Observation: Mill D North

Observation Date
12/21/2013
Observer Name
Greg Gagne
Region
Salt Lake » Big Cottonwood Canyon » Mill D North
Location Name or Route
Little Water Peak (BCC/MCC ridgeline)
Weather
Sky
Obscured
Precipitation
Light Snowfall
Wind Direction
Northwest
Wind Speed
Moderate
Weather Comments
Some light riming along windward aspects > 9000'. A few occasional snowflakes falling. Winds were blowing Moderately out of the NW along the ridges, however we were not finding any fresh wind drifts (admittedly Little Water Peak is not a very upper elevation, windy location.)
Snow Characteristics
New Snow Depth
2"
New Snow Density
Low
Snow Surface Conditions
Powder
Snow Characteristics Comments

Just a few cms storm snow at best.

Red Flags
Red Flags
Poor Snowpack Structure
Red Flags Comments
Our poor structure isn't going away anytime soon, but no collapsing or cracking at all today.
Avalanche Problem #1
Problem
New Snow
Problem #1 Comments

Persistent slab sitting atop several faceted layers remains our primary concern, although from stability tests today I am feeling that at mid-elevation terrain (< 9500') the weak layers are slowly adjusting to the load from Thursday and the slab is losing elastic energy.

Comments

Happy first day of winter! And it did not disappoint. Even though snow totals from the Friday night/Saturday am storm we meager during the morning hours, am currently finding the best conditions of the year during this so-far marginal season. Boot top soft snow providing fun ski conditions on lower angled slopes.

Route today was throughout the north and northwest facing aspen glades of Little Water Peak and elevations remained at or below 9,500'. Some riming on trees on windward aspects at the ridge lines, but no riming found below ridges. Lots of quick pits and I was finding a 75 cm (2.5') snowpack with 15-20 cms of settled snow from the Thursday storm and Saturday morning. Really cannot find a pattern to our snowpack on northerly aspects - in some of my travels over the past week am finding rotten snow throughout, but today was finding the top 15-20 cms sitting atop a supportable 4F slab. (But of course with F-hard facets and depth hoar below that.) CT 20/Q3 and ECTP26 with Q2+ shear. Both down 45 cms in mid-November facets.

With the lack of collapsing and generally favorable stability tests, I am thinking that the hazard on northerly aspects < 9,500' is closer to Moderate than Considerable, and that you would likely need to push slope angles above 35 degrees to trigger an avalanche, although with persistent weak layers we do know slides can propagate onto gentler terrain. (I will record hazard as Considerable given the avalanching reported from Friday.)

I did not see terrain above 9,500' to get a sense of conditions above that elevation.

Photos from riming early Saturday morning. The rimed particles in the aspen glades were particularly beautiful.

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