Regions
Banff Yoho Kootenay.
The skiing is excellent so enjoy it, but be patient and stick to moderate terrain until the Feb 10th layer has a chance heal. CJ
Weather Forecast
Clear skies and overnight temperatures in the -25'C range are forecast for tomorrow with highs around -13'C. Tuesday and Wednesday will see continued clear skies and a gradual warm up. Winds are forecast to be light from the NW.
Snowpack Summary
30-70cm of recent storm snow is sitting over the Feb10th layer of facets, sun crust and surface hoar. Field tests show an easy to moderate persistent shear at this interface. Recent SW winds have also created wind slabs in alpine terrain. These wind slabs are easily triggered and can step down to the Feb 10th interface.
Avalanche Summary
The natural avalanche cycle seems to have subsided, but a skier triggered avalanche (Class 2) was reported in the Lake Louise area today and a skier remote (Class 1.5) was reported in the Helen Lake area yesterday. Lots of evidence of the recent natural cycle on all aspects at treeline and above (up to Class 2.5) failing on the Feb 10th layer.
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.