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Archived

Avalanche Forecast

Mar 22nd, 2015–Mar 23rd, 2015
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
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
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: South Coast.

Touchy conditions exist in the North of the region with the potential for large and destructive avalanches.

Confidence

Fair - Due to the number of field observations on Sunday

Weather Forecast

Scattered convective snowfall (up to 10cm) is expected on Monday as a cold front moves across the region. By late Tuesday a short-lived ridge will bring clearing. On Wednesday a more organized warm and wet frontal system will bring rain to most elevations. Ridgetop winds are expected to be moderate from the southwest with Monday's snowfall, otherwise remaining light. Freezing levels should hover around 1500m on Monday and Tuesday, and then climb to about 2500m with Wednesday's system.

Avalanche Summary

Over the past week, there have been a number of avalanches to size 2.5 occurring on the March 11 persistent weak layer. Some avalanches have occurred naturally, or remotely from distances of up to 100m. Hot spots for avalanche activity seem to include the Duffey Lake area, the Birkenhead drainage, the Hurley and the South Chilcotins. Snow and wind on Monday will likely add a round of wind slab activity to the mix. But it will also add load to the March layer, potentially adding to its reactivity and destructive potential.

Snowpack Summary

New wind slabs have formed in response to recent wind, snowfall and warm temperatures. At lower elevations, rain has saturated the snowpack. Cornices may also be fragile. A touchy crust/facet persistent weak layer, buried up to 60 cm down, has been reactive producing easy test results at upper treeline and alpine elevations, especially in the north of the region (see avalanche summary). Avalanche problems associated with this layer may linger for a while with the potential for surprisingly large and destructive avalanches. Below this, the snowpack is reported to be generally well-settled and strong.

Avalanche Problems

Persistent Slabs

Easy snowpack test results and large natural avalanches indicate that a recently buried crust/facet layer deserves our respect. Touchy conditions are expected to persist for the foreseeable future, especially in the north of the region.
Choose conservative lines and watch for clues of instability.>Pay attention to overhead hazards.>Avoid steep convexities or areas with a thin or variable snowpack.>Remote triggering is a concern, watch out for adjacent slopes.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 4

Wind Slabs

Wind and snow forecast for Monday may form touchy new wind slabs in high elevation lee terrain. Watch for triggering in the lee of ridge crest and terrain breaks.
Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3