Avalanche Forecast

Issued: Apr 16th, 2017 4:00PM

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

A.L. Horton, Parks Canada

Jasper.

Weather forecasts have been steadily changing so best to plan your day based on the weather you see. Expect the hazard to rise with prolonged periods of sun or warm temperatures.

Summary

Weather Forecast

Cloudy and light flurries Monday and Tuesday with light SW winds and freezing level rising to 2000 m by mid-day.

Snowpack Summary

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 depending on air temp and solar input.

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 Sunday.

Confidence

Intensity of incoming weather systems is uncertain on Monday

Problems

Wind Slabs

SW winds has reactive alpine windslab on lee slopes just above tree-line. 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

Cornices

Rapid warming or intense solar will increase the likelihood of cornice failure. Cornices are becoming weak.

Avoid travel on slopes that are exposed to cornices overhead.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 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.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Apr 17th, 2017 4:00PM