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Avalanche Forecast

Archived

Jan 31st, 2023–Feb 1st, 2023

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, human triggered possible.

Regions

Kootenay Boundary, Bonnington, Kootenay Pass, Norns, Rossland, South Okanagan, Ymir, Moyie, St. Mary.

Wind slabs continue to be triggered by riders in this region. Watch for wind-affected snow as you transition into open terrain features on all aspects at treeline and alpine elevations.

Confidence

Moderate

Avalanche Summary

On Monday, skier-triggered wind slabs, up to size 1 were reported from steep terrain features.

On Sunday, a few natural loose dry avalanches were reported up to size 1.5 in steep terrain.

On Saturday, explosives control produced wind slab avalanches to size 2 on southern aspects. Several size 1 wind slab avalanches, triggered by skier traffic, were reported throughout the region. A few size 1 natural loose dry avalanches were observed in steep terrain.

Thank's for all the MIN's! Please continue to share any observations or photos on the Mountain Information Network.

Snowpack Summary

Recent snow continues to be redistributed by variable winds at alpine and treeline elevations. On steep southerly aspects, snow sits above a melt-freeze crust while on northerly aspects it overlies previously wind-affected surfaces.

Several weak layers are found mid-snowpack. A surface hoar layer from early January is found down 40-80 cm. Observations suggest that this layer is slowly rounding. If preserved it would be found in sheltered and shaded terrain features.

A thick melt-freeze crust from Boxing Day is buried 70-100 cm deep. This layer is helping to cap lower snowpack weaknesses but at higher elevations, this crust is thinner and less supportive.

The lower snowpack contains weak and faceted grains. Professionals continue to monitor weak layers in the snowpack however they are not active avalanche problems at this time. Avoid shallow, rocky areas where snowpack transitions from thick to thin and triggering weak layers is more likely.

Weather Summary

Tuesday Night

Mostly cloudy and isolated flurries, trace accumulation. Southwest ridgetop winds 10 - 15 km/h. Treeline temperatures -10°C.

Wednesday

Mainly cloudy, with 5 to 10 cm accumulation. 10 to 20 km/h ridgetop winds. Treeline temperatures high -6°C

Thursday

Partial clouds, no new snow, increasing southerly winds 15 to 30 km/h, treeline temperatures high -5°C

Friday

Mostly cloudy, 10 cm new snow, 10 km/h southerly winds, treeline temperatures high -3°C

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Approach lee and cross-loaded slopes with caution.
  • Wind slabs may be poorly bonded to the underlying crust.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.

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.