Avalanche Forecast

Issued: Jan 19th, 2015 8:56AM

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

rbuhler, Avalanche Canada

South Rockies.

Lingering storm instabilities remain the primary concern. Give the new snow a couple days to settle and stabilize, especially in wind loaded areas.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

A ridge of high pressure should keep the region dry and mostly sunny for Tuesday through Thursday. Freezing levels are expected to reach around 1300m on Tuesday, 1000m on Wednesday, and climb to over 2000m on Thursday. Alpine winds should remain light for Tuesday and Wednesday but are forecast to increase to moderate on Thursday.

Avalanche Summary

On Sunday, several size 1 storm slabs and wind slabs were ski cut.Â A natural size 2 was reported in the Waterton area.Â Natural avalanche activity is generally not expected on Tuesday but remains possible in isolated areas. Human-triggering is possible or likely in wind loaded areas and steep terrain features, especially where surface hoar underlies the recent storm snow.

Snowpack Summary

10-30cm of new snow fell over the weekend.Â Fresh wind slabs have formed in lee features at alpine and isolated areas at treeline. The storm snow buried a layer of surface hoar and/or a crust that exists in many places up to 1900m. At higher elevations the new slow fell on widely wind affected surfaces. The mid-December crust layer is down 40-80cm.Â In many places this crust is overlaid by facets and/or surface hoar. In areas where the overlying slab is thick and cohesive, large avalanches remain possible on this interface. Closer to the ground a crust/facet interface that formed in November seems to be dormant for the time being.

Problems

Wind Slabs

Fresh wind slabs have formed in lee features. At treeline, pockets of wind slab maybe sitting on top of a layer of surface hoar.

Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

A persistent weakness down 40-80cm should remain on your radar as it has the potential to produce large avalanches.

Avoid convexities or areas with a thin or variable snowpack where triggering could be more likely.>Dig down to find and test weak layers before committing to a line.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Jan 20th, 2015 2:00PM