Avalanche Forecast

Issued: Apr 14th, 2017 4:00PM

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

a.l. horton, Parks Canada

Jasper.

Plan your day to avoid slopes with overhead hazards such as cornices and/or windslabs. The new snow and wind in the forecast will make these more sensitive and large loads can trigger the deep persistent slab that is widespread in the forecast area.

Summary

Weather Forecast

15 cm of snow expected by Saturday evening with moderate SW winds. Freezing level peaking at 1700 m on Saturday. Sun and warming temperatures coming on Sunday.

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.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Saturday

Problems

Wind Slabs

15 cm of new snow with moderate SW winds will create 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.

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

Cornices

New snow and wind 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 15th, 2017 4:00PM