Regions
Banff Yoho Kootenay.
It is still very much winter up high. Storm snow and steady wind over the weekend has created wind-slabs in the alpine. Step back from skiing exposed and committing lines in the alpine until the wind-slabs have settled out.
Weather Forecast
Temperatures will remain relatively cool (-5 to -10), even in the valley (4 to -5), for the next few days. Snowfall is supposed to taper off. Convective flurries in localized areas will still be occurring however. The wind will subside to the light range (SW) today and stay there for 48 hours or so.
Snowpack Summary
20 to 50cm has fallen at higher elevations since April 9. The new snow and wind is creating windslabs on lee N and E aspects, some up to 100cm deep in immediate lees in the alpine. Facets 50 to 70cm deep produce hard shears but have not produced an avalanche for a while.
Avalanche Summary
A few small windslabs (size 1) were noted in isolated areas throughout the park today, however visibility was limited. Additionally several dry loose avalanches were observed in steep terrain in the alpine to size 1.
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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.
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.