Avalanche Forecast

Archived

Mar 22nd, 2024–Mar 23rd, 2024

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.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

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

Recent snow which is up to 55cm in some places is quickly settling and forming storm slabs. Be sure to evaluate the bond with the new snow and the newly formed March 20th crust. Snow was also moist by 1100am on Friday on solar aspects so pay attention to the solar input and be preparred to adjust you trip based on decreasing stability caused by the sun or warm temperatures.

Confidence

High

Avalanche Summary

Several loose dry avalanches up to sz 1.5 were observed from steep alpine faces. One new Sz 2 slab was also seen on a SE aspect at treeline failing down 50cm. This slab covered tracks on the common exit from the Tryst Lake area. The slope was steep (>40deg) and a cross loaded feature.

Snowpack Summary

30-60cm of recent low density snow has fallen under the influence of the up slope and convective storms moving through the region. This snow has seen very little affect from the wind but a few storm slabs were noted in treeline wind affected features failing down 50cm. This new snow is overlying the March Temperature crust that is found on all aspects except high pure north alpine areas. So far, the bond with the new snow and the underlying crust is good. Deeper in the snowpack the February 3rd crust still exists but avalanche activity on this layer has decreased since the warm temps last week settling out the snowpack. It is still worth digging and poking down to evaluate this layer. On Friday, when the sun came out it rapidly settled the new snow making it moist within the top 15cm. As it refreezes, lower elevation terrain as well as solar aspects are likely to have a temperature crust.

Weather Summary

Light snow is forecast to continue with accumulations around 5cm. Winds will continue to be light out of the NW and skies will generally be a mix of sun and cloud. Temperatures will be -12C overnight warming up to -8C by midday.

Be aware that when the sun does come out it packs a punch at this time of year and quickly snow stability will deteriorate on the solar aspects. Thin cloud can also lead to a "Greenhouse effect" that can also make the upper snowpack moist and unstable. Lots going on in Spring!

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Conditions may have improved, but be mindful that deep instabilities are still present.
Fresh wind slabs will likely form throughout the day, diligently watch for changing conditions.
The more the snowpack warms-up and weakens, the more conservative you`ll want to be with your terrain selection.

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.

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.

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.