Avalanche Forecast

Issued: Mar 4th, 2022 4:00PM

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

Avalanche Canada shorton, Avalanche Canada

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Human triggered avalanches are possible as recent snow slowly strengthens. Danger will be heightened on sun-exposed slopes.

Summary

Confidence

Moderate - Uncertainty is due to the complexity of the snowpack’s structure.

Weather Forecast

FRIDAY NIGHT: Clear skies, light wind from the north, treeline temperatures drop to -10 C.

SATURDAY: Mix of sun and cloud, light wind from the northwest, treeline temperatures reach -5 C.

SUNDAY: Sunny, light wind from the west, treeline temperatures reach -5 C.

MONDAY: Cloudy with isolated flurries bringing up to 5 cm of snow, moderate wind from the northwest, treeline temperatures reach -5 C.

Avalanche Summary

We have seen a gradual decline in the reactivity of storm slabs since the natural avalanche cycle on Monday and Tuesday. There were still numerous size 1-1.5 human triggered slabs on Thursday, involving 20 to 50 cm of recent storm snow above recently buried surface hoar and crust layers. These have occurred on all aspects and elevations, although below treeline elevations have seen more wet loose avalanches than slab avalanches recently. Storm slab avalanches have been more frequent and larger in the Selkirks than in the Monashees.

Over the past two weeks we have seen sporadic large (size 2 to 3) persistent slab avalanches on buried surface hoar and crust layers. Most of the activity has been in the Valhalla, Goat, and Kokanee Ranges. Recent weather trends have helped stabilize these layers, but we aren't quite ready to rule out the possibility of large persistent slab avalanches in parts of the region. Most recently, we received one report of a size 2 human-triggered persistent slab avalanche on Wednesday at 2200 m in the Valhallas.

The main concerns this weekend are lingering storm slabs, and the potential impact of sunny weather weakening sun-exposed snow and cornices.

Snowpack Summary

Recent storm snow has likely settled into 30 to 50 cm of heavy powder at upper elevations, but is becoming moist and crusty on south-facing slopes and all aspects below 1800 m. Recent storms have delivered more snow to the Selkirks than the Monashees.

The snowpack is generally well settled below the new snow, although there are two potential weak layers buried 50 to 100 cm deep. They both consist of surface hoar and/or melt-freeze crusts. Recent trends suggest these layers have been more reactive in southern Selkirks around the Valhalla, Kokanee, and Goat Ranges. We are uncertain about the reactivity of these layers after recent temperature fluctuations.

Terrain and Travel

  • If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
  • Investigate the bond of the recent snow before committing to your line.
  • Avoid exposure to steep sun exposed slopes.
  • Be carefull around freshly wind loaded features.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.

Problems

Storm Slabs

An icon showing Storm Slabs

 30 to 50 cm of recent storm snow is bonding relatively quickly in most areas, but may still produce avalanches in specific terrain features. This includes steep sun-exposed slopes, wind loaded slopes, and open convexities at treeline where there could be buried sun crusts or surface hoar layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs

Persistent weak layers have gained strength over the past week, but it may still be possible to trigger large avalanches on buried surface hoar or crust layers found 50 to 100 cm deep. The problem is most likely found in the southern part of the Selkirks (e.g. Valhalla, Goat and Kokanee ranges), especially on open convex slopes.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Mar 5th, 2022 4:00PM