Avalanche Forecast

Issued: Nov 27th, 2016 4:04PM

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

Avalanche Canada cgarritty, Avalanche Canada

Recent snowfall and wind have heightened avalanche danger in the region. Make conservative decisions and wait for the snowpack to stabilize.

Summary

Confidence

Moderate -

Weather Forecast

Up to another 5cm of new snow is forecast to fall in the South Columbia mountains by Sunday evening as light winds shift to the west. Freezing levels will begin a downward trend on Monday. Only trace amounts of new snow are expected for Monday while Tuesday will see cloud cover decreasing and winds shifting to the northwest.

Avalanche Summary

Stormy weather prevented observations at alpine elevations, but new snow was observed sluffing up to size 1 at treeline and below on Saturday, in addition to skier triggered size 1 and natural size 2+ avalanches reported in Rogers Pass on Saturday. Explosives control in the Revelstoke area on Friday also yielded numerous size 2 results with slab thickness reaching up to 80cm in depth. Danger from storm slab avalanche activity is expected to persist while new snow undergoes settlement.

Snowpack Summary

Up to 25 cm of new snow fell on Saturday under moderate to strong southerly winds. This new snow now covers the already touchy storm slabs that existed in exposed areas at treeline and above. On solar aspects these slabs have been reactive above a sun/temperature crust which formed on November 22 and can be found 30-50cm deep in the snowpack. The thick, widespread November 13 crust now lies up to a metre below the surface. Below this crust the mid and lower snowpack are well consolidated, with moist snow present at treeline and below. Isothermal snow can be found at the base of the snowpack.

Problems

Storm Slabs

An icon showing Storm Slabs
A heavy snowfall on Saturday has increased the destructive potential and likelihood of triggering storm slab avalanches, especially in exposed lee terrain. Fresh load on the snowpack has also increased the potential to trigger deeper instabilities.
The new snow will require several days to settle and stabilize.Use ridges or ribs to avoid pockets of wind loaded snow.Use caution in lee areas in the alpine and treeline. Recent storm snow has formed touchy slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 3

Valid until: Nov 28th, 2016 2:00PM