Spokane - Rainfall described as milky-colored, dusty or dirty fell across parts of Washington, Oregon and Idaho, with its origin is unclear.

The National Weather Service received reports of the dirty rain from more than 15 cities from Hermiston, Ore., to Rathdrum, Idaho, on Friday. The weather service's Spokane office collected water samples that will be sent to a lab for testing.

The light gray dirt in the rainfall coated vehicles and windows across the region as a rainstorm that originated in the Pacific moved in.

Dirty Rain
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Experts said they are checking out several possible explanations including a recent volcanic eruption in Mexico and one in Russia. The weather service said the rainstorm may have passed through some dust or volcanic ash as it moved west.

Walla Walla County's emergency management staff posted a statement on its Facebook page that the ash is likely from Volcano Shiveluch in Kamchatka Krai, Russia, some 3,000 miles away. Volcano Shiveluch spewed an ash plume about 22,000 feet high in late January, the statement said.

However, the county cautioned the source of the dirty rain has not been scientifically confirmed and that there are a number of volcanoes currently active.
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© FacebookWe had many reports of a "dirty" or "milky" rain
CNN meteorologist Derek Van Dam, meanwhile, pointed to an eruption Wednesday of a volcano in southwestern Colima, Mexico, as another potential source of the dirty rain. That volcano is more than 2,000 miles away from the region.

Meteorologists said it may be a while before they figure it out because nothing is showing up on satellite. However, that is not uncommon with these thick clouds and moisture.

Contributing: Katharine Lackey, USA TODAY; the Associated Press