Avalanche Forecast

Issued: Dec 17th, 2014 4:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Deep Persistent Slabs.

Lisa Paulson, Parks Canada

Banff Yoho Kootenay.

We are in a classic Rockies snowpack. Thin and rocky with a basal weakness. Forecasters have low confidence in any steeper terrain above tree line. Keep this in mind when choosing terrain to ride!

Summary

Weather Forecast

Cool temperatures, light winds and minimal precipitation are the short term forecast. Cloud cover will increase Thursday/ Friday and we might get a few snowflakes. A mild inversion is making alpine temperatures more comfortable, but doing little to destabilize the snowpack.

Snowpack Summary

In the alpine a few cm`s of new snow overlies a firm base of old wind slabs. At treeline and above, mild temperatures have helped strengthen the upper snowpack but the basal rain crust/facets remain weak. Below treeline a rain crust is present and the snowpack is solidly frozen in most areas.

Avalanche Summary

There were many ski tracks going into more aggressive alpine terrain in the Bow Summit area recently. A large size 2.5 natural avalanche was also noticed on a NW aspect of Observation subpeak. This looked to be recent within the last 3 days and is indicative of the low probability/ high consequence conditions we are currently dealing with.

Confidence

Due to the number of field observations

Problems

Deep Persistent Slabs

Natural avalanche activity has tapered off but snowpack tests show that the weak facets at the base of the snowpack continue to be a concern. With a stronger upper snowpack, triggering an avalanche is less likely but the consequences remain serious.

Be aware of thin areas that may propogate to deeper instabilites.Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Dec 18th, 2014 4:00PM