Regions
Banff Yoho Kootenay.
Conditions will change very little Monday. Tuesday expect precipitation and wind. Danger ratings Tuesday and beyond will depend on actual snowfall amounts and wind transport. Stay tuned.
Weather Forecast
Cooler temps will remain on Monday. Expect to see cloud cover and very light accumulations of snow (trace). Up to 20cm is expected to arrive on Tuesday. Wind will also be increasing into the moderate range from the SW.
Snowpack Summary
Cooler temps this weekend will keep lower elevation melt free crusts intact. On solar aspects this crust is present to ridgetop. Small wind slabs found in the high alpine. Concern still exists for last weeks storm snow where it sits on a buried suncrust (down 20-30 cm) on south and west aspects. Shallow snowpack areas are also still a concern.
Avalanche Summary
An ice triggered avalanche on the highway path on Mt. Stephen buried the highway Saturday night. This large piece of ice did not trigger a slab, the ice mass and snow that it entrained created the volume of debris.
Confidence
Timing, track, or intensity of incoming weather system is uncertain on Tuesday
Problems
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.
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.