South Columbia

We are dealing with a complex avalanche scenario. There is uncertainty in how buried weak layers will adjust to the warm temperatures. Conservative decision making is still recommended.

Fair

Freezing levels are forecast to remain high through Monday (up to 3300m) before gradually falling over Tuesday and Wednesday. Winds will be light to moderate from the south west with a possibility of showers and/or flurries at higher elevations on Tuesday.

We are moving into a complex avalanche scenario where touchy conditions are likely to persist.  A snowpack with several critical avalanche layers has seen incremental loading in the form of new snow and more recently rain.  Two recent avalanche cycles have produced increasingly large avalanches primarily on the mid-January surface hoar layer. While the region will see little to no precipitation through the coming forecast period, I anticipate that natural avalanches will remain possible and human triggered avalanche likely as the upper snowpack adjusts to the warm temperatures.  Avalanche danger will be higher on slopes exposed to the sun.  Warming temperatures will also make cornices more likely to collapse, which in turn could be sufficient to trigger a deep slab avalanche.  I would be wary of overhead hazard. At lower elevations I suspect there is the potential for loose wet and wet slab avalanches.

Warm temperatures are encouraging the recent snowfall to rapidly settle into soft slabs.  Below 1800m this snow may sit on a thin crust.  Moderate to strong southwest winds have created wind slabs in lee features.  A weak layer of surface hoar above a crust buried mid-January lies between 40 and 70 cm below the surface.  This layer has been responsible for the majority of the recent avalanche activity and I suspect that we will see it continue to produce avalanches as the snow pack adjusts to the recent snowfall and continued warm temperatures. The mid-December surface hoar/crust layer is now typically 80 to 140cm below the surface and remains a concern. While snowpack tests indicate this layer is gaining strength in many areas, avalanches were stepping down to this layer during the last storm  suggesting that it should continue to factor  into our decision making process. I suspect that it remains mainly a concern on open slopes at and just below treeline.