Avalanche Forecast

Issued: Jan 25th, 2013 10:02AM

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

Avalanche Canada slemieux, Avalanche Canada

Summary

Confidence

Fair - Wind speed or direction are uncertain on Sunday

Weather Forecast

Friday night and Saturday: A bit of a precipitation break with moderate winds with strong gusts from the NW friday night. Another unsettled air mass will bring more precipitation on the region on Saturday but no significant amounts. Light W winds gusting moderate in the afternoon and surface freezing level and seasonal temperatures in the alpine (-5 to -10 C). Sunday: Similar pattern with more precipitation on the W and NW Columbias, light to moderate W winds, cooler temperatures (down to -12 C). Monday: Arctic front tracking towards the region bringing more light to moderate precipitations and even cooler temperatures.

Avalanche Summary

A small natural avalanche cycle took place in the storm snow up to size 2 which ran on the January 23rd interface mostly on N and E face. Multiple loose and slab avalanches were also skier triggered in the new snow up to size 1.5 also on the January 23rd interface on various aspects but mostly NE and E aspects.

Snowpack Summary

Around 40 cm fell with the last 2 systems (more W and a little bit less in other parts of the region) with light to moderate S-SW winds in the alpine and with relatively warm temperatures at low elevations.  Storm slabs are found at all elevations. In the alpine, it is expected that the bond between these slabs and the underlying surface will improve, however they could also gain propagation potential with the continuing settlement. In other words, they could become harder to trigger, but if triggered, they will generate bigger avalanches. The new snow is also sitting on a couple of weak layers; a suncrust on S facing slopes and on a surface hoar layer mostly found below treeline. The bond of the new snow with these layer is now weak and it usually takes longer to improve and is harder to predict. It is therefore important to keep monitoring their location and reactivity to ski and snowpack tests. The early January surface hoar layer down 60-80 cm, also in the below treeline band, is becoming less of a concern to professionals. It has been producing a variety of snowpack results (from break to sudden planar) but has not been reactive to skier traffic in a while.

Problems

Storm Slabs

An icon showing Storm Slabs
Expect to find soft wind slabs on lee ridges of W-SW winds in the alpine and treeline. Storm slabs are also present in sheltered areas at treeline and on all aspects below treeline. If triggered, it could step down to a deeper weak layer down 80 cm.
Choose well supported terrain without convexities.>Avoid steep open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Sluffs may trigger deeper instabilities.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 5

Valid until: Jan 26th, 2013 2:00PM

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