Avalanche Forecast

Issued: Jan 17th, 2014 9:01AM

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

jon stuart-smith, Parks Canada

Waterton Lakes.

Both wind slabs and cornices will become more sensitive to failure with heating. These events could provide the large load necessary to trigger a deep persistent slab. Be conservative with your terrain selection this weekend.

Summary

Weather Forecast

Temperatures in the valley bottoms are forecast to go into the teens for weekend and above zero into the foreseeable future. Conditions will remain dry and windy. Freezing levels are expected to reach mountaintop for a sustained period on Saturday. With these temperatures, solar radiation will have a profound effect on the steep solar aspects.

Snowpack Summary

Thursdays warmth and sun has created a crust on any steep south facing. Recent strong and turbulent West winds have created wind slabs in the lee of exposed features but even downslope from ridgetops, at all elevations. 30 to 40 cm above the ground weak, facetted snow remains a concern on steep or unsupported planar slopes especially in thin areas.

Avalanche Summary

There was some avalanche activity associated with the wind and storm slabs over the last few days. Thursday the warm temperatures were starting to cause snowballing out of rocky areas on steep southeast facing slopes.

Confidence

The weather pattern is stable

Problems

Wind Slabs

Strong west winds have created windslabs on lee slopes below ridgelines. These slabs can be found well down from the ridgetop and into open areas due to the intensity of the wind. Warm temperatures will increase the likelihood of triggering.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.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

Snowpack depth is highly variable. It might be hard to spot the shallow areas where triggering this deeply buried weak snow is more likely. Large loads such as falling cornices or surface avalanches also have the potential to wake up these slabs

Avoid shallow snowpack areas where triggering is more likely.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

Warm temperatures and sun will weaken the large cornices that developed from the snow and wind from last week. These could be the large load required to trigger the deeper instabilities in the snowpack and create large avalanches.

Extra caution needed around cornices with current conditions.Minimize exposure to overhead avalanche terrain, large avalanches may reach run out zones.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Jan 19th, 2014 4:00PM