Observation Date
11/16/2015
Observer Name
Greg Gagne
Region
Salt Lake » Little Cottonwood Canyon » Alta Periphery
Location Name or Route
Rocky Point/Catherine's Area
Weather
Sky
Obscured
Precipitation
Light Snowfall
Wind Direction
Northwest
Wind Speed
Moderate
Weather Comments
-6C with gusty NW/N winds.
Snow Characteristics
New Snow Depth
8"
New Snow Density
Low
Snow Surface Conditions
Powder
Snow Characteristics Comments

Was generally finding 15-20 cms (6-8") storm snow in the early am, though totals ended up higher. Was also not finding any wind-affected snow apart from a few drifts along ridgelines, but I also think winds increased from the North as the day progressed.

Red Flags
Red Flags
Heavy Snowfall
Poor Snowpack Structure
Red Flags Comments
Anytime we get new snow on top of a weak existing snowpack it is clearly a red light. I do not think there was sufficient water weight to elevate the hazard however.
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Same
Problem #1 Comments

With new snow on top of a persistent weakness, I guess we are moving into a period of persistent slab instability.

Snow Profile
Comments

Always nice to have a storm come in on the high end of expectations - with decent accumulations last Tuesday/Wednesday, this makes 2 in a row that exceeded expectations of a storm that was forecasted to split.

Today's route was Catherine's Area - cruising along Rocky Point and exiting So Long. Dug about 10-12 pits (they are pretty easy to dig to the ground) and was finding the following:

- The snow that fell Nov 11/12 (last Tuesday/Wednesday) was not as weak as I was expecting. I haven't looked at any snow since last Wednesday, but I am guessing the warm temps and relatively short duration (4 days) inhibited the faceting process. This layer is largely decomposing fragments with some faceting. Unsurprisingly, I was not finding any of the surface hoar that people noted last Thursday.

- The weakest snow continues to be the old snow down at the ground. These are 1-2 mm facets and depth hoar (with some striations on the depth hoar) and the layer is about 5-15 cms thick on northerly aspects. In all my pits I was either getting a failure down at the depth hoar layer upon isolation, or very easy shears at this layer (STV or STE).

- I also was finding a few temperature crusts on W aspects with facets below.

Take home message for me is that (1) the weakest snow is down near the ground, and (2) the snowpack on any slope above 9000' facing NW through NE can be presumed to have weak snow underneath.

I don't think today's storm was enough of a load to trigger these buried weak layers, but any bump in wind loading on Northerly aspects may create more sensitive conditions.

This isn't the end of the world, and typical early season conditions often include this type of weak snow that forms from Fall storms. I was pleased to see the storm snow from last week didn't look as weak as expected.

Happy winter everyone!

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