South Rockies

There is a lot of uncertainty surrounding the intensity of precipitation amounts in the region. Certainly in areas where the freezing level is forecast to rise in combination with the potential for snowfall, the avalanche danger will be elevated.

Moderate - Intensity of incoming weather systems is uncertain on Wednesday

WEDNESDAY: Scattered flurries with 5 to 10 cm of new snow overnight Tuesday into Wednesday, moderate to strong southwest winds, freezing level rising to 1500 m and likely higher on the eastern slopes.THURSDAY: Clearing with isolated flurries, strong southwest winds, freezing level around 1500 m.FRIDAY: Mainly cloudy, no precipitation, light westerly wind and freezing level around 1200m.More details can be found on the Mountain Weather Forecast.

A Mountain Information Network (MIN) report from Waterton Park on Friday shows a large size 3 deep persistent slab avalanche triggered by a smaller wind slab on a feature with highly variable snow depths. Although an isolated event, this avalanche highlights the possible consequence of our tricky persistent slab problem, especially with the incoming change of weather.

Recent widespread wind affect in exposed alpine and treeline terrain has formed reactive wind slabs on lee features. The mid pack is quite variable throughout the region and the structure depends on snow depth. In deeper snowpack areas, the snowpack appears to be well settled and right side up with isolated concerns for the mid-December facet layer found 50 to 80 cm deep. In shallow snowpack areas and lower elevations, the snowpack is heavily faceted and there are concerns for the mid-December weak facet layer as well as weak basal facets. If a persistent slab is triggered from thinner snowpack areas it may release on the basal facets resulting in a full depth avalanche. Triggering these deeper weak layers will become more likely this week as warm temperatures soften the overlying slab.