Violent microburst sends mud flowing from burn area

Downpour drops hail in San Dimas and sends mud into Glendora

A microburst of heavy rain, along with hail and lightning, pummeled parts of Southern California early Friday and sent 4 feet of mud into a Glendora home.

Mud swept through parts of Glendora, the foothill community scorched by the Colby fire in January, after a large cold-air storm cell dumped a quarter-inch of rain in three minutes about 2 a.m., according to the National Weather Service.

“North end of Glendora experienced a micro burst storm starting at about 0211 am," Glendora police posted on Facebook.

"Twelve minutes later, the mud came down into Glendora from the mountains," said weather service meteorologist Todd Hall.

The sudden downpour prompted the weather service to issue a flash-flood warning for the area burned by the Colby fire, he said. Residents were advised to shelter in place until 4:15 a.m.

Mud swept through Easley Estates, a gated community in Glendora, and at least one home sustained significant damage when 4 feet of mud flowed through the home in the 1100 block of Easley Canyon Road.

Police said crews were working to clean up mud and rocks from streets, but it would likely take several hours. Meanwhile, police, fire and public works crews plan to check roads for damage, according to the Glendora Police Department.

The weather service explains a microburst is a "downdraft in a thunderstorm less than 2.5 miles in scale" that can cause as much damage as a tornado -- or more. Some may threaten life and property, but all pose a real threat to aviation.

The system also brought isolated thunderstorms that were mostly concentrated on the San Gabriel Valley and foothills. Some parts of San Dimas were pelted with pea-sized hail, and snow fell as low as 6,500 feet, Hall said.

By 5 a.m., most of the storm had moved out of the region, and the weather is expected to clear up completely by Friday afternoon, Hall said.

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Copyright © 2016, Los Angeles Times

UPDATED

7:45 a.m.: This post, originally published at 6:38 a.m., was updated to add new details.

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