Avalanche Forecast

Issued: Jan 20th, 2017 4:40PM

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

shorton, Avalanche Canada

Northwest Inland.

Uncertainty about how deep persistent slabs will react to the recent snow and rain warrants a conservative approach to terrain.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

SATURDAY: Cloudy with isolated flurries, moderate southeast winds, alpine temperatures around -8.SUNDAY: Mix of sun and cloud with some isolated flurries, light southeast winds, alpine temperatures around -8.MONDAY: Clearing with a mix of sun and cloud, light west winds, alpine temperatures around -10.

Avalanche Summary

On Thursday, loose dry avalanches were reported in the alpine and loose wet avalanches were reported below treeline. Storm slabs sitting on a weak layer of surface hoar and/or a crust are likely easy to trigger at higher elevations. Full depth avalanches will continue to be a concern for some time due to the weak faceted lower snowpack.

Snowpack Summary

Last week's storm delivered 20-30 cm in the Smithers area and 40 cm or more in deeper areas to the north and west. Freezing levels reached up to 1600 m, leaving moist surface snow which is now freezing into a crust. Storm slabs may be lingering at higher elevations and may sit on a weak layer of surface hoar and/or old hard wind slabs. Most areas continue to have a shallow and weak snowpack that is about 120-150 cm at treeline. In general, the lower snowpack consists of old hard wind slabs above weak faceted snow.

Problems

Deep Persistent Slabs

Recent storm snow combined with warming and wind has loaded hard slabs above a weak faceted base. Uncertainty revolves around what type of load is now required to trigger these deep persistent slabs.

Stick to simple terrain and be aware of what is above you at all times.Be aware of the potential for full depth avalanches due to weak layers at the base of the snowpack.Avoid steep convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3

Storm Slabs

Recent snow, warming, and strong winds have created storm slabs at higher elevations. Storm slab avalanches in motion may step down and trigger deep persistent slab avalanches.

If triggered the storm slabs may step down to deeper layers resulting in large avalanches.The new snow will require several days to settle and stabilize.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Jan 21st, 2017 2:00PM