Avalanche Forecast

Issued: Dec 8th, 2014 4:11PM

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

tim haggarty, Parks Canada

Waterton Lakes.

Warming will cause some deterioration in both the snowpack and travel conditions especially for Wednesday. Below treeline travel off of trails is not recommended due to poor coverage.

Summary

Weather Forecast

The freezing level is expected to continue rising Tuesday reaching near mountain top with about 10mm of rain forecast. Freezing levels look to return to Little Prairie Wed and hopefully the 10mm of precip forecast for Wed night arrives as snow.

Snowpack Summary

Suncrusts forming steep South slopes. Wind effect found in open areas treeline and above. Mid-Nov facets sit on 30cm of crusts formed early in November at treeline and above. Below 2200m, rain at the start of the storm on Nov 26 created a crust over the facets or melted them. The slab above these layers grows with elevation from 30 to 100 cm.

Avalanche Summary

There is some small solar activity occurring on steep solar slopes especially around black bodies. It is easy to trigger wind slabs in specific locations. We continue to find further evidence of the widespread cycle on November 28 but have seen no recent activity on these layers.

Confidence

Due to the number and quality of field observations

Problems

Wind Slabs

Thin windslabs can now be found at treeline. This slabs are thin and very localized and are easy to stumble into as they appear mid slope in front of you. With the warmer temps expected these slabs may become more sensitive before they improve.

Use caution in lee areas. Recent wind loading have created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

These slabs taper radically with elevation and are sitting on a thick crust. Large slides resulted from failures in the recent storm snow over the crust that extends to around 2300m. These slabs may become easier to trigger with the expected heating.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Deep Persistent Slabs

At high elevations cooler temps have only allowed thin crusts to form above the weak November Facets which may remain a possibility for triggering for some time. Use caution TL and above especially in thin or variable areas.

Avoid thin, rocky or sparsely-treed slopes.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Dec 11th, 2014 4:00PM