Archived

Avalanche Forecast

Jan 18th, 2014–Jan 19th, 2014

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

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

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: South Rockies.

Daytime heating and solar radiation will play a large role in the danger rating for the next few days.

Confidence

Good - Timing or intensity of solar radiation is uncertain

Weather Forecast

Overnight: Temperatures cooling down, nil precip., freezing level at valley bottom, light to moderate SW winds.Sunday: Sunny with some cloudy periods, nil precip., variable light winds. Freezing level around 900m.Monday: Sunny with some cloudy periods, nil precip., light winds, freezing level at valley bottom.Tuesday: Sunny with some cloudy periods, nil precip., light winds, freezing levels rise to around 1300m.

Avalanche Summary

1 size 2.5 snowmobile triggered avalanche in steep shallow snowpack, failing to near ground level. Areas of shallow snowpack are of special concern, as well as areas where there is a hazard from above such as cornices or steep south facing cliffs.

Snowpack Summary

Extensive wind transport and wind slab development has occurred in all areas of the region. Recent storm snow varies from 40-70 cm across the region and in some alpine areas storm slabs are more than a metre thick. Persistent weak layers of buried crusts/facets/surface hoar continue to be a concern, and may have been the failure plane for recent large natural avalanches. Forecast very warm temperatures may result in loose wet avalanches or cornice falls that may trigger the persistent weak layer at the base of the snow pack ( depth hoar ). Strong solar radiation combined with above freezing temperatures in the alpine could create very touchy triggering on Southerly aspects.

Avalanche Problems

Wind Slabs

Strong winds have created hard wind slabs in the alpine and at tree line, very warm temperatures and strong solar radiation may increase the likelihood of triggering. A cornice failure or radiation sloughing in cliffs may trigger lower slopes.

Watch for areas of hard wind slab in steep alpine features.>Avoid exposure to sun exposed slopes.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 4

Persistent Slabs

Recent storm snow and hard wind slabs have been added to the load above buried weak layers. Deeply buried weak layers may become harder to trigger, but the consequences are very large destructive avalanches.

Be aware of the potential for large, deep avalanches due to the presence of buried facet/crust layer and depth hoar layer.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 3 - 6

Cornices

Cornices may become weak and fall off naturally due to strong solar radiation and forecast warm alpine temperatures. Cornice falls are a large load that may release buried persistent weak layers on slopes below, resulting in very large avalanches.

Cornices become weak with daytime heating. >Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3