though, seemed to be northerly slopes that contained the crust-facet combo near the bottom of the snowpack. These almost invariably displayed long (30-50') shooting cracks, which sometimes produces 1-2' of slab movement. Throughout the day, the leader would often feel a collapse while breaking trail, or in spots where multiple people gathered, we experienced several large collapses.
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Decreasing Danger
Problem #1 Comments
The basal crust-facet combo seems to be reactive to the new snow load. We also observed a possible weak layer around 40-50 cm down in the new snow/ old snow interface. While this layer failed in an ECT, we suspect that much of the cracking we observed was caused by a failure on the basal crust-facet combo.
Avalanche Problem #2
Problem
Wind Drifted Snow
Problem #2 Comments
We observed variable snow depths across short distances suggesting that wind has redistributed some of the storm snow. Overall though, most slopes near and below treeline showed relatively little wind effect. Towards the end of the day, northerly winds picked up and snow was being transported onto southerly slopes in the alpine.
Snow Profile
Aspect
Northeast
Elevation
10,200'
Slope Angle
38°
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
Considerable
Coordinates