Regions
Banff Yoho Kootenay.
The new snow has made for excellent ski conditions. A storm is approaching on Thursday that will raise the hazard if it materializes as forecast.
Weather Forecast
Light north winds and cold temperatures overnight (-20's). Wednesday looks like a nice day with alpine winds increasing to moderate from the west. The next system will be coming in mid-day on Thursday and we should see 30-50 cm with rising freezing levels to 1800m and increased winds from the SW.
Snowpack Summary
20-25 cm low density snow now sits on the Jan 30th crust. SW winds picked up overnight and created windslabs at higher elevations and in typically wind exposed areas. These are mostly small and confined to immediate lees. The very weak base of depth hoar continues to dominate the region, with moderate compression tests 25 cm above the ground.
Avalanche Summary
A large natural occurred on Mt. Stephen sometime in the last 24 hours. This was likely due to localized wind loading in the area overnight. There is a lot of low density snow available for transport so conditions can change quickly if wind is present.
Confidence
Intensity of incoming weather systems is uncertain on Thursday
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.
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.