Avalanche Forecast

Issued: Dec 7th, 2014 8:18AM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Storm Slabs and Persistent Slabs.

rbuhler, Avalanche Canada

South Columbia.

Watch for signs of changing stability as the temperature rises during the day.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

A warm, wet storm system will reach the coast early Monday. The interior should remain mostly dry for Monday but light flurries are possible in the afternoon. Temperatures will rise rapidly on Monday with the freezing level reaching around 1500m and winds increasing to moderate in the alpine. On Tuesday, the S. Columbia region will begin to see precipitation (5-10mm) and the freezing level are expected to rise to 2000m or higher. Wednesday is expected to be similar with freezing levels around 2000m and precipitation. Amounts are uncertain for Tuesday night and Wednesday with models currently showing 10-30mm. Strong alpine winds from the SW are expected for both Tuesday and Wednesday.

Avalanche Summary

There have been reports of isolated size 1 storm slab avalanches trigger by ski cuts. These are on NW-NE slopes in the alpine and I expect wind loading contributed. Also reports of loose sluffing from steep terrain features.

Snowpack Summary

15-20cm of new snow sits on a weak layer of surface hoar and/or a sun crust. In windier places, this new snow may have formed wind slabs in leeward features. Below around 1800m elevation and down around 20-30cm is a rain crust but it appears that the snow above it is generally well bonded. About 1m down, a weak layer of surface hoar and/or facets can be found in some locations. Snowpack tests on this layer are showing improving results, but in some locations "pops and drops" indicate this beast could still be touchy. A thick rain crust with facets from early November is buried over 1 m down. We may see these deep weak layers become a problem again with the upcoming storm system.

Problems

Storm Slabs

We are at the early stages of a storm slab problem. Wind loaded features are the main concern at the moment. As we add warming and new precipitation to the equation, this problem is expected to become more widespread.

Be cautious as you transition into wind affected terrain.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

The chances of triggering a persistent slab have decreased, but the consequences are still high. Any slopes that did not avalanche during the last storm cycle should still be considered potentially hazardous.

Choose well supported terrain without convexities.>Avoid common trigger zones including thin snowpack areas, near rocky outcrops, and steep alpine slopes.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Dec 8th, 2014 2:00PM