Avalanche Forecast

Issued: Apr 19th, 2014 4:00PM

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

snow safety, Parks Canada

Banff Yoho Kootenay.

Hazard is subject to rapid change based on the duration and intensity of the sun over the day. Start early, get up high for the best skiing and get back early. DK

Summary

Weather Forecast

Expect a mixed bag of light convective snow, sun and gusty west winds. Alpine temps are expected to remain cool and freezing level to 1800ms. A good overnight freeze should make travel easy in early morning but expect any solar aspects to soften up quickly if the sun gets to them.

Snowpack Summary

HST settling and a surface crust will exist in the am and break down over the day on all aspects up to to 1800ms, higher on S and W aspects. Cornices seem to be more sensitive to the temperature fluctuations especially on the solar aspects and have been seen to trigger slabs below both in the storm snow and the deeper persistent layers.

Avalanche Summary

Control work on Sat on a solar aspect produced storm slabs up to sz 2 in the alp and a loose wet, aggressive size 2 below treeline. Natural cornice release in the alpine triggered the slope below to sz 2 and it appears they have become far more sensitive. Forecasters remain cautious about the deep basal layer being triggered from shallow areas.

Confidence

Problems

Loose Wet

Subject to the duration and intensity of the sun. Areas near and around rocks will break down quick and steeper areas have real potential to move and build volume quickly.

Start and finish early before the surface crusts melt.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Cornices

Cornices appear to be more sensitive to temperature fluctuations. They are just so unpredictable that it would be prudent to give them a wide berth.

Cornices become weak with daytime heating, so travel early on exposed slopes.Give cornices a wide berth when travelling on or below ridges.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Deep Persistent Slabs

This layer is just so unpredictable. Super stubborn, but terrible consequences if you trigger it; most likely from a shallow rocky location.

Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Apr 20th, 2014 4:00PM