Avalanche Forecast

Archived

Feb 25th, 2023–Feb 26th, 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 possible, human triggered probable.

Below Treeline

Natural avalanches unlikely.

Regions

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

Natural avalanche activity is tapering, but still happening. Avoid wind loaded terrain in the alpine!

Confidence

Moderate

Avalanche Summary

Natural activity continued today. Active avalanches were reported near Tent ridge. Sz 2-2.5 and running full path.

Snowpack Summary

Today we went to dig a profile at one of our standard locations, the Dog Leg area. We found 152 cm of snow in a moderately wind loaded treeline area. The 20-30cm of new snow is sitting on a 2cm thick, dense (pencil) wind crust layer. We wondered if this is what the recent cycle was sliding on, but that's just speculation. We had a failure on that layer in tests. Below the wind crust, we encountered the dreaded facets at about 50cm down. The Nov interface is down 110cm. Here, the snowpack is mostly depth hoar and large facets. On a more general note the winds were transporting tons of snow today. Any exposed area from E to S is heavily loaded. Cornices are also growing with the wind.

Weather Summary

Wind. Sailors might like a forecast like ours, but for us skiers/climbers/winter enthusiasts, the wind gets old in a hurry! Winds will increase yet again tonight with high alpine wind hitting the 70km/hr range, but fading to a mere 50km/hr by noon. In lower terrain, expect more like 30-40km/hr and gusty. Skies will be mixed, with maybe a few flurries. Does snow whipped up by the wind count as a flurry? Temperatures? These will be between -12 and -8.

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.
Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

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.