Avalanche Forecast

Issued: Apr 21st, 2017 4:00PM

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

snow safety, Parks Canada

Banff Yoho Kootenay.

We have switched to "Spring Conditions" and will no longer issue danger ratings. The snowpack is so variable through the day. The key this time of year is to start early (first light) and be done by noon.

Summary

Weather Forecast

A good overnight freeze is forecast for Saturday AM with freezing levels rising to 2400-2500m by the afternoon, a mix of sun and cloud, and light winds.Â

Snowpack Summary

The snowpack is a real mixed bag right now: totally dependent on aspect and elevation. At treeline and above, melt freeze crusts exist to ridge top on solar aspects, while on north aspects, dry surface snow still exists above ~2200m. Below treeline the snowpack becomes wet through the day. The snowpack is slowly changing to a spring snowpack.

Avalanche Summary

No new avalanches reported or observed today.

Confidence

Problems

Loose Wet

Afternoon warming will create loose wet problems at low elevations and on S and W facing terrain at higher elevations.

Pay attention to sluffing off cliffs and steep solar terrain, signs of a warming snowpack.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Cornices

Cornices continue to fail. Minimize your time underneath these and remember that a cornice failure could also trigger the deep persistent slab on the basal facets.

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.

Likelihood

Possible - Likely

Expected Size

1 - 3

Deep Persistent Slabs

The snowpack is gaining strength, but the weak basal facets continue to produce sudden collapse results and can produce large avalanches with large triggers. Stick to planar, supported slopes with a deeper snowpack if entering steep terrain.

Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Apr 22nd, 2017 4:00PM