Avalanche Forecast

Issued: Apr 17th, 2017 4:00PM

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

Mark Herbison, Parks Canada

Jasper.

Possibility of rain at lower elevations will increase the avalanche hazard below tree line.

Summary

Weather Forecast

Cloudy with 5-10cm of snow by Wednesday morning. Freezing level rising to 2000m with an alpine high of -3 and light southwest winds.

Snowpack Summary

Windslab building on lee alpine ridge lines. Melt freeze crust up to 2000m. Dryer surface snow on northerly aspects over a solid mid-pack bridging the weak base above 2000m. The bottom of the snowpack consists of weak facets and depth hoar mixed around the Nov rain crust.

Avalanche Summary

No new avalanches observed or reported.

Confidence

Forecast snowfall amounts are uncertain on Tuesday

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 large avalanches.

Minimize overhead exposure during periods of heavy loading from new snow, wind.Use caution in lee areas. Recent wind loading has created wind slabs.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Cornices

There are some very large cornices out there, give them a wide berth. Cornice failure is hard to predict but is more likely with inputs like solar radiation, high freezing levels and wind-loading.

Avoid travel on slopes that are exposed to cornices overhead.Give cornices a wide berth when travelling on or below ridges.

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

Elevations: Alpine.

Likelihood

Unlikely - 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.

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

Valid until: Apr 18th, 2017 4:00PM