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Avalanche Forecast

Archived

Mar 28th, 2024–Mar 29th, 2024

Alpine
Natural avalanches unlikely.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.

Regions

Banff Yoho Kootenay, Little Yoho, Lake Louise, West Side 93N, Field.

Triggering the Feb 3 persistent weak layer remains the greatest concern. We have not seen any activity on this in the deeper snowpack areas.

Use caution in areas with a snowpack depth lower than 200cm on shaded slopes above 2000m where events to the east have occurred.

Expect to find developing new slabs with the incoming snow and winds

Confidence

Moderate

Avalanche Summary

No new avalanches were observed in this sub-region in the last week, however in thinner snowpack areas east of the divide:

There has been four size 2-3 avalanches that have all been remotely or accidentally triggered by skiers. All occurred on northerly aspects between 2000 - 2600m in thin snowpack areas (less than 200cm) with no overlying March 20 crust.

These have all initiated on the Feb. 3rd crust/ facet interface and stepped down to basal facets / ground.

Snowpack Summary

Up to 15cm of storm snow covers sun crusts on solar aspects and up to 30 cm of dry snow on shaded slopes. Below this, the March 20th crust exists everywhere except north aspects above 1800.

Our main concern is thin snowpack areas (read: 200cm or less) on northerly aspects where there is no March 20 crust. Here the mid-pack Feb 3 facet / crust layer and the basal facets / depth hoar remain sensitive to triggering.

Deeper snowpack areas have fewer concerns.

Weather Summary

Thursday evening: light snowfall will linger with freezing levels to valley bottom. Light to moderate SW winds at ridgetop.

The same light snowfall will continue Friday with freezing levels near 1500m and winds shifting NW.

Scattered flurries Saturday.

Skies clear and freezing levels rise to 2000m Sunday as winds increase: moderate to strong.

Click here for more weather info.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
  • Remote triggering is a concern, watch out for adjacent and overhead slopes.

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.