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Avalanche Forecast

Archived

Mar 5th, 2024–Mar 6th, 2024

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

Regions

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

The natural cycle is tapering off, but conditions remain primed for human triggering. Discipline is required to manage this condition for some time to come.

Avalanche control is being conducted on the Emerald Lake slide path Mar 6, 2024. Hamilton Lake area, Emerald Peak, and Emerald Basin area are CLOSED.

Confidence

High

Avalanche Summary

Lake Louise patrol reported triggering a size 2.5 persistent slab that ran 250m. Notably, when the shot went off on the cornice above the slope, the cornice pulled back well into flat terrain. They had another explosive result size 2 wind slab.

Sunshine patrol triggered a size 1.5 persistent slab on the Feb 3rd crust. The slab was reloaded onto the previous bed-surface by the wind.

Snowpack Summary

50-90 cm of new snow fell from Feb 23 to March 2 and is now being blown into wind slabs at upper elevations. These slabs overlie the weak Feb 3 facet/crust layer that is down 50-90 cm and exists up to 2500 m and higher on solar aspects. The lower snowpack consists of several facet layers and depth hoar and the base of the snowpack is weak in shallow areas. Goats Eye Profile.

Weather Summary

A high-pressure system is moving into the forecast region tonight bringing clear skies. Temperature will remain seasonally cool with the ridge at -20 and the valley at -10. Moderate SW wind is expected at the ridgeline. No precipitation will occur.

Terrain and Travel Advice

  • Remote triggering is a big concern, be aware of the potential for wide propagations and large, destructive avalanches at all elevations.

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.