Southern Californians braced for more wet weather this week, with light rainfall pushing through the region Tuesday ahead of a stronger, colder storm expected to arrive late today, bringing with it the possibility of snow, strong winds, thunder and dangerous mud and debris flows in areas recently scarred by major wildfires.

The National Weather Service said Tuesday afternoon that flood watches and evacuation warnings have been issued, as authorities prepare for potential flooding and debris flows when the rain intensifies.

The initial storm was expected to continue through Tuesday evening, bringing no more than a quarter-inch of rain to the region, the weather service reported. But the light rain is just a precursor to a second storm, projected to bring heavier rain tonight into the predawn hours Thursday as a cold front passes over the region, the weather service has said.

Areas along the coast and in the valleys could see 1 to 2 inches of rain, while the mountains and foothills could see 2 to 4 inches, the weather service said.

Between tonight and Thursday morning, there will be a “pretty intense rainfall pointed right at Los Angeles County,” weather service meteorologist Rose Schoenfeld said, which could bring a majority of the expected 1 to 2 inches.

A downpour in a short period could be problematic for fire-ravaged Los Angeles County.

Shallow debris flows and minor flooding are likely in burn scar areas, with a flood watch for most of Los Angeles County and a 30% to 50% chance of significant flooding and debris flows within that area, the weather service said.

L.A. County Public Works crews prepared debris basins, stabilized slopes and reinforced drainage systems to reduce flood risk, particularly in the areas affected by the Palisades, Eaton and Franklin fires and other recent blazes, the agency said.

“While these efforts reduce flood risk, the storm could still bring moderate debris and mudflows to burn areas, potentially blocking streets and threatening structures depending on their location and the local terrain,” the agency said in a statement.

Empty sandbags are available at all fire stations across the county, but sand is only available at certain locations. Residents can check the L.A. County Public Works website to find their nearest station.

L.A. County’s Mudflow Advice Hotline can be reached at 800-933-0930 for questions about debris flows. For storm preparedness tips, the county advised residents to visit ready.lacounty.gov.

The Los Angeles Fire Department issued evacuation warnings for areas near the Palisades, Sunset and Hurst fires, set to begin this morning and last until Thursday evening.

“Homes in the warning area with high risk will be visited by LAPD,” the department announced on its website. “If you are not home, they will leave a flyer with important evacuation information.”

Additionally, Caltrans was expected to close a segment of Pacific Coast Highway to residents and businesses in burn scar areas at noon today due to safety concerns from the incoming storm. Only emergency vehicles and U.S. Army Corps of Engineers debris-hauling contractors will be allowed through the closure. Residents with homes in the burn scar area should consider alternate routes in the afternoon or choose teleworking if possible, officials said.

Evacuation warnings had not been issued for areas near the Eaton fire.

The storm could bring 2 feet of snow at or above 6,000 feet in elevation in the mountains, with lighter accumulations down to 3,000 feet, which could impact mountain passes like the Grapevine, forecasters said.

A flood watch will remain in effect until Thursday evening across Orange, Riverside, San Bernardino and Los Angeles counties.

The Orange County Fire Authority is preparing for potential debris flows and mudslides Thursday, particularly near the Airport fire burn scar, according to fire Capt. Greg Barta.

“Should a debris flow issue arise, we have a plan in place with the sheriff’s department and Orange County Public Works to enter unified command, bring in additional resources and assist with rescues if necessary,” he said.

Orange County is expected to receive 1 to 2 inches of rain at lower elevations and 2 to 4 inches in the foothills and mountains, weather service meteorologist Sebastian Westerink said. The highest peaks of the Santa Ana Mountains may even see a light dusting of snow.

Sandbags and sand are available at fire stations across the county, and locations can be found on the Fire Authority’s website.

The Airport fire burn scar could see up to three quarters of an inch of rain per hour, weather service meteorologist Paul Steward said. That rate is above the predetermined threshold — the amount of water a burn scar can handle before a mudslide or debris flow occurs, according to O.C. Public Works spokesman Shannon Widor. Evacuation warnings in Trabuco Canyon will likely be announced this morning, Widor said, as well as a potential road closure depending on rainfall amounts.

While the second storm is not expected to develop into an atmospheric river, it will bring significantly more rainfall than the first, Westerink said.

The Inland Empire will likely see slightly less rain than neighboring counties, weather service meteorologist David Munyan said. The expected precipitation was between 1 and 1 1/4 inch at lower levels, and slightly more near the mountains.

However, there is still enough of a risk of debris flows and flooding. The Airport burn scar, which stretched into Riverside County, has a critical threshold of half an inch of rain in one hour, Munyan explained. In San Bernardino County, the Line fire’s threshold is only slightly higher, at 0.6 inches.

Riverside County Fire Department and San Bernardino County Fire Department stations will be at full staffing ahead of the expected rainfall. All stations will have empty sandbags available. San Bernardino County residents can refer to the fire department’s website to find the nearest station to pick up sand, while Riverside County Fire Department spokesman Capt. John Clingingsmith advised residents to call their nearest station to find out where sand can be picked up.

“We ask residents to pay close attention to news and social media,” San Bernardino County Fire Department spokesman Eric Sherwin said. “Be prepared to go at a moment’s notice. ”

City News Service contributed to this report.