Archived

Avalanche Forecast

Mar 8th, 2017–Mar 9th, 2017

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

2: Moderate

The avalanche danger rating below treeline will be moderate

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

2: Moderate

The avalanche danger rating below treeline will be moderate

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

3: Considerable

The avalanche danger rating below treeline will be considerable

Regions: South Rockies.

The best and safest riding will likely be found in sheltered, lower elevation terrain.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Thursday: 2-4cm of new snow / Light southwest winds / Alpine temperature of -10Thursday night and Friday: up to 15cm of new snow / Strong to extreme southwest winds / Alpine temperature of -7Saturday: Mix of sun and cloud / Moderate southwest winds / Alpine temperature of -3 / Freezing level at 1500m

Avalanche Summary

On Monday, explosive control and ski cutting produced size 1-1.5 avalanches at treeline and in the alpine. A cornice fall in Waterton Park resulted in a Size 2.5, entraining lots of snow. Natural activity is expected to taper off, but storm and wind slabs will remain susceptible to human triggering.

Snowpack Summary

We've had daily snowfalls of 5-15cm since Saturday, bringing the total from the past week to 50-80 cm. At times, strong southwesterly winds redistributed the new snow onto leeward slopes, building thicker and stiffer slabs. The new snow will likely have a poor bond to the old snow interface that consists of stiff wind slabs, crusts, and facets.The mid-pack in this region is generally strong, but the bottom third of the snowpack is composed of weak facets (sugary snow crystals). Approximately 100-120 cm of settled snow sits above this weak layer of sugary, rotten facets that developed in December. This remains a concern and should be on your radar, especially with the recent loading from snow and wind.

Avalanche Problems

Wind Slabs

Gusty southwest winds at upper elevations have formed fresh wind slabs on leeward slopes and behind terrain features. Watch for conditions that change with elevation.

Use caution in lee areas. Recent wind loading has created wind slabs.Be cautious as you transition into wind affected terrain.Stay off recent wind loaded areas until the slope has had a chance to stabilize.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Deep Persistent Slabs

A weak layer near the base of the snowpack has the potential for large avalanches, especially in areas with minimal rider compaction or thin variable snow cover.

Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.Be aware of the potential for full depth avalanches due to weak layers at the base of the snowpack.Avoid steep convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 4