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Avalanche Forecast

Archived

Feb 1st, 2022–Feb 2nd, 2022

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

Regions

Little Yoho.

Touchy storm slabs that sit on a well preserved surface hoar layer are the biggest concern right now.

Weather Forecast

Cold air will continue through Wednesday and then start to warm up on Thursday. Valley bottom temps on Wednesday in Lake Louise will be -15. Flurries forecast for Thursday, but little accumulation. Ridgetop winds will pick up Wed afternoon into the mod to strong range.

Snowpack Summary

15-35 cm storm snow has created fresh windslabs in the alpine. Storm slabs exist at tree-line and below treeline elevations where storm snow sits on a touchy surface hoar layer. This was very apparent on Mt Field on Monday but this problem is expected to exist in other areas within the forecast region. Expect easy triggering of these soft slabs.

Avalanche Summary

Field team to Mt Field on Monday experienced numerous ski-cut and natural avalanches on the storm snow interface down 25-35 cm. The storm snow was sitting on a 3-5 mm well preserved surface hoar layer. Ski hills reported several small natural and explosive triggered windslabs in the alpine.

Confidence

Wind speed and direction is uncertain on Thursday

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.

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.