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Avalanche Forecast

Archived

Feb 11th, 2024–Feb 12th, 2024

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

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

The avalanche hazard has increased slightly with new wind slabs and sluffing in steep alpine terrain features. Some weaknesses persist in the mid and lower snowpack, and while reactivity of the lower layers has been limited, avalanches are still possible. Keep this in mind if entering steep committing terrain.

Confidence

High

Avalanche Summary

There are numerous reports of new wind slabs over the Feb. 3 crust causing avalanches (size 1 to 1.5) at treeline and above. Also, there were a couple of deeper and larger releases, mainly on the mid-pack facets, but also a deeper one to ground in steep terrain on Fairview in the last 24 hours.

Snowpack Summary

Wind slabs have formed in lee areas of the alpine with increased west winds and some sluffing in steep terrain. 10-25 cm of recent storm snow sits over the Feb 3 crust that is present on all aspects except north above 2500 m. This crust ranges from 1-15 cm thick, with the thickest found in Yoho. Mid-pack weak layers from Jan and Dec are down roughly 30 and 50 cm respectively. Facets and depth hoar make up the basal layers of the snowpack in most locations.

Weather Summary

Monday: Cloudy with trace amounts of snow East of the divide and 2cm West of the divide, alpine winds 25-35kmh switching from West to NW and valley bottom freezing levels

Tuesday: Partly cloudy, no snow, light N/NW winds, and valley bottom freezing levels.

For more mountain weather, click HERE.

Terrain and Travel Advice

  • Wind slabs may be poorly bonded to the underlying crust.
  • Watch your sluff: it may run faster and further than you expect.
  • Avalanche hazard may have improved, but be mindful that deep instabilities are still present.

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.