Avalanche Forecast

Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Monday night: Increasing cloud coverage, trace of new snow, moderate southwest wind, treeline low around -5 °C, freezing level below valley bottom.

Tuesday: Cloudy, 5-10 cm new snow, moderate to strong southwest wind, treeline high around -1 °C, freezing level rising to 1300 m.

Wednesday: Cloudy, 10-20 cm new snow and rain at lower elevations, moderate southwest wind, treeline high around +2 °C, freezing level rising to 1900 m.

Thursday: Mostly sunny, up to 5 cm new snow, light to moderate southwest wind, treeline high around +4 °C, freezing level rising to 2300 m.

On Sunday, a few natural cornice failures resulting in size 2.5 avalanches were observed as well as a natural size 2 slab avalanche. 

On Saturday, storm slab avalanches up to size 2.5 were triggered by explosives. Overnight, a large (size 3.5) natural storm slab avalanche released and a large (size 2.5) cornice failure occurred. 

On Friday, storm slab avalanches released naturally up to size 2.5. Explosives triggered storm slabs to size 2.5, and skiers triggered avalanches to size 2. A large (size 2) natural cornice failure was reported likely having failed in the overnight storm.

The persistent slab problem has produced sporadic and spotty activity in the Lizard-Flathead and nearby regions. 

• On Monday, a large size 3 deep persistent slab released naturally in the neighbouring Waterton National Park. The avalanche was more than 2 m deep.
• On Sunday, a very large (size 4) persistent slab avalanche that released naturally in the neighbouring Waterton National Park was observed. The avalanche released at an elevation of 2000 m on an E-NE aspect.
• Last Wednesday, two size 3 persistent slab avalanches were reported. They released at an elevation of 1800 m and 2000 m on an E aspect and were 2 m deep. Most likely they released during the storm before the New Year. 
• Last week on Sunday, a size 2.5 persistent slab avalanche was triggered on an E aspect at treeline. This avalanche is detailed in a MIN post and features in our latest blog post, Photos of recent persistent slab avalanches in the southern interior.

The recent storm snow totals 40-50 cm. In open terrain and upper elevations, wind developed more reactive deposits around lee and convex features. This recent snow covered a hard, faceted snow surface which formed during cold temperatures and may take a little time to bond. 

The most notable layer of concern in the snowpack is a crust that was formed in early December and is now down 100-270 cm. Activity on this layer has been sporadic, the most recent persistent slab avalanche in the region was reported on January 2. This layer has created a low likelihood, high consequence scenario which is best managed through conservative terrain choices and disciplined backcountry travel techniques.

• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
• Be aware of the potential for large avalanches due to the presence of a persistent slab.
• Avoid shallow, rocky areas where the snowpack transitions from thick to thin.