South Rockies

We have a report of a large avalanche (size 3.0) triggered by a snowmobiler in the Mt. Corbin area last weekend. In short, it sounds like like some snow stiffened by the wind released down deep on the weak facets. If you have any observations from the field, please drop us an email: [email protected].

Fair - Due to variable snopack conditions

A ridge of high pressure builds back into the area Thursday and then dominates the weather pattern through the end of the work week. Winds will be at light to moderate speeds out of the NW all day Thursday. Freezing levels creep up to 900m before dropping back to the valley floor overnight. Temps are cool; I'm expecting daytime highs near -9 at treeline Thursday with overnight low's dipping down to -12. Friday looks to be more of the same.

We're off to a good start for early December with upper elevation snow depths that average a meter. It's been about 10 days since our last significant storm and since that time the snowpack has suffered an unrelenting barrage of wind from around the compass rose. Wind exposed terrain is now a mixed bag of wind effected snow that varies from old hard windslabs to fresh small windslabs and everything in between. To travel safely at & above treeline you need to be able to recognize and avoid these potentially dangerous windslabs. This is the first part of the avalanche problem. Folks with extensive experience and education should be able to manage this hazard.Getting a little lower in the snowpack reveals some ugliness. A raincrust sits above large striated facets (sugar snow) on the ground. This is the classic Rockies house of cards setup that professionals throughout the region are concerned about. While there hasn't been any activity reported on this layer for the last few days, the potential for large full depth avalanches remains a concern for backcountry travelers. Triggering an avalanche in this weak layer will result in a large & destructive avalanche that will likely be unsurvivable. This problem will not go away anytime soon. If I was putting together plans for the weekend I'd be combing through my terrain atlas (google earth) looking for slopes around treeline that are protected from wind. Once you're out in the field stay off of terrain features that are thin and weak. Rock's and/or tree's poking out of the snow are a good indication of thin weak snow. It's good practice to avoid terrain that is steep and rocky in general right now. Remember, it's only December and our snowpack needs some time to mature before we even start thinking about the bigger more committing terrain.