Avalanche Forecast

Issued: Mar 14th, 2016 9:21AM

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

jlammers, Avalanche Canada

Cariboos.

As stormy weather tapers-off and a dry ridge gradually builds over the province, solar radiation may become the driver for natural avalanche activity.

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

Light snowfall (2-3cm) is expected on Tuesday and early Wednesday. Clouds are expected to scatter throughout the day on Wednesday, while clear skies are forecast for Thursday. Ridgetop winds are expected to be generally light to moderate and southwesterly on Tuesday, switching to northwesterly by Wednesday. Daytime freezing levels should hover around 1200m for the forecast period.

Avalanche Summary

On Sunday, natural and human triggered wind slab activity to size 1.5 was observed on a variety of aspects at treeline and in the alpine. The avalanches formed in response to new snow and wind on Saturday. In one case, a smaller surface avalanche stepped down and triggered a size 3 slab on a southwest facing slope at treeline. It is unknown what interface the larger slab failed on. As stormy weather tapers-off and a dry ridge gradually builds over the province, solar radiation may become the driver for natural avalanche activity.

Snowpack Summary

At treeline and in the alpine you're likely to find wind slabs which formed during Saturday's stormy weather. 50-100cm below the surface you'll find a persistent weak layer comprised of surface hoar, facets and/or a thick crust. This layer seems variably reactive. In other words, it's still really touchy in some places while in other spots it's really tough to trigger, and there's not much of a reliable pattern telling us what exact aspects are most suspect. I'd continue to be suspicious of steep, unsupported features at treeline and in the alpine as this layer has the potential for very large avalanches. Below this interface, the snowpack is generally gaining strength. At ridgetop, cornices are huge and potentially unstable.

Problems

Persistent Slabs

A persistent weakness lies buried up to 100cm below the surface. Although this layer is slowly becoming less likely to trigger, it has the potential to surprise with nasty consequences. I'd continue riding with a conservative mind set.

Choose well supported terrain without convexities.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 5

Wind Slabs

Recently formed wind slabs may remain sensitive to light inputs in higher elevation lee terrain. Brief periods of solar radiation may also promote loose wet avalanche activity on steep, sun-exposed slopes.

Be cautious as you transition into wind affected terrain.>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

Expected Size

1 - 3

Cornices

Large cornices loom over open bowls and alpine faces. Not only are massive cornice falls a hazard in themselves, they can also act as a heavy trigger for slab avalanches on the slope below, especially during periods of solar warming.

Extra caution needed around cornices with current conditions.>Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Valid until: Mar 15th, 2016 2:00PM