Avalanche Forecast

Issued: Jan 28th, 2016 8:56AM

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

jlammers, Avalanche Canada

South Coast.

In the north of the region, persist weak layers are more likely to have endured recent storms. In these areas, the alpine Avalanche Danger may be High on Friday.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

On Friday expect 5-15cm on new snow, strong southwest winds and freezing levels at about 1000m. On Saturday and Sunday, the region will see another 5cm of new snow each day with freezing levels hovering around 800m. Winds for Saturday will be mainly moderate and southwesterly, switching to light and northerly on Sunday.

Avalanche Summary

In recent days, backcountry avalanche observations have been extremely limited, mostly due to stormy weather. That said, I'm sure there was a widespread natural avalanche cycle on Thursday in response to heavy storm loading. Forecast cooling should help gradually reduce natural avalanche activity. But, for the short term storm slabs will likely remain sensitive to light loads, while potential remains for very large persistent slab avalanche activity.

Snowpack Summary

On Wednesday night and Thursday morning, heavy snowfall and strong winds continued to form deep and dense storm slabs in high elevation terrain and cause substantial cornice growth. At treeline and below, rain fell and further saturated the snowpack. The snow line fluctuated a great deal during the storm which dropped up to 60mm of precipitation throughout the region.Where it still exists, the mid-January surface hoar layer is between 70 and 150 cm below the surface. The hope is the combination of heavy storm loading and warm temperatures has flushed out this weak layer in most areas, but that remains to be seen. In the wake of the storm, there will be a lot of uncertainty regarding the reactivity and distribution of this destructive persistent avalanche problem, especially at high elevations in the north of the region where continued reactivity at this interface has been observed. Additionally, the snowpack will require time to adjust to the stress of heavy storm loading. A very conservative approach to mountain travel is still required.

Problems

Storm Slabs

Continued snowfall and strong winds on Friday will contribute to an ongoing storm slab problem. Watch for increased triggering in wind-exposed terrain.

Be cautious as you transition into wind affected terrain.>Be alert to conditions that change with elevation.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

Deep and destructive persistent slab avalanches may remain a concern in high elevation terrain (especially in the north of the region) as the snowpack adjusts to recent heavy storm loading.

Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>Be wary of slopes that did not previously avalanche - even on low angle terrain.>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

3 - 5

Valid until: Jan 29th, 2016 2:00PM