Southwesterly winds and temps will increase on Saturday making human triggered avalanches more likely. Models differ on snow amounts over the next few days but we may see between 10-40cm of snow by boxing day. This will be the first test of the weak facetted base layers.
Increasing winds tonight/tomorrow will build these new slabs in lee areas in alpine and treeline. It will likely step down to the deeper weak base layers.
This layer should be monitored as elevation is gained. Despite being labelled as deep, it can be a ways off the ground. Expect this layer to get worse with the incoming cold.
One new sz 2 avalanche was observed in Tent Bowl today that failed at 2700m on a NE aspect right at ridgeline in 40 deg terrain. The depth of the avalanche was only 30-40cm, 30m wide but the slide stepped down to ground and ran 200m
At treeline snowpack depths vary based on orientation to the winds. On average 110cm of snow is found at this elevation. The main concern is the Late November interface down 55cm that is failing as a sudden collapse in snowpack tests. Beneath this layer the snowpack is weak and facetted.
Overall the weak facetted base persists everywhere in the region. As soon as there is a cohesive layer over this weak base the potential for human triggering will increase. The cohesion is most likely due to winds as you reach treeline. Any avalanche that occurs (even if it initiates in the upper snowpack) is likely to step down to the weak basal facet layers and involve the entire snowpack.
As winds and temps increase over the next 48 hours, we expect the snowpack to become more sensitive to triggerring so choose conservative areas like we have been saying.
Temperatures are set to begin to increase over the next few days as the high pressure ridge that dominates the area begins to finally break down. As always, as temperatures rise up towards zero, winds will also increase... Expect winds to increae into the strong to extreme range out of the SW over the next 24hrs. In terms of snowfalls, models differ with regards to amounts Some models are calling for 40cm by boxing day while others are only calling for 5cm. So, as the system moves closer to our area pay attention to weather updates. Its safe to assume our current snowpack is weak and best and winds and snow are likely to push us towards an avalanche cycle.
More details can be found in the Mountain Weather Forecast.
