Regions
Banff Yoho Kootenay.
Excellent skiing conditions. We are more concerned with the Feb.10th/basal layers in thin snowpack areas (mainly E of the divide) than the deeper snowpack regions (mainly W of the divide.)
Weather Forecast
15cm is expected in the Bow Summit area, 10 in Lake Louise and Sunshine areas on Sunday. Winds will be light gusting moderate and temperatures will be cool in the alpine and will go above freezing in the valley bottoms. On Mon and Tues, clearing skies and light winds may raise the hazard on solar aspects in the afternoon.
Snowpack Summary
Up to 47cm HST, generally bonding well with more wind effect today in alpine areas. In shallow, weaker snowpack areas, the basal facets and Feb10 layers are still reactive in field tests. In deeper, uniform areas these problems are less of a concern. On S aspects there are a few buried suncrusts. Moist snow below 1600m today in Yoho on all aspects.
Avalanche Summary
On a flight E of the Lake Louise ski area today, numerous avalanches were observed in alpine areas mainly on E and SE aspects within the last 24-36 hours. These appeared to be either in the recent HST or on a deeper layer, likely the Feb.10th. A skier accidental sz 1-1.5 was also reported in the Lipalians today which went to ground (80cm).
Confidence
Freezing levels are uncertain on Monday
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.