Avalanche Forecast

Issued: Mar 17th, 2016 8:54AM

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

jsmith, Avalanche Canada

Cariboos.

Solar radiation and increasing freezing levels will increase natural avalanche activity. Avoid slopes with overhead exposure where falling cornices could trigger large avalanches.

Summary

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

The ridge over the province begins to break down on Friday with increasing clouds on Saturday and perhaps some flurries on Sunday. Expect winds to be generally light and southerly. The BIG news is the increasing freezing levels on Saturday(~2000m) which may be followed by poor crust recovery Saturday night and even higher freezing levels on Sunday(~2200m).

Avalanche Summary

On Monday, 2 sledders were killed in an avalanche near Blue River. We still have very little information about the incident. More details will be made public as they become available. In recent days, a smaller surface avalanche stepped down and triggered a size 3 slab on a southwest facing slope at treeline. The late February surface hoar layer was the likely weak layer associated with this avalanche. This illustrates the potentially touchy and destructive nature of the late February interface. Solar radiation and increasing freezing levels will become the driver for natural avalanche activity in the coming days.

Snowpack Summary

At ridgetop, cornices are huge and could become increasingly touchy with forecast solar radiation. Convective flurries on Wednesday produced highly variable amounts of low density snow ranging from 15-30cm. Moderate westerly winds have created fresh wind slabs on lee features at treeline and in the alpine. The new snow overlies buried wind slabs. 70-100cm 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.

Problems

Cornices

Daytime warming and solar radiation will promote large cornice failures which could, in turn, trigger a large avalanche on the slope below.

Extra caution needed around cornices with current conditions.>Avoid areas with overhead hazard.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 5

Persistent Slabs

The late February layer is becoming less likely to trigger, but it continues to surprise riders with large avalanches. I'd aim for well-supported slopes without convexities, and I'd be increasingly cautious as solar radiation comes into play.

Use conservative route selection, stick to moderate angled terrain with low consequence.>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

Loose Wet

As the sun comes out, surface avalanche conditions will include a mix of wind slabs in high elevation lee terrain, and pushy loose wet activity on steep, sun-exposed slopes. Loose wet avalanches may also trigger deep and destructive slab avalanches.

Sluffs may trigger deeper instabilities.>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: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Valid until: Mar 18th, 2016 2:00PM