Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
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.
Confidence
High
Avalanche Summary
Avalanche accident today, 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.
Snowpack Summary
10-25cm in the past 48 hours and 30-90cm 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).
Weather Summary
A weak ridge will override the region Friday evening. Treeline temps will drop to -15C SW winds will be light to moderate in the alpine and skies will be mainly cloudy with a few flurries possible.
Cloudy Saturday with a few flurries, 3-10cm possible as a weak disturbance replaces the ridge. Treeline temperatures reaching -5C. Winds increase overnight to moderate. -10C at treeline .
Terrain and Travel Advice
- Make conservative terrain choices and avoid overhead hazard.
- Remote triggering is a big concern, be aware of the potential for wide propagations and large, destructive avalanches at all elevations.
Avalanche Problems
Persistent Slabs
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.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely - Very Likely
Expected Size: 2 - 3.5
Storm Slabs
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.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely - Very Likely
Expected Size: 1.5 - 3