Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural avalanches possible, human triggered probable.
Regions
Banff Yoho Kootenay.
Expect the avalanche danger to increase this weekend. Slopes with a thin and variable snowpack will be the most susceptible to human triggering. SH
Weather Forecast
Strong to Extreme Westerly winds in the alpine starting Friday evening through to the end of the weekend. A system will enter the region on Saturday afternoon with current forecasts calling for roughly 25-40cm by Monday. Alpine temperatures will stay in -8 to -12 C range, and freezing levels will be at valley bottom.
Snowpack Summary
West winds have created widespread wind effect in the ALP and at TL. Below 1500m a rain crust exists. The Feb.10th layer is down 50-110 and is reactive with large whumphs and sudden collapse results in thin snowpack areas, and hard results observed in thick snowpack areas.
Avalanche Summary
No new avalanche activity noted today. Yesterday there was still extensive whumpfing on Helen Shoulder which was a thin snowpack with a buried sun crust (E side of divide). We are still only just coming out of a major avalanche cycle.
Confidence
Forecast snowfall amounts are uncertain on Sunday
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.