Columbia Valley Dust Cloud

February 16, 2008


Provided and copyright by: Susan Freiberg
Summary authors & editors: Susan Freiberg

While finishing up a project late in the afternoon of September 7, 2007 north of Wenatchee, Washington, a colleague and I watched a dark cloud-mass move into the Columbia Valley off the Waterville Plateau toward the east. A strong north wind had been blowing all day, so we thought this odd. It looked like rain, but saw no rain columns. A wildfire? We saw no smoke. Then we realized it was dust! The cloud dissipated quickly after reaching the Columbia River and Wenatchee. According to the September 8, 2007 Wenatchee World, forecaster Mike Fries reported that a cold front coming over the Waterville Plateau carried dust from the Okanogan Valley into the Wenatchee Valley. A weather spotter in the town of Hartline, about 50 miles (80 km) east of Waterville, noted visibility of less than a 1/4 mile (about 1/2 km) and sustained winds of at least 25 mph (40 k/ph) at about 1:30 p.m. (local time). The weather service did not classify it as a dust storm, though by definition, a dust storm includes a large area with visibility less than a 1/4 mile and sustained winds of 25 mph (40 k/ph) or more.

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