In late December 1964, as the Mountain was preparing for Christmas, the weather in the upper Sandy River valley began to shift quickly. A warm Chinook wind swept into the region, accompanied by days of heavy rain, melting a deep early-winter snowpack, while frozen ground prevented the water from soaking in. Creeks rose first, then the rivers. By the time people realized how serious it was, the water was already moving fast and carrying things with it — logs, boulders, and ent