Avalanche Forecast

Issued: Nov 23rd, 2012 8:40AM

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

triley, Avalanche Canada

Cariboos.

This bulletin is based on limited data. Local variations in conditions are likely to exist. Check out the forecasters blog for further details on interpreting early season bulletins.

Summary

Confidence

Poor - Due to limited field observations for the entire period

Weather Forecast

Overnight and Saturday: Cooling trend behind the storm as High pressure moves into the region, freezing level at valley bottoms. Expect -10.0 in the alpine. Winds should clock to the NW. No precipitation expected.Sunday: Should still be under the influence of the High pressure. Cooler temps and light winds.Monday: Continued High pressure.

Avalanche Summary

We have a report from the Valemount area ofÂ a snowmobile triggering a size 2.0 avalanche that was about 70 cm deep and about 80 metres wide. See photo here. The avalanche was triggered from a shallow weak area, and suspect that the weak layer was either the November crust or buried surface hoar. Please send us an email if you have any observations.

Snowpack Summary

Reports show that the region has had between 20-40 cm from the recent storm. Near Valemount the HS was 145 cm at 1975 metres during the storm. The foot penetration was 60 cm, so there is quite a bit of snow available now for transport by the strong winds during the day Friday and forecast for Friday night. The November rain crust was found down 100 cm and has been described as a weight bearing crust. There may also be a thin buried surface hoar layer down about 70 cm in the alpine. Buried persistent weak layers may become reactive with the recent storm loading.

Problems

Storm Slabs

The new storm snow and wind are expected to develop new slabs that may not bond well to old wind affected surfaces.

Travel on ridgetops to avoid wind slabs on slopes below.>Avoid freshly wind loaded features.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 5

Persistent Slabs

There are reports that the early November crust is also in this region. There may not have been much snow on the ground except in the high alpine when this crust formed. The new storm load may cause this layer to become reactive.

Carefully evaluate and use caution around thin snowpack areas.>Be aware of thin areas that may propagate to deeper instabilites.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 5

Valid until: Nov 24th, 2012 2:00PM