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National Scientists, Weather Service Dig Into Mystery Of Milky Rain

National Weather Service
Scientists are still trying to determine what was behind the 'milky rain' that fell on eastern Washington and Oregon last week.


Scientists don't yet agree on the cause behind the dirty rain that pelted much of eastern Washington and Oregon last Friday.

The National Weather Service said the dirt may have come from southeast Oregon, near Summer Lake. But another government scientist says he thinks it was ash from a volcano in Japan.

Scientists say dust or muddy rain events aren’t really rare, but this 200-mile event with gunk dropped from Spokane to Fossil, Oregon is unusual.

A group of atmospheric scientists from the Pacific Northwest National Laboratory in Richland, Washington intend to study the muddy rain this week. They have a theory that the sediment is ash from a Japanese volcano.

Credit National Weather Service
National Weather Service
Locations of reports of milky rain on Feb. 6, 2015.

Another group that includes a University of Washington scientist and the Benton Clean Air Agency also intends to test samples. They think the sediment might be from a southeast Oregon lake, a recently burned area in Oregon or possibly even Nevada dust.

A Washington State University meteorologist weighed in with his analysis Tuesday. He also thinks the dust is probably from an ancient lake in Oregon.

The National Weather Service also has a sample, but says it won't test it. The agency posted a picture of a jar of cloudy water taken at the Spokane station on its social media sites.

Several scientists have made offers online to test material from the event, but a weather service spokesman said the sample was likely contaminated. He said it had been dumped into several non-sterile jars and that the whereabouts of the sloshy sample over this past weekend couldn’t be accounted for.


Anna King calls Richland, Washington home and loves unearthing great stories about people in the Northwest. She reports for the Northwest News Network from a studio at Washington State University, Tri-Cities. She covers the Mid-Columbia region, from nuclear reactors to Mexican rodeos.