Quick report
While I did not find any instabilities, I have concerns about what warming and rain will do to the snowpack in the coming days. This is snow that has been and stayed cold, with consistent well below freezing temperatures. It has made for some great early season skiing, but this type of snow is typically not tolerant to rapid change like warming and rain.
Wet snow avalanches should be on your horizon in the coming days, and remember that these can have surprisingly low start zones.
The coming days may be better for reading than venturing out into avalanche terrain. So I thought I’d share a paper I find really interesting on wet snow (and the usefulness of PST in particular),
Weather
- Air Temp
- 23
- Cloud Cover
- obscured
- Wind Loading
- light
- Recent Snowfall
- 6.1
- Snow Avail For Transport
- small smounts
At lower elevations found slightly warmer temperatures and lower winds than expected (but was in sheltered terrain). As I gained elevation a thick fog layer significantly obscured visibility at about 3500 ft. Winds did pick up through the day/as a gained elevation and was less sheltered. 3500 ft and below had soft snow in the trees, which I noticed was significantly less as I was skiing down and you could see small amounts of snow being pulled off of the branches. At 3800 ft the snow in trees was heavily rimed and was not being moved by the west winds of the day.
Snowpack
Since there have been some good observations from east-facing terrain (thank you backcountry community!) planned to look at the developing snowpack in western aspects. Knew that visibility would be non-existent, so at least was going to settle with getting a sense of the snowpack structure.
This sample set is small, from a mostly sheltered area, and not avalanche terrain, so is not perfectly representative, but the snowpack structure had similar composition to previous observations that had mentioned melt-freeze crusts.
Consistently found at and below Jacob's Ladder was 2-3 inches of dry cohesionless snow. This was looking for snow that was not compacted from skier traffic. There was slightly firmer snow that still lacked cohesion to the bottom (compacted snow felt far stiffer). Near the bottom found an old melt-freeze crust. This crust was disintegrating (likely from sustained cold temperatures).
I was looking for a hard, icy layer that had stayed intact as this may be a concerning interface looking ahead into next week where warm temperatures and rain will impact the snowpack. Intense rainfall can pool at this layer and works to lubricate the interface with snow/slab above it. Even if previously there had been no reactivity observed on this interface, it can be a potential bed surface. I did not find any evidence of a surface like this, as all crusts I found were disintegrating.
At Jacob's Ladder found a thin rime crust over the 1-2 inches of snow. The snow was still soft underneath, but as winds were picking up this thin layer was limiting some of the snow moving. The snow in this area was firmer, but not boot supportable as you would easily posthole up to your thigh without skies/snowshoes or only traveling on compacted surfaces (and this is a maybe).
About 300 ft above Jacob’s Ladder found firmer and icy surfaces that were starting to become boot supportable as well as a lot of riming.