Avalanche Forecast

Issued: Dec 20th, 2013 9:26AM

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

jfloyer, Avalanche Canada

South Rockies.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

Very little precipitation in the forecast for this region. Saturday, Sunday, Monday: A chance of flurries each day, with light snow possibly starting to fall Monday afternoon. Treeline temperatures consistent around -10C. Ridgetop winds moderate from the NW, picking up a little on Monday afternoon.

Avalanche Summary

A few loose dry sluffs were observed on Friday. No Slab avalanches were reported.

Snowpack Summary

There appears to be a lot of snowpack variability across the region. Snowpack depths at treeline seem to vary from 50 - 110 cm with high variability in wind-exposed areas. There are several persistent weak layers which are still being discussed in the region. Nearest to the surface is the mid-December (~Dec 10) facet/surface hoar/crust interface which does not seem to have enough snow on it yet to create a widespread problem. Next is the late-November/early-December interface which is made up of surface hoar, a crust, and/or facets. This layer is typically down 30-70cm and is most likely to pose the biggest problem for the region at the moment. Check out this video of a recent snowpack test on this layer. Despite it's reactivity in snowpack tests, we have not yet seen widespread avalanche activity on this layer. I suspect it only needs a little more additional load to turn this into a more serious avalanche problem. A buried crust from mid-November can be found near the base of the snowpack below 1650 m and is breaking down into facets.

Problems

Wind Slabs

Mostly S and SW winds continue to develop wind slabs in the alpine and open areas at treeline.

Be cautious as you transition into wind affected terrain.>Be careful with wind loaded pockets. Be aware of wide variation in snowpack depth>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Persistent Slabs

The most significant interface is a layer of surface hoar from early December. This is buried 30-70 cm below the surface and is becoming more reactive in areas where the upper slab has become a little denser.

Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>Dig down to find and test weak layers before committing to a line.>Avoid shallow snowpack areas on steep, convex terrain where triggering is more likely.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Dec 21st, 2013 2:00PM