Avalanche Forecast

Issued: Jan 22nd, 2015 3:38PM

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

jon stuart-smith, Parks Canada

Waterton Lakes.

Very warm temperatures plus precipitation on Fri/Sat could increase avalanche danger. New wind slabs will develop and the potential for the Dec week layers to wake up is still a concern.

Summary

Weather Forecast

Up to 10cm is forecast for the divide starting Fri night. Temperatures will be warm with freezing level reaching ridgetop by Saturday. Strong West winds will continue for the next three days and accompany the precip on the weekend. This means continued windslab development and rise in avalanche danger.

Snowpack Summary

The little bit of snow from the weekend has been stripped from SW slopes by strong SW winds also built slabs on lee slopes. These are sitting on temp/sun crusts, old wind slabs or facets with surface hoar in sheltered locations. Surface slabs were very reactive in tests at Forum but shears 40cm down on pervious slabs failed with only hard results.

Avalanche Summary

There was evidence of wind slab avalanches at the back of Forum lake but this was likely from a few days ago. Otherwise there has been no avalanche activity observed up to Jan 22.

Confidence

Intensity of incoming weather systems is uncertain on Saturday

Problems

Wind Slabs

Windslabs up to 40cm thick are present on lee features at treeline and in the alpine but have started to settle. New slabs will be developing on Sat with strong West winds and will means windslabs will continue to be the main concern.

If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Use caution in lee areas. Recent wind loading have created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Persistent Slabs

We received additional snow load last weekend but have still not seen any evidence of activity on this layer in our area even though neighbouring areas have. Be mindful in thin snowpack areas, where the layer is more likely to be triggered.

Dig down to find and test weak layers before committing to a line.Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Jan 25th, 2015 4:00PM