A strong storm moving across Southern California is bringing a significant amount of rain Tuesday, triggering a flash flood watch for much of the region.

Widespread rain and even the possibility of tornadoes are expected overnight and into Tuesday from the first significant storm of the season, triggering flash flood watches and advisories for several areas and raising the risk of debris flows in wildfire burn zones.

Residents in the areas burned this year in the Palisades Fire, the Eaton Fire and the Sunset Fire in the Hollywood Hills are advised to prepare for mudslides.

In Orange County, authorities issued an evacuation warning for areas near the Airport fire burn scar, including for the Trabuco Creek area and Modjeska Canyon.

According to the National Weather Service, the Wolf Creek weather station has recorded 1.8 inches of rain since Monday morning, adding to the more than 4 inches that fell over the weekend. With already saturated ground, even moderate rainfall could quickly lead to dangerous conditions.

"We saw rainfall upwards of half an inch in 10 to 15 minutes," a National Weather Service meteorologist told The Arizona Republic.

October nor’easter will continue to intensify as it tracks up the East Coast, bringing with it the potential for heavy rain and powerful winds.

The San Juan River has overflowed in some areas in southwestern Colorado, prompting evacuations in Pagosa Springs.