Avalanche Forecast

Issued: May 15th, 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, Wet Slabs and Cornices.

ian jackson, Parks Canada

Banff Yoho Kootenay.

This is the last scheduled avalanche bulletin for the season. Above average snowpack at high elevations means we should have an extended spring ski season! Check out the Mountain Conditions Report weekly regional summaries for up to date conditions.

Summary

Weather Forecast

Some helpful weather links:Remote weather stations in Banff, Yoho & Kootenay - Real time, raw, actual weather data.Avalanche Canada Mountain Weather Forecast - Good for getting an overview of the major weather systems.SpotWx - Good for a localized forecastEnvironment Canada Yoho forecast - Simplified valley bottom forecast for Lake Louise area.

Snowpack Summary

Isothermal snow exists at lower elevations. Crusts formed during clear cool nights will break down quickly with solar inputs. Expect moist surface snow to mountain top in the afternoon with the exception of high elevation North slopes. The basal facet weakness persists at treeline and above and is reactive to large triggers or warm temperatures.

Avalanche Summary

In general, avalanche hazard will be greatest during hot sunny days or warm rain. This has the potential to trigger smaller loose wet avalanches and larger wet slab avalanches on the basal weak layer. For current avalanche activity and observations, check out the Mountain Conditions Report

Confidence

Problems

Loose Wet

Loose wet avalanches are occurring on all aspects and elevations during the warmest parts of the day, especially when the sun comes out. Some of these are also triggering wet slabs. Plan your trip to be out of any big terrain before things heat up!

Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Wet Slabs

Wet slab avalanche activity will taper off with cooling and increase during hot periods of the day, with large triggers like cornices or when there is no overnight refreeze. The deep facets will remain a problem through the spring season.

Travel early before the heat of the day melts surface crusts, and avoid big slopes in the afternoon.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 4

Cornices

Cornices have taken quite a hit with the recent heat. Many are cracked and slowly peeling off of ridges. These should be considered suspect as they will likely fail in the coming weeks.

Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.Cornices become weak with daytime heating, so travel early on exposed slopes.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: May 16th, 2017 4:00PM