Avalanche Forecast

Archived

Mar 15th, 2023–Mar 16th, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

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

Be careful as you transition into wind affected terrain as newly formed windslabs have been reactive over the past 24hrs. Crusts on steeper solar aspect that formed on Wednesday will make skiing challenging.

Confidence

Moderate

Avalanche Summary

Natural avalanche activity has taperred over the past 24hrs with only a few isolated alpine windslabs on N and E aspects up to sz 2. These slabs were in steep unskiable terrain but ran into skiable terrain.

Snowpack Summary

The 30cm of recent snow is overlying a variety of different surfaces depending on aspect. On solar aspects it is overlying a 1cm thick melt freeze crust that formed from intense solar radiation. So far, field tests are showing that this snow is bonding well to this crust on these aspects. On polar aspects this new snow is overlying weak facetted crystals. On wednesday winds were moderate out of the SW and windslabs were quick to develop in this new snow. An avalanche cycle was triggered as a result of these winds with most natural activity occurring within the recent storm snow. Deeper in the snowpack (100-120cm) a layer of facets that developed in late January is producing hard sudden collapse compression test results. Even deeper than this layer are the weak basal facets and depth hoar. Thin spots as well as windloaded features should be treated as suspect and avoided at this time.

Weather Summary

Thursday will be a mix of sun and cloud with a light northwest wind blowing throughout the day. Morning temperatures will be around -19 but quickly warm up with the sun to around -3. The intense solar radiation is making solar aspects wet already so keep this in your mind as you travel. One model is calling for the freezing level to climb to 2000m by late afternoon. No new snow is expected.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Recent wind has varied in direction so watch for wind slabs on all aspects.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

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.