Rain falling on Southern California is expected to aid firefighters mopping up multiple wildfires. But potentially heavy downpours on charred hillsides could bring new troubles such as toxic ash runoff. Los Angeles County crews spent much of the past week removing vegetation, shoring up slopes and reinforcing roads in devastated areas of the Palisades and Eaton fires. The National Weather Service says most of the region is likely to get less than an inch of precipitation. But there is a threat of localized cloudbursts causing mud and debris to flow down hills. Rain is expected to increase throughout Sunday and could last into Tuesday. Flood watches have been issued for some burn areas.