South Rockies

Fair - Forecast snowfall amounts are uncertain on Saturday

A ridge of high pressure is expected to move into the region overnight. Northwest winds are expected to continue to be gusty and strong in the alpine and at treeline on Thursday. Continued high pressure is forecast for Friday morning, before a low pressure system moves into the region from the Pacific in the afternoon. Southwest wind and moderate precipitation is forecast to begin in the late afternoon or early evening. Snow and wind should continue overnight and into Saturday. The freezing level is expected to drop down to near valley bottoms on Wednesday night, and then rise to about 1000 metres on Thursday.

A remote-triggered size 2.5 avalanche was reported from the Northern Elk Valley at 2350 m on Tuesday. The crown was 60-70cm deep and the avalanche initiated in wind slab overlying surface hoar. Numerous avalanches sized 1.5 were reported on Sunday (and likely Monday, although we didn't hear about them) at all elevations and focussed predominantly on easterly aspects. Remote-triggering was reported, where the avalanche was triggered from up to 100 m from where it initiated.

Gusty wind has transported snow into windslabs at all elevations. In southern and western parts of the region, 40-50 cm of recent snow sits of a highly reactive weak layer comprising surface hoar (most prevalent in the west of the region), sugary facets on shady northerly aspects and sun crusts on solar aspects. This interface has started to react to human-triggering. Certain features of the reactivity, such as remote triggering and the ability to initiate avalanches on relatively low angled terrain, point to this weak layer shaping up to be quite dangerous. In areas further north, less snow has fallen on this interface--in the northern Elk Valley for instance, only around 15-20 cm lies above this interface. In lower snow areas, avalanche activity will likely lag behind higher snow areas, except for areas which have seen significant wind transport. In general, the mid-pack is quite strong in most locations. However, lingering concern remains for basal facets, particularly in shallower snowpack areas with steep, rocky start zones.