The conditions that led to fatal avalanches in the Washington Cascades could get worse this week. Three expert skiers died near Stevens Pass on Sunday and a snowboarder died in a separate avalanche near Snoqualmie.
Mark Moore is the director of the Northwest Weather and Avalanche Center. He says a crystalline layer of frost prevented new snow from bonding with the bottom layers. He estimates that led to hundreds if not thousands of avalanches in remote areas over the weekend.
Moore says heavy rain in the forecast will only increase the weight of the top layer.
“You're putting a stack of books on the side of a hill," Moore explains. "Put some potato chips in there somewhere too and you can see how the mass of the overlying books will help to crush the potato chips and also give it a nice sliding surface to release on.”
Weather fluctuations this winter have created unstable conditions farther east as well -- in the Rocky Mountains and Intermountain West. In north Idaho, the dry start to winter made for a weak snowpack. An avalanche technician in the Idaho panhandle says as the upper levels of snow melt, that unstable base could cause problems for back country skiers.
February and March are often the worst months for avalanches in the Northwest.
