Avalanche Forecast

Issued: Feb 13th, 2018 4:00PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Persistent Slabs and Wind Slabs.

grant statham, Parks Canada

Banff Yoho Kootenay.

Avalanche conditions continue to be very tricky. The snowpack is dangerous and avoiding avalanche terrain is important right now. Avalanches have been occurring in low angled terrain. Strong winds and 10-15cm overnight will keep the danger elevated.

Summary

Weather Forecast

A weather system is moving over the region for Tuesday night bringing very strong winds from the SW, along with potentially 10 cm of new snow. The snow and wind should taper off by morning on Wednesday morning with perhaps some clearing by the afternoon. Temperatures will remain cool, from -10 to -15.

Snowpack Summary

Strong winds have raked the snowpack creating widespread wind effect and hard windslabs at treeline and above. The upper half of the snowpack is a dense slab overlying three weak layers (Jan 16, Jan 6, & Dec 15) that are a mix of facets, crusts and surface hoar down 75-125cm in the snowpack. These layers have been producing very large avalanches.

Avalanche Summary

No new avalanches were observed or reported today - but we continue to observe large avalanches that occurred within the last few days. Today on Vermillion Peak we observed an avalanche on a low angled slope at treeline that appears to have been remotely triggered by skiers. We also saw evidence of a large avalanche on a gully wall below treeline.

Confidence

Problems

Persistent Slabs

A 100-125cm dense slab of January storm snow overlies three weak layers in the mid snowpack: Jan 16, Jan 6, and Dec 15. All are a mix of sun crust, surface hoar and facets depending on the aspect and elevation. These layers could easily be triggered.

Be wary of slopes that did not previously avalanche.Avoid all avalanche terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3.5

Wind Slabs

Strong winds on Tuesday evening has created widespread wind effect in most areas above treeline. Hard wind slabs are anticipated.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Feb 14th, 2018 4:00PM