Avalanche Forecast

Issued: Jan 17th, 2014 8:41AM

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

jlammers, Avalanche Canada

Cariboos.

Warm temperatures and sunny skies forecast for the next few days will have a significant weakening effect on the snowpack. If solar radiation is particularly strong the avalanche danger could rise to HIGH.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Saturday

Weather Forecast

A ridge of high pressure will continue to dominate the region bringing dry conditions and mainly clear skies for the foreseeable future. Winds should be light to moderate from the west on Saturday, becoming northwesterly on Sunday and Monday. An inversion is expected for Saturday bringing valley cloud and alpine temperatures reaching +5.0. General cooling is expected for Sunday and Monday.

Avalanche Summary

No new avalanches were reported on Thursday; however, with current warming there is a high likelihood of loose wet avalanche activity with serious potential to re-activate deep persistent weaknesses.

Snowpack Summary

Snowpack depths vary, but in general there is now 200 to 250cm of snow at tree line and as much as 300 cm in select places in the alpine. In some areas we're still dealing with a relatively thin snowpack thanks to a windy early season and strong winds scouring slopes during recent storms. Roughly 100cm of snow fell last week and has been blown into stiff wind slabs in many areas. Below the recently formed storm slab you may find soft facetted snow and/or surface hoar buried around January 8th. This layer may coexist with a crust at lower elevations. Surface hoar layers buried in November and early December may still be found in the mid to lower snowpack, but are generally considered to be unlikely to trigger.A basal facet/crust combo (weak sugary snow above and below a crust) near the ground is still a concern in some areas and was likely the culprit with some of the very large avalanches reported in the wake of last week's storm..

Problems

Deep Persistent Slabs

Continued warming will increase the likelihood of triggering a number of persistent weaknesses in the snowpack. Possible triggers include cornice fall. A deep persistent slab avalanche would be highly destructive in nature.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Be aware of the potential for full depth avalanches due to deeply buried weak layers.>Avoid convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Loose Wet

Continued warming will likely produce loose wet avalanches in steep, sun-exposed terrain. A loose wet avalanche in motion may also "step down" triggering deep and destructive slab avalanches.

Sluffs may trigger deeper instabilities.>Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. >Avoid exposure to solar aspects overhead, large avalanches may reach the end of run out zones.>

Aspects: North, North East, East.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Wind Slabs

Although recently formed windslabs have gained considerable strength, they may still be triggered in steep, unsupported terrain. Watch for increased triggering with forecast warming.

Be aware of the potential for wide propagations due to the presence of hard windslabs.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1 - 4

Valid until: Jan 18th, 2014 2:00PM