Avalanche Forecast

Issued: Apr 3rd, 2017 4:00PM

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

mark herbison, Parks Canada

Jasper.

Daytime and solar heating will weaken cornices, avoid traveling in avalanche terrain during periods of intense solar input.

Summary

Weather Forecast

Clear skies with no forecasted snow as a shallow ridge of high pressure moves into our area on Tuesday. Winds will be light from the West with an alpine high of -6 with freezing levels rising to 1500m. Light flurries on Wednesday into Thursday with freezing levels to 2000m.

Snowpack Summary

10cm of new snow in past 2 days has formed windslab along lee ridge-lines and cross-loaded gully features from SW winds. Mid-pack bridging basal weakness. Entire lower snowpack is weak with a combination of facets, Nov rain crust and depth hoar. Below tree line a 5-10cm melt freeze crust sits above a moist facet layer to ground.

Avalanche Summary

No new avalanche observations on Monday, but previous cornice and windslab failures have triggered the deep persistent slab resulting large full path avalanches. Loose wet avalanches have previously occurred on steep south and west aspect below tree-line.

Confidence

Timing or intensity of solar radiation is uncertain on Tuesday

Problems

Loose Wet

Prolonged solar radiation and rising freezing levels with weaken the snowpack on South and West aspects, especially around steep and rocky areas.

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Cornices

Cornice failure is hard to predict but is more likely with inputs like solar radiation and wind-loading.

Give cornices a wide berth when travelling on or below ridges.Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 3

Deep Persistent Slabs

This problem is unlikely to disappear. It can be triggered by large loads like cornice fall or windslab failure. Human triggering is most likely from shallow spots or on steep unsupported slopes.

Be cautious in shallow snowpack areas where triggering is more likely.Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 4

Valid until: Apr 4th, 2017 4:00PM