The upper snowpack is becoming more supportive, allowing for better travel. The lower snowpack remains weak and unsupported. Conservative terrain choices are still a good idea.
Although strong/extreme W/SW wind is forecasted on Monday, there is little recent snow available for transport. Watch for wind-slabs in the immediate lee areas in the alpine.
The lower snowpack is comprised of weak facets and depth hoar with the upper snowpack forming a 40 to 90cm thick slab above. This weak basal layer is uniform across most of the forecast region and has been responsible for most of the avalanche activity to date this season.
On a weather station repair flight today, Visitor Safety observed a size 2 avalanche on the East side of Copper mountain. A cornice pulled a slab at 2700m which was 50cm deep by 30m wide and ran about 800m. Sunshine patrol reported triggering a couple of size 2's at 2300m with explosives that scrubbed down to the ground in areas that were previously uncontrolled.
10cm overlays a surface hoar /crust layer which is sporadic in the region. The Dec 17 surface hoar/sun crust layer is down 25-50cm, and generally not reactive. The Nov. 16 deep persistent layer is down 40-90cm and continues to produce sudden failures in snowpack tests. In Little Yoho, these two layers are deeper and more spread apart in the snowpack.
Expect an increase in wind from the NW into the extreme range on Monday. Following the wind, a small amount of snow is expected Monday night, but not more than a few cm's. Valley temps will be about -10 and the ridge will be about -15.
More details can be found in the Mountain Weather Forecast.
