Avalanche Forecast

Issued: Feb 28th, 2022 4:00PM

The alpine rating is high, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Storm Slabs and Persistent Slabs.

Avalanche Canada shorton, Avalanche Canada

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New snow, wind, and warming temperature have created dangerous avalanches conditions. Stick to conservative low-angle terrain and avoid travel in the alpine.

Summary

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

MONDAY NIGHT: Cloudy with scattered flurries bringing 5-10 cm of new snow, moderate to strong wind from the southwest, treeline temperatures around -4 C.

TUESDAY: Cloudy with scattered flurries bringing another 5-10 cm of snow, moderate wind from the southwest, treeline temperatures reach -2 C with freezing level climbing to 2000 m around Nelson and 1500 m around Revelstoke.

WEDNESDAY: Mostly cloudy skies, light wind from the south, treeline temperatures around -4 C with freezing level climbing to 1500 m.

THURSDAY: Mostly cloudy with scattered flurries bringing 5-15 cm of snow, light wind from the southwest, treeline temperatures around -6 C.

Avalanche Summary

Reports from the beginning of the storm on Sunday suggest there were widespread natural and human triggered storm slabs across the region. They were mostly small (size 1) in the top 20 cm of new snow, although several size 2 natural avalanches were reported in the Selkirks.

We suspect larger storm slab avalanches occurred on Monday as the storm continued, and these slabs will remain reactive to human triggering on Tuesday.

Over the past week there have been daily reports of large (size 2 and 3) persistent slab avalanches in the Valhalla, Goat, and Kokanee Ranges. While many of the reports have been on north and east slopes, they have occurred on all aspects. The weak layers associated with these avalanches are currently being stressed by the weight of the new snow.

Snowpack Summary

As the storm trails off on Tuesday expect a total of 30 to 50 cm of fresh snow. This snow sits above a variety of layers including heavily wind-affected surfaces on alpine slopes, sun crusts on steep south-facing slopes, and some feathery surface hoar crystal in sheltered areas. With mild temperatures and moderate wind in the forecast, expect to find reactive storm slabs at all elevations, with the most reactive slabs on freshly wind loaded slopes. Two potential weak layers exist within the upper snowpack: the mid-February layer (down 40 to 60 cm) and the late-January layer (down 100 cm). They both consist of surface hoar and/or melt-freeze crusts. Recent trends suggest these layers have been most reactive in southern parts of the region around the Valhallas, Kokanee, and Goat Ranges.

Terrain and Travel

  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • Make conservative terrain choices and avoid overhead hazard.
  • Stick to well supported, lower angle terrain.
  • Travel in alpine terrain is not recommended.

Problems

Storm Slabs

An icon showing Storm Slabs

Storm slab avalanches are likely in steep terrain at all elevations, as 30 to 50 cm of fresh snow needs time to stabilize. Natural avalanches will likely continue on wind loaded slopes in the alpine and human triggered avalanches are likely at all elevations and aspects.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs

Persistent slab avalanches are possible due to two weak layers in the upper snowpack. This includes the mid-February layer (down 40 to 60 cm) and the late-January layer (down 100 cm), both consisting of surface hoar and/or melt-freeze crusts. With increased load from the current storm and warmer temperatures, they have the potential to "wake up" and produce large, unexpected avalanches. The greatest concern is in southern parts of the region where there has been more recent avalanche activity on these layers.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Mar 1st, 2022 4:00PM