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Avalanche Forecast

Archived

Mar 20th, 2024–Mar 21st, 2024

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

Regions

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

A return to winter with 10-20 cm of snow in the forecast will refresh the ski quality!

Watch for sluffing in steep terrain at all elevations.

Confidence

Moderate

Avalanche Summary

No new avalanches were observed or reported on Wednesday

Snowpack Summary

10-20 cm of new snow with moderate SW winds is creating windslabs in alpine lee terrain. This sits on widespread melt freeze crusts which exist everywhere except high north aspects (above 2100m). Below this, the Feb 3rd crust layer exists down ~ 50 -100 cm. Basal facets persist in thin snowpack areas and total snowpack depths range from 90-170 cm at treeline.

Weather Summary

A cold front is upon us and most areas should see 10-25 cm of new snow by Thursday AM. Winds will be light to moderate and temperatures will be in the -5 to -10 range.

The system gradually leaves the area on Friday and Saturday but expect to see some residual upslope precipitation (more snow on the east side of the range). Temperatures will cool to -5 to -15 and winds will be generally light.

Click here for more weather info.

Terrain and Travel Advice

  • Closely monitor how the new snow is bonding to the crust.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.

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.

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.