Scientists have finally solved the mystery of a milky rain that coated cars and raised eyebrows across a wide swath of the Pacific Northwest this February, researchers said on Tuesday.

A multidisciplinary Washington State University team said they had determined that dust from the dry bed of a shallow lake some 480 miles (772 km) from where the rain fell was to blame for the unusual precipitation.

The rain left a trail of powdery residue across a nearly 200-mile (322-km) stretch of eastern parts of Oregon and Washington state earlier this year, leaving scientists and residents perplexed about its origins.