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Archived

Avalanche Forecast

Mar 24th, 2022–Mar 25th, 2022
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Kootenay Boundary.

Be thoughtful with your terrain choices, and pay attention to how the weather is affecting the snowpack through the day. Uncertainty about a buried persistent weak layer would make me hesitant to ride a big, committing feature.

Confidence

Moderate - The snowpack structure is generally well understood. Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Weather Forecast

THURSDAY NIGHT: Partly cloudy. No new precipitation expected. Light southeast ridgetop wind. Freezing level around 1750 m. 

FRIDAY: Partly cloudy. No new snow expected. Light southwest ridgetop winds. Freezing level rising to around 2100 m.

SATURDAY: Partly cloudy. No new snow expected. Light south ridgetop wind. Freezing level around 2200 m. 

SUNDAY: Mostly cloudy. Light rain overnight, possible snow at high elevations. Light to moderate southwest ridgetop wind. Freezing level rising to 2500 m. 

Avalanche Summary

On Tuesday and Wednesday, widespread, loose wet avalanches were reported due to warm temperatures and/or sunshine (size 1-2). 

There have been some notable human-triggered avalanches in Kootenay Pass and the Nelson area in the past week. These large slab avalanches (size 2), failed on either a buried sun crust on solar aspects or surface hoar on shaded aspects. On Wednesday, south of Nelson, a large, naturally triggered avalanche was reported that may have failed on or stepped down to this layer. It started on an east through southeast aspect just above treeline.

Snowpack Summary

A skiff of new snow and possibly thin windslabs in the high alpine. Refrozen crust on all aspects up to 2200 m, softening in the afternoon at low elevations and on steep, sunny slopes. Recent warm temperatures, sun, and rain have made the top 10-30 cm of the snowpack moist. Below 1500 m, the snowpack may be wet and isothermal if the freezing levels don't drop enough overnight. 

40 to 70 cm below the snow surface, you'll find a frozen sun crust on solar aspects, and weak, feathery surface hoar crystals on shaded aspects. This layer was buried in early March. During the last storm, it produced surprising avalanches in certain areas of the Selkirks (east side of the region). The recent warm weather seems to have helped this layer heal, but it's not yet time to take it out of your danger assessment for the day.

The mid and lower snowpack are generally strong and well bonded.

Terrain and Travel

  • If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
  • Be aware of the potential for large avalanches due to the presence of a persistent slab.
  • Be alert to conditions that change with aspect and elevation.
  • When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.

Avalanche Problems

Persistent Slabs

This layer is getting harder for riders to trigger, but it is possible that it could still produce large, surprising avalanches.

This layer is a concern where there is a poor bond to underlying surface hoar crystals on north-facing slopes. This problem seems most pronounced in the Selkirks around Nelson and around Kootenay Pass.

Aspects: North, North East, East, West, North West.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 1.5 - 3

Loose Wet

Temperatures are forecasted to stay quite steady overnight, and the surface snow may not solidly refreeze at lower elevations. Paying close attention to how thick and supportive the surface crust is throughout the day will help you avoid any lingering wet loose avalanche problems below treeline. 

Aspects: All aspects.

Elevations: Below Treeline.

Likelihood: Possible

Expected Size: 1 - 2