Avalanche Forecast

Fair - Freezing levels are uncertain on Friday

Thursday, Friday, and Saturday are forecast to be mostly clear and sunny with freezing down to the valley at night and rising slightly above the valley during the warmest part of the day. The freezing level on Friday may rise up to about 1200 metres. These conditions are prime for surface hoar to develop and continue to grow. We may continue to develop sun crust on steep slopes in the alpine that are exposed to the sunshine. Winds should be light from the west, but we may see some moderate outflow winds from the north in the alpine.

There are no new observations of avalanches from this region. It has been about a week since we have had new snow in this area. The avalanche problems have been decreasing in likelihood, and the expected size has also been decreasing. I have decreased the avalanche danger at treeline to LOW, and have kept the danger rating in the alpine at MODERATE due to the likelihood of releasing an old windslab avalanche. There is still a chance of triggering a very large avalanche from a weak thin spot in areas with variable snowpack depth.

There is some chance that there will be an area of above freezing temperatures in the alpine on Friday. There is some warm air on the coast that may move inland far enough to effect the Cariboos. If the warm air does make it into this region, there may be a short period on Friday when the avalanche danger is higher than forecast. Surface hoar has been forming over the last few clear and cold nights. Expect to find a sun-crust that has formed in the alpine on south through west aspects. I expect that the surface hoar will no longer be present on aspects that have developed the sun-crust. Wind slabs persist in the alpine and in large openings at treeline. The windslab has become less reactive to human triggers; however avalanches up to size 2.0 are still possible due to this problem. Some areas have a rain-crust below treeline from the 28th of November that has been buried by about 20 cms of snow. This rain-crust may be developing facets, and could become a layer of interest after it is buried by more of a load. There is still some concern associated with the early November buried surface hoar layer. This layer is buried down about 100-150 cms. Tests are showing that this layer is getting harder to release, and less likely to give clean and fast shears (Sudden Planar). If an avalanche does release on this layer, it is likely to be very large and destructive. Some areas also have a weak layer of facets at the base of the snowpack.