Avalanche Forecast

Issued: Mar 18th, 2016 9:37AM

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.

Rising freezing levels over the weekend will increase the likelihood of large natural and human triggered avalanches. Avoid slopes with overhead exposure where falling cornices could trigger large avalanches

Summary

Confidence

High

Weather Forecast

Another sunny day forecasted for Saturday but the big change is freezing levels rising to around 1900m.Â Cloudy skies are expected to return either Saturday evening or Sunday morning, but the exact timing of this is uncertain.Â If it's cloudy Saturday night, the hazard will increase on Sunday due to lack of "crust recovery". Freezing levels rise again on Sunday to around 2000m.Â Flurries are expected for Monday.Â Light to moderate southerly ridgetop winds are forecasted throughout the period.

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. On Thursday, two natural size 3 slab avalanches were reported in the alpine.Â One on a north aspect and the other on a south aspect. Additionally, several small cornice failures triggered size 2 slab avalanches. 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. Moderate westerly winds have created fresh wind slabs on top of old wind slabs on lee features at treeline and in the alpine. 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.

Problems

Cornices

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

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

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.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Choose well supported terrain without convexities.>Use conservative route selection, stick to moderate angled terrain with low consequence.>

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.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Sluffs may trigger deeper instabilities.>Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. >

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

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Valid until: Mar 19th, 2016 2:00PM