Avalanche Forecast

Fair - Due to variable snopack conditions

There may be a couple of cms of new snow overnight Tuesday into Wednesday morning. The ridge of high pressure should re-build early Wednesday bringing gradually clearing skies to the region. Thursday and Friday 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. 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.

It is always important to know the history of the snowpack in the area that you want to explore. This season presents some challenges developing this baseline information due to the snow arriving well before most observers have started working in the field. It may be wise to take the time to dig down deep and see what the basement looks like in your regular play areas. We have dropped the danger rating in the alpine to moderate. It is still likely that you could trigger a windslab in steep terrain. Triggering a full depth release is getting less likely, but weak spots are sure to exist that may propagate a large avalanche. The snow pack is still relatively young and needs some time to mature.

I wrote this on Monday, but I am going to leave it in here again today. There is not much change taking place. Previous problems are healing slowly, and I don't think it is cold enough to cause much facet growth in the base layers. We suspect that surface hoar may be growing during the clear cold weather that has dominated over the past few days. Some steep south facing slopes may have developed a thin sun-crust. Windslabs continue to be a concern in the Purcells. Strong winds last week developed unstable slabs of transported snow on steep terrain in the alpine and at treeline. Snow depths are quite variable through the region. In the alpine there is 170- 250cm. At treeline there is anywhere from 130-150cm.The upper snowpack is tightening up forming a stronger mid-pack. A highlighted concern for the Purcells was the mid-November storms that created a heavy slab over a weak basal faceted base, resulting in a significant cycle of large avalanches running full depth.