Archived

Avalanche Forecast

Dec 10th, 2012–Dec 11th, 2012

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

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: Purcells.

Confidence

Fair - Intensity of incoming weather is uncertain on Tuesday

Weather Forecast

Overnight and Tuesday: A warm front is moving across the region tonight and a trailing cold front should move through the region in the morning. The West of the region may get up to 10 mm of precipitation starting early in the morning. Expect very strong westerly winds. The system may dry out quite a bit in the South and East (3-5 mm). Alpine temperatures -8.0 and freezing levels rising to 1000 metres.Wednesday: There is a weak ridge between systems that should bring light precipitation (3-5 mm), light Northerly winds and temperatures down to -12.0 in the alpine.Thursday: The next frontal system is looking weak at this time. Expect light precipitation and SW winds. Check back tomorrow for an update.

Avalanche Summary

No new avalanche activity reported.

Snowpack Summary

There has been a lot of unconsolidated surface snow (about 30-40 cms) that is now available for transport by the forecast strong Westerly winds. Expect wind slabs to develop in the alpine and at treeline. Heavy sluffing may continue to be experienced in sheltered locations. There is still concern about the weak surface hoar layer that is buried down about 100 cms; it may become reactive with the additional load of the new storm.

Avalanche Problems

Storm Slabs

Soft surface slabs are expected to develop into wind slabs due to the forecast strong westerly winds and new snow.

Use ridges or ribs to avoid pockets of wind loaded snow.>Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 4

Persistent Slabs

There are two layers of buried surface hoar in the region. Neither have been reactive since the last storm. Professionals are still concerned about these layers in unsupported terrain.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Avoid open slopes and convex rolls where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 5