The first major storm of the season brought widespread rain to the drought-stricken Southland Monday, bringing showers, gusty winds and a chance of mudslides.

Moderate to heavy rain began falling in Los Angeles County after noon, prompting the National Weather Service to issue a flood advisory. Forecasters warned of likely roadway flooding, as well as the risk of minor mud and debris flows in fire-scarred areas over the next several hours.

The storm is being fueled by an atmospheric river – a long plume of Pacific moisture – that has already brought record-breaking rainfall to Northern California.

San Francisco received 5.5 inches of rain over a 24-hour period, breaking an all-time high.

“It’s been a memorable past 24 hours for the Bay Area as the long talked-about atmospheric river rolled through the region,” the local weather office said. “We literally have gone from fire-drought conditions to flooding in one storm cycle.”

The vicious weather system is moving toward Southern California Monday, where .5 to 1.5 inches of rain are forecast for Los Angeles and Ventura counties, according to the NWS.

The heaviest showers arrived in Los Angeles County around noon.

“Stay away from any moving water, whether you’re on foot or in your vehicle,” Los Angeles County Fire Department Capt. Ron Haralson said.

Moderate to heavy rain, roadway flooding, and debris flows were reported in recent burn areas.

Officials warned residents in the Bobcat Fire scar area should be on high alert as the storm passes through Monday. The Bobcat Fire scorched about 116,000 acres last September.

Sandbags for members of any community concerned about flooding were available at Los Angeles County Fire Department stations around the region. Proof of residency may be required.

An interactive map to locate the nearest fire station with sandbags can be found on lacounty.gov.

Further north, officials are concerned about possible flooding in the recent Alisal Fire burn area.

Evacuation orders have been issued for residents west of Las Flores Canyon, east of Mariposa Reina, south of West Camino Cielo, and down to the ocean.

More information can be found at readysbc.org.

A flash flood watch was in place for the Santa Barbara County mountains and South Coast Monday morning, according to the Weather Service.

A flash flood warning was in effect through 7:15 p.m. for the El Dorado Fire burn scar area in San Bernardino County. Several residents in the area sheltered in place due to the debris and mud flows, the San Bernardino County Fire Department said on Twitter.

More than 120 public safety responders were out Monday night clearing roadways and flood channels.

Evacuations orders for Potato Canyon Road, El Dorado and Apple burn scar areas were in effect through 8 p.m.

State Route 38 was closed between Lake Williams and Valley of the Falls due to mud and debris flow, officials said, and was not expected to reopen until Tuesday.

Drivers are urged to take the following steps to prepare for the storm:

• Check your windshield wipers and replace if cracked or worn
• Slow down on wet roads and leave extra room for stopping in traffic
• Watch for rocks and debris on canyon roads
• Don’t drive across flooded roadways (Turn Around Don’t Drown!)

Monday’s storm is much needed after California experienced its second driest year on record in 2021. Some of the state’s most important reservoirs are at record low levels.

Wind advisories will be in place Monday for parts of Los Angeles, Ventura, Santa Barbara, Riverside and San Bernardino counties.

The advisories extend into early Tuesday morning for Riverside and San Bernardino counties.

Dry and sunny skies are expected to return Tuesday afternoon. A high near 90 degrees is expected for downtown Los Angeles by Thursday.