HUMAN TRIGGERING REMAINS VERY LIKELY. Touchy slabs exist over very weak persistent layers.
A widespread natural avalanche cycle has continued all week and natural activity remains possible this weekend
Stick to the basics: Stick to low angle terrain well away from any avalanche terrain or steeper slopes.
Human remote-triggering will remain VERY LIKELY through the weekend, even from lower angled terrain. In many areas, the storm snow has overloaded the persistent layers in the mid and lower snowpack. Natural activity has continued through the week.
Since March 8, 30-90 cm of storm snow and strong southerly winds have created storm and wind slabs at all elevations. More snow fell in the northern forecast area (Bow Summit). Settlement of the surface snow means a stiffer slab is forming, potentially allowing wider propagations.
Avalanche accident Friday, outside of Lake Louise Ski Area Boundary. A size 2.5 avalanche was triggered and failed on the deep persistent layer at the ground.
A flight to the Lake O'hara area saw further evidence of a widespread natural cycle that has occurred over the last week. Many long fracture lines were observed with avalanches to sz 3.5 all failing on midpack or deeper layers.
The crown line on a slab at Panorama Ridge measured roughly 2.4km.
40 to 70cm of settled storm snow since March 8th, with the most snow in the Bow Summit region, along the Wapta, and in Little Yoho. Strong S winds have formed slabs over sun crusts on steep S aspects or firm wind-affected snow elsewhere.
A persistent weak layer (Feb 22/Jan 30 facets) is buried 50-100 cm deep. In shallower eastern areas, the mid/lower snowpack is very weak with facets and depth hoar, while deeper western areas are more consolidated (see profiles below).
Another low-pressure system will impact the forecast region on Sunday, bringing 5 to 10 cm of snow accumulation. Ridgetop winds will increase to strong values from south west, and freezing levels will remain at the valley bottom.
