Avalanche Forecast

Issued: Jan 7th, 2014 8:34AM

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

Avalanche Canada slemieux, Avalanche Canada

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain on Thursday

Weather Forecast

Tonight and Wednesday: A weak system will pass through tonight and ease Wednesday morning. Expect light precipitation, Westerly winds switching from the SW with freezing levels at the surface. Thursday: As another system dives South into Washington Wednesday night, the region could see moderate amount of precipitation early Thursday and then easing off during the day. Winds should be from the W with freezing levels at the surface.Friday: The zonal flow is allowing another system to pass through but quantities are unsure as models do not agree on track and timing of the system. Freezing levels are forecasted to rise.

Avalanche Summary

A few natural slab avalanches size 1.5 occurred on E aspects in steep rocky terrain. Several skier and sled triggered avalanches up to size 2 around Nelson area on E and SE aspect in the alpine were also reported. Explosive control in the Kootenay pass area produced up to size 2 avalanches on N aspects in the alpine.

Snowpack Summary

The recents SW and NW winds created touchy windslabs on lee slopes and on crossloaded features in the alpine and at treeline. These windslabs will most likely still be reactive to skier triggering. Storm snow is settling well. At the surface in the below treeline elevation band, a sun crust exists on steep S aspects and surface hoar grew in shady areas.  Persistent weak layers (PWL) are still a concern to avalanche professionals. Multiple surface hoar layers located down 25cm, 40 cm and 90 cm are giving variable snowtest results and the facet/crust layer down 100 cm has given multiple sudden planar snowpack test results mostly on S aspects. The surface hoar layer down 90 cm would be more sensitive on N and NE aspects and the facet/crust layer would be more sensitive on S aspects. There is quite a variability throughout the region regarding the persistent weak layers. The Eastern half of the region area seems to be the most problematic.

Problems

Wind Slabs

An icon showing Wind Slabs
Windslabs located under ridgetops mostly on NE to SE facing slopes will be sensitive to skier triggering. 
Travel on ridgetops to avoid wind slabs on slopes below.>Use ridges or ribs to avoid pockets of wind loaded snow.>Dig down to find and test weak layers before committing to a line.>

Aspects: North, North East, East, South East, South, South West.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Jan 8th, 2014 2:00PM

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