Avalanche Forecast

Issued: Jan 16th, 2013 4:00PM

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

A.L. Horton, Parks Canada

Jasper.

Direct solar radiation is not forecast, but should it occur, the avalanche danger will increase rapidly at all elevations.

Summary

Weather Forecast

Cloudy skies, strong NW winds and mild temperatures with freezing levels around 1400m on Thursday.Â No precipitation during the day but maybe up to 8 cm overnight Thursday.

Snowpack Summary

Snowpack remains thin and facetted at lower elevations, but is supportive above tree line. Last week's storm snow has buried a surface hoar layer (Jan6) down approx 30cm.Â Windslabs have formed on Southwesterly alpine aspects and previous significant snow transport by intense winds.

Avalanche Summary

Basal facet avalanches (both slab and loose) have been observed below treeline today.Â Yesterday, numerous size 2 and a few size 3 natural soft and hard slab avalanches were observed in the alpine.Â Many of these slides are stepping to ground and running to valley bottom.Â

Confidence

Freezing levels are uncertain on Thursday

Problems

Wind Slabs

Slabs have formed on a variety of aspects from moderate to strong winds (with extreme gusts). This condition is more prevalent with increasing elevation.

Avoid lee and cross-loaded terrain near ridge crests.Avoid convexities or areas with a thin or variable snowpack.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Deep Persistent Slabs

Surface instabilities such as loose snow and new windslabs may step down to ground, which means a small avalanche has the ability to become large very quickly. This will occur more likely in shallow snowpack areas.

Avoid shallow snowpack areas where triggering is more likely.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 3

Loose Dry

Wind and warming temperatures are triggering point releases, most commonly out of steep and rocky terrain.

The volume of sluffing could knock you over; choose your climb carefully and belay when exposed.Avoid ice climbs that are in terrain traps below large start zones.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 17th, 2013 4:00PM