Travel in avalanche terrain is not recommended today. At the mid and upper elevations dense slabs may release naturally and will be easily triggered by humans. Winds slabs, deep persistent slabs and wet avalanche issues are possible today. Avalanches originating in the upper elevations hold the potential to run long distances and cross one or more elevation bands. It will be critical to know the terrain above you and plan your travel accordingly. In the low elevations warm temperatures and occasional rain have created unstable conditions where wet avalanches are possible.
Recent snowfall from the last four days, very strong winds and warming temperatures over the past 24 hrs have created upside down conditions in the mid and upper elevations. Additional snowfall and more importantly very strong winds will add to this problem today. Slabs will range from 1-4 feet in depth. Expect more recently formed slabs to release naturally and be very sensitive to human triggers.
Weak layers of snow now buried between 4-8 feet deep have been stressed and tested over the last four days. Whether or not these layers have reached the tipping point is not clear. Due to the severe consequences of involvement in an avalanche of these depths, the best approach to this uncertainty is avoidance. These avalanches could be initiated by a newer slab, by the weight of a single person or may require a larger trigger.
The storm that lasted several days will exit the forecast area tomorrow as high pressure builds over the region. Cloud cover will lessen throughout the day from mostly cloudy to partly cloudy, and snowfall should taper off by mid-morning. In wake of today’s cold front, temperatures will cool into the single digits to low teens in the mountains and upper teens to twenties in the valleys. Westerly ridgetop winds are expected to be 15 to 20 miles per hour with gusts into the twenties. For tomorrow, the hazard rating is expected to be Considerable and avalanche conditions remain dangerous. The hazard rating will slowly decrease as snowfall comes to an end and winds lessen. That being said, natural avalanches are still a possibility and human-triggered avalanches are likely.Recent snowfall and strong winds have formed new surface slabs on leeward slopes and added stress to deeply buried weak layers. Avalanche activity on the December 5 interface, after this most recent loading event, is a reminder of the persistent nature of this layer. Slab depths could be up to 10 feet, although these slides are more likely to be triggered from areas where the slab is thinner. In managing this avalanche problem, it is important to stay out from under avalanche terrain and avoid avalanche runouts.
