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Avalanche Forecast

Archived

Mar 13th, 2024–Mar 13th, 2024

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 possible, human triggered probable.

Regions

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

Spring is poised to make a dramatic entrance in the days to come. As things warm up expect wet loose avalanches and cornices to become a problem. They'll be a problem in themselves, but also as potential triggers for bigger avalanches. Watch sun exposure and temperatures carefully.

Confidence

High

Avalanche Summary

Nothing new today.

Snowpack Summary

5-20cm of recent snow overlies previous wind slabs and sun crust on solar aspects. Expect moist snow on solar aspects if the sun comes out.

The snowpack is quite complex as all of the following layers are all weak:

  1. Buried sun crusts on solar aspects down 20cm will provide a good sliding layer for the new snow to slide if the sun comes out. Be aware of what is above you.

  2. Last weekend's wind slabs are now buried up to 20cm and have possibly been one of the triggers to wake up deeper layers in the snowpack.

  3. The February 2 crust is down approximately 70-100cm and has started to facet out around itself, providing a good sliding layer. This layer was the trigger for most of the avalanches on Sunday.

  4. The basal facets found near the bottom of the snowpack have been triggered by failures of the above layers.

Careful route selection is key as well as taking a closer look at the snowpack to understand where all the weaknesses lie.

GHOST FORECAST AREA

The Ghost area has more snow than usual. With this warming trend, pay close attention of what is above you. Wet loose avalanches and cornice failures are possible in this forecast region. Ice climbers should choose routes appropriately.

Weather Summary

Thursday is looking like a great day. A bit of morning cloud will drift off by mid morning with mostly clear skies behind it. The afternoon will probably see some build up, but nothing too serious. Temperatures will start at -15, but come up to 0 by mid afternoon. Freezing level will be about 2000m. Winds will be light from the W to NW. No snow.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
  • Remote triggering is a concern, watch out for adjacent and overhead slopes.
  • 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.

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.