Avalanche Forecast

Issued: Jan 24th, 2014 7:32AM

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

jon stuart-smith, Parks Canada

Waterton Lakes.

Warmer temperatures and solar radiation will increase the avalanche danger for the weekend. Variability in snowpack depth and the potential for triggering a large avalanche on the deep persistent layers mean routes should be chosen conservatively.

Summary

Weather Forecast

A ridge of high pressure will continue to dominate with mainly clear skies and dry conditions until Sun. An inversion is forecast for Fri and Sat which could bump temperatures above freezing in the alpine. Winds in the valley bottom could be strong but are forecast to be mainly light W/NW at ridgetop. Sun will be cooler and with a few flurries.

Snowpack Summary

10cm of snow arrived Wed with no wind . Under this is sun crusts on SE-SW slopes, wind effected surfaces in any open area, or faceted snow or surface hoar on sheltered areas. 30 to 40 cm above the ground weak, facetted snow remains a concern on steep or unsupported planar slopes and in the thin areas found with this highly variable snowpack.

Avalanche Summary

There has been very little avalanche activity observed in the Park in the last week. Although avalanche activity may decline in this stable period, remember that this problem will be with us for some time to come

Confidence

Timing or intensity of solar radiation is uncertain

Problems

Wind Slabs

The snow from Wednesday is starting to build new windslabs. These will be touchy for the next few days until the begin to settle. Previous windslabs are also a concern underneath this new snow. These could be triggered from the many thin areas.

Be aware of the potential for wide propagations due to the presence of hard windslabs.Be careful with wind loaded pockets. Be aware of wide variation in snowpack depth

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

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

Be conservative with your terrain selection and assess steep or unsupported planar slopes carefully. The new snow may be hiding shallow areas where triggering may be more likely and with the variability in snowpack there are many thin areas.

Make observations and assess conditions continually as you travel.Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely

Expected Size

2 - 3

Cornices

Temperature inversion with warmer air at ridgetop and strong solar radiation will weaken snow in steep rocky areas. A falling cornice could create the large load needed to trigger a deep persistent slab so be conscious of what is overhead.

Pay attention to overhead hazards like cornices.Cornices become weak with daytime heating.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

2 - 3

Valid until: Jan 26th, 2014 4:00PM