Avalanche Forecast

Issued: Jan 14th, 2017 4:00PM

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

stephen holeczi, Parks Canada

Banff Yoho Kootenay.

Some instances of cornices acting as the trigger for wind slabs and deeper releases. Warmer temperatures for Sunday. Watch for areas where wind slabs sit over the rotten facet layers that make up the bottom half of the snowpack. SH

Summary

Weather Forecast

Alpine temperatures between -12 and -8 C for Sunday and light gusting moderate Westerly winds. Eastern regions could see valley bottom afternoon highs in the -3C range. Some minor snow is currently forecast starting Monday night.

Snowpack Summary

Lots of hard wind slabs at treeline and above from a variety of wind directions over the past while, most notably N winds from the arctic air. This has produced a reverse loading pattern in many locations. These hard slabs in many starting zone areas overly a weak, faceted snowpack with numerous instabilities in the lower half of the snowpack.

Avalanche Summary

There was a cornice triggered size 2.5 off of a SE aspect at 2800m on Cascade Mountain Friday afternoon. It was hard to tell the bed surface but looked to be over a meter deep. Another size 2.5 with explosives on an ESE aspect to ground at Sunshine. Other similar avalanches initiated by large triggers have been noted over the last few days.

Confidence

Problems

Wind Slabs

Winds from the north have created hard wind slabs in many areas, and these are reverse from normal locations. These are becoming harder to initiate, and will likely not be a problem in a few days time.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Deep Persistent Slabs

The lower half of the snowpack is garbage, and will be for the distant future. Facets, crusts and depth hoar make for a very unsupported base of the snowpack. These are also harder to initiate, but will cause a large avalanche if triggered.

Be aware of the potential for wide propagations.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Jan 15th, 2017 4:00PM