Avalanche Forecast

Issued: Nov 26th, 2014 9:00AM

The alpine rating is high, the treeline rating is high, and the below treeline rating is moderate. Known problems include Storm Slabs and Loose Dry.

rbuhler, Avalanche Canada

Cariboos.

Winter storm conditions have produced a dangerous storm slab which sits on a touchy weak layer. Now is a good time to avoid avalanche terrain and stick to low angle slopes.

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

A warm, moist Pacific storm will continue to bring moderate-heavy precipitation to the southern interior on Thursday. The Cariboo region will receive the precipitation but is not expected to see a spike in temperatures like the south. An Arctic high pressure system should arrive on Friday morning bringing cold, sunny conditions for the weekend. Weds. Night/Thursday: Precipitation 25-35mm, treeline temp around -5, ridgetop wind moderate-strong SWThurs. Night: Precipitation 10-20mm, ridgetop wind moderate-strong SWFriday: A mix of sun and cloud, light flurries possible, treeline temp around -15, ridgetop wind easing during the daySaturday: Mostly sunny, treeline temperature around -20C, ridgetop wind light NE

Avalanche Summary

We haven't had any new reports since the weekend. If you have any observations, please send them to forecaster@avalanche.ca. On Saturday, several small natural avalanches were observed in the Raft Mountain area. Recent observations from the Rogers Pass area where the conditions are expected to be similar include widespread natural activity up to size 3.

Snowpack Summary

As much as 1 m of recent storm snow sits on the mid-November drought layer (facets, surface hoar, and/or a sun crust on steep southerly slopes). 20-30cm below this layer is a thick rain crust with weak facets on top. Snowpack data from the Cariboo region is very limited at the moment but I expect these layers are reacting similarly to the North Columbia as the formation conditions were generally the same. In the Rogers Pass area, the storm slab is poorly bonded to the mid-November layer and snowpack tests suggest it can be triggered easily with wide propagations possible. In some tests, the deeper crust/facet layer was also failing and it is possible that avalanches may step down to this layer.Recent strong and variable winds have probably created dense wind slabs in exposed terrain and resulted in variable snow distribution. At lower elevations, expect travel to be difficult and potentially hazardous as many early season hazards are exposed or lightly buried (stumps, logs, rocks, open creeks, etc).

Problems

Storm Slabs

The storm slab sits on a touchy weak layer and is expected to become very reactive with additional storm loading. Recent wind loading has created wind slabs in leeward features which are expected to be very touchy.

Be alert to conditions that change with elevation.>Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

3 - 5

Loose Dry

Be cautious of loose sluffing from steep terrain as new snowfall continues.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Be cautious of sluffing in steep terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Nov 27th, 2014 2:00PM