Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2
The January/February drought resulted in widespread weak, faceted snow across the northern end of the compass at mid and upper elevations. These weak faceted grains are now covered by roughly 8-16" of new snow, shallow wind drifts, and some variable crusts from the past week. Human triggered avalanches into this layering have been sporadic but they have occurred almost on a daily basis over the past week or so. Areas include Neffs, Porter Fork, White Pine, Little Water, and Mill A Gulch of BCC and generally in the mid-elevation bands that held some of the weakest snow.
With 1-2' of snowfall expected through Sunday night, these avalanches will become increasingly active and dangerous (larger and wider) in steep northerly terrain. It's possible that you will be able to trigger them from a distance. But I'll caution that it will be tricky: there is a lot of spatial variability with this layering across aspects and elevation bands and cracking and collapsing may not provide early clues to instability. This often leads to accidents.
What you can do is see for yourself: my own touring parties yesterday and on Wednesday found conditionally unstable conditions with snow tests and just elected to ride southerly aspects and low angle shady slopes. Mark explains the snow conditions and outlook below -
