Avalanche Forecast

Issued: Dec 5th, 2016 4:11PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs.

Avalanche Canada mbender, Avalanche Canada

Lingering wind slabs from this weekend's storm will continue to be reactive. Caution as you transition into wind exposed terrain.

Summary

Confidence

Low - Due to the number of field observations on Monday

Weather Forecast

An Arctic front continues to push southward on Tuesday bringing cold, dry conditions for the next few days. A mix of sun and cloud is expected on Tuesday with light alpine winds from the northeast and tree line temperatures around -18C. Conditions are expected to remain similar on Wednesday and Thursday as the arctic air continues to dominate the weather pattern.

Avalanche Summary

Natural storm slab and wind slab avalanches up to size 2.5 were reported in the region through the weekend. These were typically 25-50cm thick and were mainly occurring on north and east aspects in the alpine and at treeline. The new snow that fell over the weekend has been redistributed by the wind primarily onto north and east aspects in the alpine and at tree line. These wind slabs are expected to be reactive for the next few days. Isolated persistent slab avalanches on the mid-November crust will remain an ongoing concern and appears to be a low probability, high consequence problem which likely would require a heavy trigger or triggering from a thin area.

Snowpack Summary

The weekend storm system typically brought 40-70cm of new snow to the region with strong southwest wind in the alpine. The wind has redistributed the storm snow into leeward features in wind exposed terrain. In some areas, the recent storm snow may sit over a layer of small surface hoar. There is some uncertainty regarding the distribution of this surface hoar in the region but it was reported in a couple locations in the Monashees west of Revelstoke. The mid-November crust is now typically down 1-1.5m in the snowpack. Test results on this layer have been highly variable ranging from sudden and easy to unreactive. While there has not been much avalanche activity on this layer yet, it has many professionals concerned. It will be important to track how this layer evolves, especially with the upcoming period of cold weather. Below the crust the snowpack is generally well settled and is reported to be moist at lower elevations. The snowpack depth tapers off substantially below around 1700m elevation and many early season hazards are still a concern.

Problems

Wind Slabs

An icon showing Wind Slabs
Recently formed wind slabs are expected to be reactive to human triggering.
Be cautious as you transition into wind affected terrain.Use caution in lee areas. Recent wind loading have created wind slabs.Dig down to find and test weak layers before committing to a line.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 6th, 2016 2:00PM