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Observation Date
12/4/2017
Observer Name
B
Region
Salt Lake » Big Cottonwood Canyon » Brighton Perimeter
Location Name or Route
Brighton to Point Supreme/Dry Fork, Rocky Points, and Dog Lake Chutes
Weather
Sky
Overcast
Precipitation
Light Snowfall
Wind Direction
Northwest
Wind Speed
Light
Weather Comments
Snowing on and off the majority of the day at an average of S1 rate wise. Acummlations during the day appeared to be 2 to 3 inches of light density snow above 8700 feet with the BCC/LCC Ridgeline areas receiving the lions share. Winds were mostly light out of the WNW. Little to no wind transport of wind blown observed. Temperatures remained seasonably cold never climbing out of the teens and dipping later in the day. Skies were overcast almost all of the day with only a few periods of direct sunshine, and the south faces remained cold and dry.
Snow Characteristics
New Snow Depth
12"
New Snow Density
Low
Snow Surface Conditions
Powder
Wind Crust
Snow Characteristics Comments

Overnight and into the early morning hours the HST was 11 inches at 8000 feet, and 12 to 14 at the upper elevations. The initial pre-frontal pulse laid down 2 to 3 inches of grauple; and thed storm came in with active/strong westerly winds. As a result thinner new snow areas were observed on exposed W and NW aspects with wind whales and scouring evident in the most exposed areas. It appeared that the facets associated with the previously cited rain crust were destroyed in the exposed terrain areas. In more sheltered areas as indicated by the video below, these facets remained in place and active.

Riding was superb in light density mostly bottomless turning.

Red Flags
Red Flags
Wind Loading
Poor Snowpack Structure
Red Flags Comments
No cracking or collapsing. It appeared that the 1 inch of new water weight was not enough to activate any of the multple buried weak layers. ECTP16 SC, Q1 test scores indicate a potential for the facets above the rain crust to be an issue in steep protected northerly facing terrain, but these appear to be very isolated. There were also isolated areas of fresh wind slabs associated with the latest event and it appears that these may have been the biggest potential issue to avoid.
Avalanche Problem #1
Problem
Wind Drifted Snow
Trend
Decreasing Danger
Problem #1 Comments

See above, and of note it was easy to get the upper 2 to 4 inches sluffing loose snow dry avalanches on steep terrain. The isolated pockets of cross and direct loaded wind slabs that were observed were avoided. Of note, the strong storm driven winds at the upper elevations appeared to be too intense to load many of the upper leeward starting zones.

Avalanche Problem #2
Problem
Persistent Weak Layer
Trend
Same
Problem #2 Comments

Regardless of the previously cited lack of water weight to potentially activate the multiple buried persistent weak layers, this problem still exists and may still be possible in very isolated areas that received wind loading and deeper slab development. Graupel pooling may also be offering a potential in isolated areas below cliff bands. See video depicting DH, recystalized graupel and NCF's .

Also of note, warmer temperatures and direct sunshine on steep southerly facing slopes may help initiate wet loose avalanches over the next 48 hours during the middle of the day when the sun is at it's apex. The trend for these types of avalanches will be increasing.

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