Observation: Tower Mountain

Observation Date
1/8/2021
Observer Name
Andrew Nassetta
Region
Uintas » Tower Mountain
Location Name or Route
Tower Mountain
Weather
Sky
Clear
Weather Comments
Another beautiful day in the Uintas above the valley inversions. Temperatures were mid-teens at 0900 at 8,000k arriving at the trailhead. Skies were clear where we staged and moved on with the day. Climbing to 9-10k, the inversion presented mild temps and beautiful weather for working around the mountains. 1300 thin and whispys began to roll in as temps began to drop and a slight wind from the northwest came about.
Snow Characteristics
Snow Surface Conditions
Powder
Wind Crust
Snow Characteristics Comments
Skiing and riding conditions are certainly improving, slowly but surely. These nickel & dime storms aar stacking up slowly, but still are leaving us far behind our average mid-season snowpack in the Uintas. Although decent riding is able to be found at upper elevations, in sheltered, gentle terrain -- that's about it! Our biggest problem, aside from an extremely weak snowpack structure set-up across much of the range, is the lack of snow at low-mid elevation, preventing even decent travel from happening. (Of course the lack of snow in general)
Red Flags
Red Flags
Recent Avalanches
Wind Loading
Cracking
Collapsing
Poor Snowpack Structure
Red Flags Comments
Todays mission was to find where our facet/crust/facet sandwiches live -- the combination responsible for a lot of the avalanches we have seen. Throughout travels, a number of holes were dug attempting to track this weak layer combo, and how reactive it is and will continue to be with more weight added to the snowpack. 9,000' and above, from Northwest to Southeast I found this structure. Although each zone varied in snow depth and weak layer strength, the structure and distribution of the FCF combo was noted above 9k from NW through SE. 9/10 ECT's throughout today's travels produced propagation on this weak layer combo. The final pit of the day near tower mountain was dug just adjacent to a recent cornice triggered an avalanche. See below for details.
Avalanche Problem #1
Problem
Persistent Weak Layer
Comments
One of many holes from today displaying the poor structure, and FCF combo highlighted by the red line.
Spotted this slide earlier in the week but did not have time to make it out to the site. Upon further investigation, the slide ESE 9,800' (HS-NC-D2.5-R2-O) was about 2-3' x 250' and was caused by, what seemed to be, natural cornice fall. Accompanying the snowpilot image include, that was on a similar slope in aspect, elevation and in the same zone as this avalanche are a few other images. The second is of the slide from a distance on the road cut. And the third photo is of a 3.5 meter probe stuck in the middle of the debris pile buried nearly to the top, something to think about when you go out probe shopping -- bigger the better.
And finally one of the many expamples of red flags noted today. I had my partners play around and test many test slopes in the travel area today producing similar results. Look close and you can see the shooting cracks remotely triggered from a collapse above. All we are missing for the ingredients of an avalanche are there except.... slope! Weak Layer + Slab + Slope + trigger (us of course) = Avalanche
Another reminder that the UAC Transceiver Checker is up and running at the Nobletts traihead. Up next, our new BCA Trainceiver Training Park -- stay tuned!
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
Considerable