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Avalanche Forecast

Archived

Jan 12th, 2022–Jan 13th, 2022

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

Banff Yoho Kootenay.

High freezing levels and lots of wind have created tricky conditions. The surface snow is dense and the persistent slab problem appears to be activating in new ways across the region. Note some new patterns in avalanche activity are emerging.

Weather Forecast

The strong southwesterly flow continues for the next 24-hours with strong winds, freezing levels to 2000 m and another 10-20 cm of snow (rain low elevations). This changes at the end of the day Thursday following a cold front, when a ridge of high pressure builds, the skies clear and the temperatures drop by 10 degrees.

Snowpack Summary

Warm temperatures, winds, 10 cm of snow and light rain to ~2000 m have created dense windslabs that overlie facets from the Xmas cold snap and produce moderate test results. At lower elevations the middle of the snowpack is facetted and combined with the Dec 2 layer in Kootenay is now becoming active. This will continue through Thursday.

Avalanche Summary

A new pattern is emerging. SSV had a skier controlled size 2.5 starting at 2500m with a windslab over facets. It ran full path and dug deeper into facets low in the path. Lake Louise had repeated windslabs from alpine terrain that pulled deeper slabs on facets at the lower elevations. Skier accidental size 2 below TL ran full path at LL today also.

Confidence

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.