Avalanche Forecast

Issued: Apr 15th, 2017 4:00PM

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

Deryl Kelly, Parks Canada

Jasper.

Weather forecasts have not been reliable in predicting snowfall and temps recently. Watch for, and carefully evaluate changes happening over the day.

Summary

Weather Forecast

Cloudy with clear periods and isolated flurries overnight, though really only a trace of new expected. Good cooling overnight. Wake up to scattered clouds and glorious sunshine with increasing clouds over the day. Light winds and freezing level rising at 2000m (roadside at Parkers or TL in the Bald hills).

Snowpack Summary

New windslab on open slopes above 2400m. Dryer surface snow on polar aspects over a solid mid-pack bridging the weak base above 2000m. The base is a combination of weak facets and depth hoar mixed around a Nov rain crust. A consistent melt-freeze cycle is occurring below tree line.

Avalanche Summary

Several large windslab avalanches around 2400 m on x-loaded gulley features and steep lee slopes observed south of Icefields on Friday. Nothing new reported or observed on Saturday.

Confidence

Intensity of incoming weather systems is uncertain

Problems

Wind Slabs

Mod SW winds has reactive alpine windslab on lee slopes. If triggered, these could step down to the deep persistent slab resulting in very large avalanches.

Minimize overhead exposure during periods of heavy loading from new snow, wind.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Deep Persistent Slabs

The deep instability could be triggered by large loads such as a cornice failure or a surface avalanche. 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

Unlikely - Possible

Expected Size

2 - 4

Cornices

Rapid warming in temperature or intense solar will increase the likelihood of cornice failure.

Avoid travel on slopes that are exposed to cornices overhead.

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

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