Powerful winds and rain will sweep across Southern California on Thursday, bringing the potential for dangerous mud flows in the foothills of Los Angeles and San Bernardino counties, the National Weather Service said.

Starting early Thursday in San Luis Obispo and Santa Barbara counties, the storm will spread southeast across Los Angeles County and the San Gabriel Mountains, where it’s expected to drop 1 to 3 inches of rain by Friday morning, meteorologist Joe Sirard said.