Observation Date
2/21/2021
Observer Name
Staples, Vacey & crew
Region
Uintas » Upper Weber Canyon » Middle Fork Weber River
Location Name or Route
Middle Fork of Weber River
Comments
The new snow has really settled and the snowpack overall has become a lot more supportable. When you step off your sled, you don't always sink to the ground. Snowmobiles generally stay on top of the snow and don't trench to facets near the ground.
I have been consistently getting ECTP's in the 20s usually 20-40 cm's (about a foot) above the ground.
We dug a lot of snowpits in different places today. In some places the snow is 5-6 feet deep and weak facets near the ground are getting hard to impact. Plenty of other places still have a thinner snowpack. You know when you find it because your sled easily trenches or your spindle drops to the ground or you step off the sled and your boots go to the ground.
The facets remain weak and sugary. It's getting slowly harder to trigger avalanches because they have slowly adjusted to the load of snow from Valentines weekend.
The most likely places to trigger a slide are also the places where you will be most concerned about hitting rocks. These places are sometimes easy to identify and sometimes hard to identify. I'd say any places with snow less deep than a ski pole is a good place to trigger a slide. Bascially, we need two things to get an avalanche right now (1) we need some extra loading and stress which will come from wind loading, and (2) we need to find a place where we can impact the weak snow which is usually about a foot above the ground.
Below is a video of the propagation saw test (pst)
A propagation saw test measures the critical crack length in a weak layer under an isolated column of snow. It is the length of a crack after which it can propagate on its own. We use a saw to artificially start the crack in the weak layer. In theory, the shorter the critical crack length, the easier it is to trigger avalanches.
Video
Below is a snowpit in a WNW aspect on the west end of Notch Mtn. It was a thin, weak snowpack and the perfect place where you could trigger an avalanche or trigger one from above. Notice that it's not much deeper than my shovel. I did a PST in this location (no photo, no video) and barely had to touch the weak layer before it propagated a crack to the end of the column.



Below is a snowpit from the west side of Mt Watson on a WNW aspect. It was lower and in the trees and more sheltered and deeper. This is the location where we filmed the PST in the video above.


What's the avalanche danger? It's a tough call becuase the likelihood of triggering a slide is very very slowly decreasing. It's not hair trigger. However, these are still dangerous avalanche conditions that require careful snowpack evaluations, conservative decision making, and cautious route-fnding. By that definition, it is CONSIDERABLE.
What's the easy answer? (1) try to find slopes with deep snow where you don't think that you'll hit rocks. (2) Simply avoid avalanche terrain, avoid any slope steeper than 30 degrees and aovid being under slopes steeper than 30 degrees.
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
Considerable
Coordinates