Observation: Little Cottonwood Canyon

Observation Date
12/21/2017
Observer Name
Greg Gagne with "Gunner" Frey.

Region:

Location Name or Route
Upper Little Cottonwood Perimeter
Weather
Sky
Overcast
Wind Direction
Northeast
Wind Speed
Moderate
Weather Comments
Moderate gusts in the morning out of the N/NE.
Snow Characteristics
New Snow Depth
5"
New Snow Density
Low
Snow Surface Conditions
Powder
Wind Crust
Snow Characteristics Comments

A generous 10-15 cms (4-6") in upper LCC above 9000'.  Some wind transport along upper elevation ridgelines. Some drifts were up to 45 cms (18") but overall not very sensitive and would only crack around your skis. Dug several quick hand pits and could not find any surface hoar underneath the new snow.

Red Flags
Red Flags
Poor Snowpack Structure
Red Flags Comments
Yes, poor snowpack structure with ongoing persistent slab weaknesses, but Wednesday storm totals were nowhere enough to affect any buried layers of faceted snow. Problematic because adding these small amounts doesn't yet tip the scales, but at some point we will overload the weak snowpack.
Avalanche Problem #1
Type
Wind Slab
Trend
Decreasing Danger
Problem #1 Comments

Overall was not finding widespread wind drifted snow. Instead, was only finding smaller pockets along upper elevation ridgelines, or just below ridges. Was not finding wind drifts down off of ridges. These drifts were mostly shallow, 10-20 cms (4-8"), however some drifts were up to 45 cms (18"). Overall they were not sensitive to ski cuts and at best I could only get them to crack locally around my skis. The only ongoing concern I have with these drifts is that those that are sitting on top of faceted snow may remain sensitive.

Avalanche Problem #2
Type
Persistent Slab
Trend
Same
Comments

Route today was Grizzly -> Patsy Marley -> Wolverine -> Catherines -> Dry Fork -> Supreme area. Was focusing on the following:

- how widespread and sensitive were fresh wind drifts?

- was any surface hoar preserved underneath the new snow?

- could I get sluffs to run in the new low-density snow?

(Phone battery died very early in the morning, so no photos.)

Wind drifted snow is addressed above.

Lots of quick hand pits today as I was interested in if any of the reported surface hoar that had formed earlier this week had been preserved, and I could not identify any. It seems that the strong pre-frontal winds eroded any surface hoar. The faceted snow at the old snow surface is still evident, but the new storm snow is so low-density it does not form a cohesive slab and I could not get any clean shears with  shovel tilt test.

Could only get minor sluffing in the new snow to move, even on steeper (> 35 degrees) slopes.

Generally Low hazard, with continued Moderate hazard in the upper elevations where there is recent wind loading. Winds are forecasted to increase later Friday afternoon and there is plenty of fresh snow available for transport.

Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
Moderate
Snow Profile Coordinates