Avalanche Forecast

Archived

Mar 14th, 2024–Mar 16th, 2024

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

Regions

Kananaskis, Bow Valley, Highwood Pass, North 40, Spray - KLakes, Ghost.

Dramatic warm up is forecast to occur this weekend with high freezing levels and warm temperatures. Warm temperatures will likely trigger another round of natural avalanche activity with the potential for full path avalanches. Good time to avoid avalanche terrain.

Confidence

High

Avalanche Summary

One new sz 3 on a south aspect north of Mt Nestor was observed on Thursday. This avalanche was likely triggered by a cornice collapse failing down to ground. A few smaller loose wet avalanches up to sz 1 were also observed.

Snowpack Summary

Warm temperatures are settling the upper snowpack and creating moist snow up to 2200m on all aspects and likely over 3000m on solar aspects. This new snow is settling and in some places overloading the weak layers triggering natural avalanches that are either failing on the ground or on the February crust down 70-100cm. Polar aspects in the alpine may still hold dry snow but windslabs should be expected if you are headed into this area. With our generally weak snowpack and the big pulse of heat that is coming this weekend, its a good time to avoid avalanche terrain in general. Avalanches have the potential to go full path reach all the way down to the valley floors. Cornices are large and looming over many features at this time of year and with the heat, they may act as a big trigger on underlying slopes.

GHOST FORECAST AREA

The Ghost area has more snow than usual. With this warming trend, pay close attention of what is above you. Wet loose avalanches and cornice failures are possible in this forecast region. Ice climbers should choose routes appropriately.

Weather Summary

Freezing levels are forecast to climb to 2500m on Friday with a mix of sun and cloud. Winds will be light and its hard to say how good the quality of the freeze will be overnight. Overall, The next few days will be a good time to avoid avalanche terrain.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Cornices become weak with daytime heating or solar exposure.
Extra caution for areas experiencing rapidly warming temperatures for the first time.
Remote triggering is a concern, watch out for adjacent and overhead slopes.
Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.