Avalanche Forecast

Archived

Feb 23rd, 2015–Feb 24th, 2015

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Kananaskis.

High northern aspects are the place to look for good snow at this point.

Confidence

Good

Weather Forecast

A cloudy day tomorrow should keep the solar aspects a bit cooler than today. An overnight low of -9 will refreeze today's suncrust. The alpine high will hit -4. Ridge winds will be light, and gusting to moderate from the west. Freezing level is expected to be 1700m. No precip is expected.

Avalanche Summary

A few isolated loose wet avalanches were noted today. All were about sz1.

Snowpack Summary

Valley bottom up to 2100 is still suffering from the Feb crust. There is 5-10cm's on top of it which is making upward travel easier . On the way down , the crust is breakable in many places and tricky skiing. At treeline the crust almost instantly turns to hard slab. These slabs were formed by a wind event last week. The density of these slabs ranges from very hard (hard to get an edge) to breakable. Beneath these new slabs are the older Jan 31st slabs, down 30-50cm's. The alpine has had considerable wind over the past week. In places the underlying layers have been blown clean. The windloading pattern is very easy to see right now. At all elevations, the sun had a huge impact today. A sun crust will be present on all south aspects and its thought to extend up to 2500m.

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.

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.