Avalanche Forecast

Issued: Apr 20th, 2017 4:07PM

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.

grant statham, Parks Canada

Banff Yoho Kootenay.

We switched to "Spring Conditions" today 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

Friday looks like it will be a pretty nice day, with clear skies by the afternoon. Freezing levels will reach 2400m, and expect warm temperatures in the afternoon and in any sunny locations.

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.

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

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 21st, 2017 4:00PM