Daily forecasts begin Friday November 22nd. Until then, visit both the
South Rockies Blog and
Forecaster Blog at blogs.avalanche.ca for significant news, conditions updates & ideas on managing early season hazards.
Avalanche Summary
The most likely early season problem you’ll have to deal with involves wind and storm slabs that are poorly bonded to the underlying snow. These are most dangerous during and immediately after a storm and are most commonly found in alpine bowls and in the lee of ridgelines. The danger can last much longer where slabs of this season’s snow overlie old patches of snow from last year, on sit on top of glacial ice. The reason is that bonds between last year’s snow and this year’s are often quite poor. Temperatures will typically fluctuate at this time of year, often bouncing above and below freezing. If you get a rapid spell of warming, or worse, rain, immediately after a good dump of snow, there's a good chance of seeing an avalanche cycle. The consequences of being caught in an avalanche are heightened at this time of year, since trees, stumps and rocks litter runout zones. This is worth keeping in mind, as getting dragged through this kind of nastiness is definitely something to avoid.
Snowpack Summary
Successive early winter storms lead to a rapid buildup of the snowpack. Expect big changes to the snowpack structure with elevation, you might find full-on winter conditions in the Alpine and no coverage lower in the valleys. Here are some things to look for in the snowpack to help you identify potential avalanche danger. First, assess the quality of the slab. If the upper layers feel dense and show a tendency to crack or pull apart as a cohesive element, there’s a good chance conditions are primed for a slab avalanche. Watch the bowls below ridges and the gullies where there’s enough snow to slide. Second, try to identify areas where you might be riding over old snow from last year. These pockets often exist near the top of bowls, on the shaded side of steep gullies and under cliffs. Basically, they favour steep, high elevation north facing terrain. These pockets cause problems because the new snow from this year often bonds poorly to the old snow surface. This is particularly a problem where the new snow falls on steep glacial ice. Third, if you identify crusts within the snowpack, these can act as sliding layers, as well as promoting the growth of sugary facets above or below.