Regions
Banff Yoho Kootenay.
The overall snowpack is slowly improving, but Thursday should see a short-term burst of windslab action as the 25cm of fluff on the ground will be blown around by strong winds in the alpine (>70 km/hr). Caution in immediate leeward areas.
Weather Forecast
The upper level flow puts our region back in the storm track, and a series of minor storms will cross the region over the next few days. Most of the punch will be to the west, but expect 5 cm on Thursday with strong alpine winds developing through the day. Temps at treeline will remain steady at -4 to -10 all week.
Snowpack Summary
10-25cm of low density snow has fallen in the last four days, with minimal wind effect except in alpine areas. This snow overlies suncrust and a firm surface, and seems to bonding well. The main concern is the deep facets throughout the region which present a long-term problem. Total snow depth is the most important factor; deep snow = strong snow.
Avalanche Summary
Only sluffing in very steep terrain was observed today (cliffs, steep gullies, etc).
Confidence
Wind speed and direction is uncertain on Thursday
Problems
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.
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.