Archived

Avalanche Forecast

Apr 5th, 2013–Apr 6th, 2013

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

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

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Purcells.

Confidence

Fair - Intensity of incoming weather is uncertain on Saturday

Weather Forecast

Saturday: Overcast with light to locally moderate precipitation possible. Winds moderate from the southwest. Freezing level 1600m. Sunday: A break between off-shore weather systems will bring overcast skies with a trace to light amounts of snow and some possible sunny breaks. Light south winds and 1800m freezing level.Monday: A weak ridge of high pressure starts to influence the weather pattern. Dry conditions and gradually rising freezing levels are forecast.

Avalanche Summary

Numerous natural loose wet avalanches up to size 2.5 during periods of intense solar radiation.

Snowpack Summary

At upper elevations 15-30cm of new snow is covering a crust or moist snow. In some places in the alpine and at treeline this new snow may have buried a recently formed layer of surface hoar or facets. At lower elevations (below 2000m) rain has made the snow surface wet or moist down 50-100cm. New snow combined with wind will has made large cornices even bigger.The March 10th surface hoar/crust interface is buried more than 100cm in most places. Although unlikely to trigger, this deep persistent weakness remains a concern because of the potential for very large avalanches particularly with heavy triggers such as cornice falls or lighter triggers on solar aspects where the crust is more prevalent. Below this the snowpack is strong and well settled.

Avalanche Problems

Wind Slabs

New snow and wind will have created wind slabs in the lee of terrain features.

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.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Loose Wet

With little re-freezing overnight, loose wet avalanches will run on solar aspects if there is rain falling or even short periods of intense solar radiation. Wet slab avalanches are also possible.

Avoid travelling on slopes which are becoming wet due to rain, warm temperatures, or sun.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Cornices

Natural cornice falls are a concern during daytime warming. Cornices may also be triggered easily by traveling near them.

Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 5