Late winter storm delivers steady overnight rain in LA County

Widespread flood watches and evacuation warnings in recent wildfire burn areas are in effect Thursday as the peak of a winter storm delivered heavy rain, snow and a possible tornado in Southern California.

The rainfall arrives about two months after January wildfires in Southern California, including the Palisades and Eaton fires in Los Angeles County. The fires stripped brush from hillsides, leaving them more vulnerable to mud and debris flows as rainfall rates increase.

Rainfall rates will mostly be light to moderate, but periods of heavy rain are possible through the overnight hours into Thursday morning. Expect showers into the afternoon and significant snow in the mountains.

"We're dealing with a fast moving storm that's going to dump down a lot of rain in a short amount of time," said NBCLA meteorologist Melissa Magee.

Evacuation warnings went into effect Wednesday morning for some wildfire burn scars in Los Angeles and Orange counties. Many areas were under flood watches, indicating the potential for flash flooding.

More than 10,000 feet of concrete barriers and more than 6,500 sandbags were in place in the Palisades Fire area, according to the city. A line of the K-rail barriers were positioned on Pacific Coast Highway, which had been open to people who live and work in the Palisades area, but was closed Wednesday due to the storm.

The Santa Monica-Malibu Unified School District announced that all Malibu schools will be closed Thursday due to road closures.

In Sierra Madre, an evacuation warning and orders were in effect due to the possibility of debris flows in the Eaton Fire area. During the mid-February storms, a debris and rock flow in little Santa Anita Creek damaged homes and streets.

Evacuation warnings also went into effect for canyons near the Airport Fire in Orange County.

In the mountains, snow levels could be low enough to impact travel through major mountain passes.

In Pico Rivera, the National Weather Service was investigating reports of a weak tornado.

The rainfall comes after a slow start the wet season in Southern California. Extreme drought has spread into parts of San Bernardino, Riverside, Los Angeles, Orange and Ventura counties. Most of Los Angeles County is under moderate drought, the least severe drought category, in the lastest US Drought Monitor report.

At this time last year, California was drought-free after significant rainfall in February, according to the report.

See below for what to expect and when for the remainder of this week.

When will it rain?

A cold front arrived overnight, bringing some of the highest rainfall rates of this second storm of the week.

The most intense periods of rain are expected early Thursday morning. The heavy rain could cause flooding and raises the risk of debris flows in burn scar areas.

Here's a timeline of what to expect.

• Wednesday night into Thursday morning: A line of heavy rain will move from west to east across the region with periods of more intense rainfall. Rainfall rates of 1/2 to 3/4 inch are possible, raising the risk of flooding and debris flows.
• Thursday afternoon: Scattered showers with a chance of thunderstorms.
• Friday: More showers with significant snowfall in the mountains.

Rain totals for Wednesday into Thursday will range from 1 to 2 inches for most areas with 2 to 3 inches possible in the foothills and mountains.

A winter storm warning is in effect for area mountains into Saturday morning. Some areas will see 1 to 2 feet of snow with up to 5 feet possible elsewhere.