Avalanche Forecast

Issued: Nov 30th, 2015 9:19AM

The alpine rating is below threshold, the treeline rating is below threshold, and the below treeline rating is below threshold. Known problems include Wind Slabs and Deep Persistent Slabs.

ghelgeson, Avalanche Canada

Cariboos.

A big change in the weather is headed our way. Visit avalanche.ca/weather for more details.

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

Bottom Line: The weather is changing, the inversion should be cleared out by Tuesday morning. The coast will likely get hammered as a digging upper trough makes landfall over the next few days. Some of the snow and southerly winds associated with this event are expected to spill over into the Cariboos. At this point amounts and timing are too dynamic to pin down, but the region should see 5 to 15cm of snow Tuesday night, with an additional 5cm Wednesday. Strong SW winds are expected throughout the region beginning Tuesday night. The freezing level should remain at valley bottom through Tuesday night. Its expected to climb to around 1500m Wednesday before returning to valley bottom Wednesday night. The pattern looks similar for Thursday with the freezing level once again rising to around 1500m. For detailed mountain weather information visit: avalanche.ca/weather.

Avalanche Summary

No reports of avalanches in the Cariboo region from the last few days. If you have observed any, please share your information through the Mountain Information Network.

Snowpack Summary

The snowpack is extremely variable at this time, with wind scoured North facing slopes at treeline and above. South facing slopes have wind slabs at tree line and above and may be hiding surface hoar from the previous spell of cold clear weather. Surface facetting has observed in the region as a result of the recent cold weather and clear skies, and surface hoar as large as 40mm has been reported building in sheltered locations below tree line. There are a number of surface hoar layers now buried in the snowpack that seem to be unreactive, with the most recent having been buried on Nov 24th. In shallow snowpack areas, especially on northern aspect, there is a weak facetted layer at the base of the snowpack. Warming temperatures and strong solar radiation over the weekend has left a crust on solar aspects.

Problems

Wind Slabs

Previously strong north winds formed wind slabs that extend from treeline to just below ridge crest. Most of these wind slabs are probably old, tired and hard to trigger, but there may be a few that remain sensitive to human triggering.

It's best practice to use ridges or ribs to avoid pockets of wind loaded snow at this time.>Be cautious as you transition out of wind sheltered terrain and >avoid features that are actively being wind loaded.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Deep Persistent Slabs

We suspect that this is really only a problem on high elevation north facing features where weak faceted snow *may* exist at the base of the snowpack.

You can manage this problem by avoiding likely trigger locations in the alpine like rock outcroppings, convexities and places where the snowpack goes from thick to thin.>

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Unlikely

Expected Size

3 - 6

Valid until: Dec 1st, 2015 2:00PM