After heavy rain, elevated freezing levels, and strong Southeasterly winds the hazard rating has risen to high for Douglas Island. Two large natural avalanches were reported on Showboat as well as many others around town. With more rain expected throughout the day human triggered and natural avalanches are likely, dangerous avalanche conditions exist on all aspects and elevations.
Wet slabs occur during rain on snow events, they can propogate widely and are often hard to predict timing wise due to the time it takes rain water to percolate through the snowpack and weaken the bond between the slab and underlying weak layer. After all the rain to our highest elevations this problem is present at all aspects and elevations.
Layers of faceted snow grains are still present in many locations. These faceted layers are generally deep in the the snowpack and exist in middle and upper elevations. Rain will continue to stress these layers making large persistent slab avalanches possible.
Wet loose avalanches will be likely today on steep middle and lower elevation terrain. Wet Loose avalanches can start small but rapidly entrain snow and grow in size. Avoid steep gulleys and confined chutes that can act as terrain traps during wet loose avalanches.
There are multiple avalanche problems to contend with today as an atmospheric river affects the region this weekend. While precipitation intitially started as snow early Friday morning, it rapidly warmed causing a transition to rain to upper elevations by mid day. The rain and warming quickly decreased the stability of our snow pack and several large natural avalanches were reported both on Douglas Island and the Juneau main land on Friday. With continued warm temperatures and rain forecasted the avalanche hazard will remain elevated today. As liquid water works its way through the snow pack, wet loose and wet slab avalanches are likely. The stress of extra loading from rain saturated layers in the snow pack could also overload persistent weak layers that are deeply buried in some middle and upper elevation locations making large persistent slab avalanches possible as well. The CBJ and AKDOT have both published public avalanche advisories for the urban and highway avalanche hazards around the Juneau community. We encourage the public to continue to check these advisories to stay informed as conditions change.
