Avalanche Forecast

Archived

Dec 9th, 2023–Dec 10th, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

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.

Regions

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

We are still in the human triggering phase of this storm cycle. Tread lightly as you approach windy areas.

Confidence

Moderate

Avalanche Summary

Numerous loose dry avalanches today out of very steep, rocky terrain. Most were modest size 2's and didn't travel very far.

More notably, a couple of wind slab avalanches were seen today. Again. east aspects and on slopes below major cliffs. Wide propagations were noted with sizes up to 2.

Snowpack Summary

We keep skipping around the region trying to get a handle on the distribution and character of our new and improved snowpack. Today took us to the lower Tent Ridge area. Similar to the east side of the road, snow depths are less than other areas. Only 55cm of total snow at 2200m with a crust down 23cm. Hard to extrapolate a ton of info out of this site, but what seems to be the common thread among all areas is the buried crust down 22-55cm. So far the bond is doing well with no sign of weakness yet. This will certainly be the layer to watch. In particular the upper extent of it. Where the crust disappears will become critical information in the next while. Wind slabs above this elevation will be touchier and easier to trigger.

As we were leaving the field at 1pm, the winds were just starting to pick up and undoubtedly forming fresh wind slabs in lee (east) areas.

Weather Summary

Winds will fade tonight, and continue slowing down tomorrow. Treeline winds will settle into the moderate range (30km/hr+) tomorrow and be out of the west. As winds drop, temperatures will rise slightly for a daytime high of -8. A few flurries will blow through, but accumulation will be minimal.

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.
Approach lee and cross-loaded slopes with caution.

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.