Dangerous avalanche conditions exist and you are likely to encounter old wind slabs at mid and upper elevations on all aspects. Additionally, the most recent storm snow is sitting on top of a weak and faceting base. You can find this weak facet base on all aspects and elevations. To avoid these problems, choose to ski and ride on slopes that are less than 30 degrees, and aren't below or adjacent to avalanche terrain.
Winds have been shifting directions all over the compass, and creating wind slabs at tree line and above on all aspects. Very cold temperatures have been keeping the most recent storm snow light and available for transport. Wind effect can be seen on all aspects, and cracking underfoot as well as density changes are key indicators of wind slab development.
Multiple weak layers exist throughout the snowpack right now. The surface hoar that developed on New Year’s Day was buried intact by the most recent storm event. The buried surface hoar can be found most intact on North facing aspects, where the sun had less of an opportunity to breakdown this weak layer before the storm rolled in. Further down in the snowpack you can still find the buried surface hoar that developed on November 24th in extremely isolated areas. To find this weak layer, you would have to look on North facing aspects, at tree line and above in sheltered areas amongst openings in the trees. We haven't seen this layer propagate recently, but with new weight and stress being added to the snowpack, it could become reawakened.
Recent drastic weather changes have contributed to a potentially dangerous and complex snowpack. The most recent storm that delivered over 2 feet of snow to the region was accompanied by very strong and changing winds. This combination formed widespread wind slabs on aspects that we typically don't see wind slabs form. Following the heavy amount of new snowfall, temperatures plummeted below zero for multiple days in a row, with windchill values reaching -40 degrees. The rain crust layers in the lower portion of the snowpack have been faceting and weakening due to prolonged cold temperatures. our once stable and "right side up" snowpack has morphed into a slab sitting on top of a weakening and faceting base. Just prior to the recent snow, Surface hoar that formed on 1/1 and was preserved on less sun affected aspects (NW-N-NE). Recent stability tests haven't produced propagation on this layer, but it is worth investigating and testing before thinking about committing to terrain that fit its location. New snow added on top of these weak layers have the potential to overload and reactivate them.
A new storm system will roll into the region starting tonight. The storm is forecasted to deliver a heavy amount of snow Wednesday, with snow totals on the high end equaling up to 18" throughout Wednesday and Wednesday night. With another significant amount of snow expected to fall in a short period of time, expect the avalanche danger to increase.
Several natural and skier triggered avalanches have been observed in the Silver Valley/St. Regis zone this past week. This is a testament to how dangerous the snowpack is for the time being. Consider dialing back terrain choices, and seeking low angle (less than 30 degree) slopes to recreate on today. Lot's of good snow just waiting to be harvested can be found on lower angle terrain.
