Avalanche Forecast

Issued: Jan 7th, 2014 8:32AM

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

Avalanche Canada slemieux, Avalanche Canada

Summary

Confidence

Good

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 very light to light 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

Windslabs were triggered by a vehicle and by explosive control in the Eastern part of the region on an E facing aspect slopes. These avalanches were up to 1.5 in size and would have slid on older faceted surface or on low density new snow. A detailed incident report about the Corbin area near miss is available here.

Snowpack Summary

There are pockets of windslab on lee side of SE and SW winds below ridgetop in the alpine. The storm slab is settling but is still sensitive to human trigger, especially where a weak faceted snowpack is underlying that top fresh layer. The facet/crust layer down 80-100 cm at treeline and below treeline  and the depth hoar layer in the alpine seems quite reactive on E aspects. Multiple recent natural and human triggered avalanches on this aspect is a good sign of this instability. When tested and observed, the surface hoar layer down 70 cm is showing signs of healing (grains are rounding and snowpack test are not as planar as they used to be).  The South Rockies field team has posted a new blog with some good info and pictures about the recent avalanche incident and about current conditions. Click here to read it.

Problems

Wind Slabs

An icon showing Wind Slabs
Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>Avoid steep lee and cross-loaded features>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 4

Persistent Slabs

An icon showing Persistent Slabs
Depth hoar at base of snowpack and/or crust/facets combo layers down 100 cm could still be triggered by skiers and sledders. These layers seem more reactive on E facing slopes.
Avoid open slopes and convex rolls at and below treeline where the crust/facet combo or depth hoar exist.>Dig down to find and test weak layers before committing to a line.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 6

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