Avalanche Forecast

Issued: May 15th, 2014 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.

conrad janzen, Parks Canada

Banff Yoho Kootenay.

This is the last regular bulletin. We will update it if there are significant changes. For specific condition information during spring and summer, see Parks Mountain Safety, the Mountain Condition Reports or contact Visitor Safety at 403-762-1470.

Summary

Weather Forecast

A light freeze Friday morning, then a mix ofÂ sun and cloud with freezing levels up to mountain top by Friday afternoon. Saturday through Monday we expect rain at lower elevations with wet snow in the alpine and precipitation accumulations between 30-45mm. Daytime freezing levels are forecast between 2500m and 3200m with little recovery overnight.

Snowpack Summary

Spring conditions now exist. After cool clear nights a firm melt freeze crust is present which deteriorates with daytime heating. Below 2000m the snowpack is mostly isothermal. Above 2000m the snowpack is generally supportive with the surface becoming moist with daytime heating. Weak basal facets are still present in many locations.

Avalanche Summary

The last week has seen lots of loose wet slides at lower elevations and on steep solar aspects up to size 2.5 with daytime heating. Several cornice failures have also been observed. No recent slab avalanches have been observed however with any sustained warming or major rain events we expect to see increased avalanche activity on the basal facets.

Confidence

Problems

Loose Wet

Intense sun, daytime heating or high overnight freezing levels will result in loose wet avalanches out of steep terrain. Start trips early and plan to be out of avalanche terrain before things heat up.

Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. Travel early before the heat of the day, and avoid big slopes in the afternoon.

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Cornices

With warm temperatures cornices will become weak and fail. Minimize your exposure to cornices and keep a close eye on the temperatures and solar effect on the slopes above you.

Cornices become weak with daytime heating, so travel early on exposed slopes.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

The basal facets have not been a problem for some time however with any sustained periods of warm temperatures or intense rain or wet snow events we may see large wet slabs failing on this layer.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: May 16th, 2014 4:00PM