Quick report
We snowmobiled up on East Angle today. Weather conditions varied throughout the day. Before noon, high broken clouds overhead gave way to patchy sun. Occasional solar input was enough to moisten snow on solar aspects below 10,000'. As the day progressed, a storm moved into the Togwotee area around 1:00 pm bringing heavy snowfall (~1"/hr). During our time in the storm, ~1 - 2" of snow fell at 9800'. The storm was fairly isolated geographically. As we drove back towards Jackson, clouds gave way to patchy blue sky with no evidence of recent snowfall along the highway. Winds were light-gusting to moderate from the west during the storm. We did not note any signs of instability during our ride. We identified an avalanche that most likely occurred 2 days prior during a warming period. See the attached avalanche for more information.
Weather
- Air Temp
- 20
- Cloud Cover
- overcast
- Wind Loading
- light
- Recent Snowfall
- 4
- Snow Avail For Transport
- moderate amounts
Avalanche
- Size
- D2.5 R2
- Type
- HS
- Aspect
- SW
- Elevation
- 9800 ft
This avalanche failed on a buried persistent weak layer (depth hoar). The crown height averaged 23 inches but varied from 16 - 45 inches deep. Occurring on a SW aspect at 9800', this avalanche took the majority of the season snowpack with it and most likely occurred two days ago (2/20) during the initial phase of a warming trend. While we are not exactly sure what triggered this avalanche, we think it's likely a chunk of snow falling from a tree limb was the tipping point. During our crown profile, we performed a CT and PST. We scored a CT20 on the depth hoar layer. On that same layer, we scored a PSTend 15/100 indicating very weak depth hear that propagates easily. Note the thinner, rocky section of the crown in the second photo. This is a visual representation of the problem areas where you are more likely to impact these deeper weak layers.