Regions
Banff Yoho Kootenay.
Avalanche control is planned tomorrow during an afternoon warm spell. Mt's Bosworth, Stephen, Dennis, and the Vermilion Slide Paths will be affected. On this note, expect natural activity to spike on sunny slopes in the p.m.
Weather Forecast
A high pressure ridge is driving mild, dry air through the region. This, coupled with clear skies, will cause temp's to rise to near 0* Celsius in the alpine Saturday, especially in the southern portions of the region. Winds should be in the light to moderate range from the west. Sunday will be few degrees cooler with possible light flurries.
Snowpack Summary
Two main layers in the upper pack are Jan 23 and Jan 4 surface hoar/ facets or suncrust down 25 & 55. Watch for wind slabs in all open areas. These may be easily triggered in steep terrain.
Avalanche Summary
Very little activity. Minor point releases on south-facing aspects reported, all in the surface snow. Expect some natural activity from southerly aspects tomorrow afternoon.
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.
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.