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Observation: Superior

Observation Date
4/21/2017
Observer Name
Greg Gagne
Region
Salt Lake » Little Cottonwood Canyon » Superior
Location Name or Route
Upper LCC
Weather
Sky
Obscured
Precipitation
Light Snowfall
Wind Direction
Northwest
Wind Speed
Light
Weather Comments
Beautiful morning. Fresh snow & temps in the upper teens. Winds were gusting from the NW, but just along ridgetops.
Snow Characteristics
New Snow Depth
8"
Snow Surface Conditions
Powder
Wind Crust
Snow Characteristics Comments

20 cms (8") new. Quite a bit of graupel mixed within the storm snow, but the dense snow was well-bonded to the old snow surface. Density of storm totals are 10%, but a right-side up storm with lighter snow at the surface.

Some fresh wind drifts just along the ridges, but these were not sensitive.

The old snow surface was frozen and supportable with a 5-10 cm (2-4") crust, with damp grains underneath.

Comments

Travel today was Toledo -> Holy Toledo -> LSB -> Superior. Storm snow was bonded well to the old snow surface, but I was able to get long-running sluffs in the top 5 cms (2") of low-density snow on steeper aspects. The few wind drifts I found were just along the ridges, and not sensitive to any stability tests.

On steeper slopes, the hazard was in the low end of Moderate where the risk was long-running sluffs. On slopes < 35 degrees, the hazard was Low.

It was very poor visibility with clouds and fog obscuring the views (no photos), but I did not see any other activity than the loose sluffs we triggered on steeper slopes.

Exited the canyon at 11 am and the clouds and cool temperatures kept the snow surface cool. If the sun comes out at all, this new snow will almost instantly become sensitive to any warming.

Finally, dug a few quick pits on upper elevation north aspects between 10.5 and 11K. Underneath the frozen, old snow surface are damp grains, so there has been warming - and possibly rain - on upper elevation north facing slopes. But other than some rollerballs, very little wet activity so far this season. I was finding some melt-freeze crusts in the top 45 - 60 cms (18-24") and this structure is something to watch as these upper elevation aspects warm and melt-water moves through the snowpack where these crusts may inhibit the flow of water, creating a possible wet slab situation. Not a concern until things warm up.

Snow surfaces on Saturday morning will depend upon sun and warming Friday afternoon. Am guessing with a cold and clear night, upper elevation north aspects will be still be soft and dry early Saturday morning. Wet, loose activity is the concern for Saturday.

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