Avalanche Forecast

Issued: Dec 16th, 2012 6:14PM

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

tim haggarty, Parks Canada

Waterton Lakes.

Snow in the forecast coupled with strong winds and warming. Watch for slab formation at all elevations. Great skiing above 1900m but use of the summer trails is still a good idea down low.

Summary

Weather Forecast

A low pressure system is currently producing moderate snowfall which is forecast to continue through Monday. Strong W and SW winds and warmer temperatures should appear as well. Tuesday looks drier and much cooler with some clearing and winds easing a bit and shifting to the NW. Another system may bring more snow, warming, and wind on Wed.

Snowpack Summary

5 to 10 cm new snow. At and above treeline, Moderate West winds creating 20-30 cm soft slabs that sit on more widespread hardslabs. S and W slopes are predominantly scoured with crossloaded features. Below 1900m the snowpack is dominated by 4 crust layers. Above 2000m only the basal Nov 6 crust exists as a moist layer of melt freeze crystals.

Avalanche Summary

Heard one avalanche that likely came out of extreme terrain at the back of the Cameron Lake area. Only surface sloughing observed today with ski cutting but we stayed in conservative terrain. Many start zones look to be quite loaded and waiting for a trigger...

Confidence

Intensity of incoming weather systems is uncertain on Monday

Problems

Wind Slabs

Moderate W winds and new snow are developing 10-30cm thick soft slabs over previously widespread hard slabs. Step out of the track and get a feel for the density of the snow you are traveling in. Use your poles to feel for buried slabs.

Caution in lee and cross-loaded terrain near ridge crests.The recent snow may now be hiding windslabs that were easily visible before the snow fell.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Storm Slabs

A rain crust that went as high as 1950m now has 30 -50 cm on it. Cold temperatures have not helped the bond with the new snow. With the forecast warming, wind, and precip, a firmer slab will likely develop which could become reactive to skier traffic

Be alert to conditions that change with elevation.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 1

Valid until: Dec 19th, 2012 4:00PM