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Avalanche Forecast

Archived

Feb 13th, 2024–Feb 14th, 2024

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

Regions

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

Keep isolated wind slabs in mind in the alpine, and also remember that triggering a persistent slab is not outside the realm of possibility. Steep thin snowpack areas seem particularly suspect.

Confidence

Moderate

Avalanche Summary

A size 2 and 2.5 skier-triggered deep persistent slab in the Cirque Forepeak area occurred Tuesday showing that the persistent layers can still be triggered in thin snowpack areas.

Lake Louise patrol reported triggering very small and thin wind slabs in high alpine lee areas with ski cuts.

Sunshine Patrol reported triggering soft slabs 5-10cm thick with ski cuts in the alpine.

No avalanches were observed by the field on Mt. Whymper today.

Snowpack Summary

10-25 cm of recent storm snow sits over the Feb 3 crust. Isolated wind slabs are present in alpine lee areas. The Feb 3 crust is present on all aspects except north above 2500 m and ranges from 1-15 cm thick, with the thickest found in Yoho. Mid-pack persistent 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

The wind will diminish to the light range for the next two days, and calm-ish conditions are expected. A high-pressure system will build into the region on Wednesday. Lingering cloud will be present until Thursday. No precipitation is expected for a few days. Temperatures will be seasonal with -5 in the valley and -20 at the ridge line.

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.