Avalanche Forecast

Issued: Jan 22nd, 2013 10:05AM

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

Avalanche Canada slemieux, Avalanche Canada

Danger ratings are based on snowfall starting early Wednesday. If it starts later, they would be one step too high for Wednesday.

Summary

Confidence

Fair - Timing of incoming weather is uncertain on Wednesday

Weather Forecast

Tuesday night and Wednesday: The frontal system is pushing its way into the interior and precipitation should start around Wednesday morning. 10 to 15 mm (possibly more in W and S of region) is expected to fall during the day with moderate to strong winds from the SW in the alpine. Freezing levels will lower to valley bottom and the inversion will disappear. Thursday: A break before the next system. Expecting some clearing, winds tapering off staying from the same direction, temperatures also staying cool and freezing level to valley bottom.Friday: Expecting light precipitation and moderate SW winds.

Avalanche Summary

Numerous moist loose avalanches up to size 1.5 and snowballing on S facing slopes was reported.

Snowpack Summary

Storm snow accompanied by strong SW-W winds will create loose snow concern in sheltered areas and new wind slabs in the alpine and at treeline on lee slopes. These new layers will most likely be touchy for a certain time and could also put on the needed load to awake the deeper instabilities that have been unreactive to skier traffic lately. The new snow will be sitting on a variety of surfaces; sun crust on S facing slopes, surface hoar layer mostly found in shaded-sheltered areas below treeline, facets and old windslabs that were breaking down. The early January surface hoar layer found under the top 50-70 cm, which has been unreactive to skier traffic but still producing the odd sudden planar shears especially under the elevation of 1500 m. in sheltered areas, could become more reactive with this added load. Under these concerning layers, a strong mid-pack overlies a weak facet/crust layer near the base of the snowpack, which is now considered inactive. 

Problems

Storm Slabs

An icon showing Storm Slabs
Storm snow might not bond to a variety of surfaces. New windslabs will form as the day goes on lee side of the forecasted strong SW-W winds in alpine and at treeline.
Be extra cautious in avalanche terrain during periods of heavy loading from new snow and wind.>Avoid areas where sluffing may have severe consequences.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 5

Persistent Slabs

An icon showing Persistent Slabs
The load from the storm snow could awaken the early January surface hoar layer. Distribution is patchy in sheltered areas and has been more reactive on S and SW aspects.
Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Glide cracks have been active lately, give them a wide berth.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 5

Valid until: Jan 23rd, 2013 2:00PM