Avalanche Forecast

Issued: Nov 30th, 2017 4:12PM

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

jlammers, Avalanche Canada

Cariboos.

This forecast is based on very few field observations and a high level of uncertainty exists. A conservative approach to terrain selection is critical until more snowpack data becomes available.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Friday: 5-10cm of new snow / Strong southwest winds / Freezing level at 900mSaturday: Light flurries / Light and variable winds / Freezing level at 400mSunday: Mix of sun and cloud / Light and variable winds / Freezing level at valley bottom with alpine temperatures dropping to about -13

Avalanche Summary

No new avalanches were reported in this region. This may speak to a lack of observations rather than actual conditions. With recent wind and snowfall, a natural storm slab avalanche cycle is expected to have occurred on Thursday. Human triggering of these storm slabs is expected to continue into the weekend.We currently have very limited observations from this region. Please submit your observations to the Mountain Information Network (MIN).

Snowpack Summary

Up to 40cm of new snow has fallen in the past few days. At higher elevations, southerly winds (gusting strong at times) likely redistributed the new snow, forming wind slabs on lee features.Below the recent storm snow you may find a couple of crusts which formed as a result of last week's rain. That said, little is known about the reactivity of these crusts or the elevation bands at which you're likely to find them. A major feature in the snowpack is a crust which formed around November 11th and can be found approximately 100cm down at treeline elevations. We currently have very limited snowpack observations within this region and it is critical to supplement this information with your own observations.The depth of the snowpack varies greatly with elevation. Recent reports suggest the average depth is 200+cm in the alpine, 100-160cm at treeline, and decreasing rapidly below treeline where the primary hazards are rocks, stumps, and open creeks.

Problems

Storm Slabs

Recent wind and snowfall has likely formed touchy new storm slabs. Storm slabs may more reactive than expected in wind-exposed terrain, or in areas where underlying crusts remain reactive.

Be cautious as you transition into wind affected terrain.The new snow may require several days to settle and stabilize.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

Not much is known about the reactivity of a hard crust which lurks deep in the snowpack. This uncertainty warrants conservative terrain selection as an avalanche at this interface could be large and destructive.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Dec 1st, 2017 2:00PM