Avalanche Forecast

Archived

Jan 29th, 2023–Jan 30th, 2023

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

Despite the very cold temps Sunday morning, parties got out and enjoyed perfect blue bird sky's and reasonable skiing. Reverse loading (Winds from the NW) will build new reactive windslabs in A-typical features, use caution when entering S-SE terrain in open treeline and alpine terrain.

Confidence

Moderate

Avalanche Summary

A road patrol down the spray today with perfect visibility noted no new avalanches. However lots of snow transport from the Moderate to Strong N winds all day promoting possible reverse loading.

Snowpack Summary

On average 10cm of new snow fell at treeline with some areas seeing more and some a bit less. Valley bottoms (where snow is needed the most) was where it was less with only around 5cm accumulation. This new snow is overlying a thin melt freeze crust up to 2100m that makes the skiing very challenging but so far the bond appears to be good. The upper snowpack continues to strengthen with the only notable sheer at the interface with the deeper weak facets in the moderate range. Isolated windslabs were observed in alpine areas on southern aspects from the recent northerly winds but they do not extend far downslope.

As the snowpack above the weaker base becomes more cohesive the potential for wide propagation increases. This will be a common theme this winter and you should always be thinking about consequences of an avalanche.

Turns are pretty hard to come by as one forecaster described the area as the worst they have ever seen.....

Weather Summary

Sunday proved to be a cold morning with -36 at Mud lake. But the day warmed up to -15 and the sun is starting to pack a punch. Monday will see slightly cloudy sky's day time highs of -17 and a Moderate West wind. No snow to speak of...

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

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.