Southern California is experiencing its fourth significant storm in a week, prompting widespread weather warnings across major centers.
The downpour brings risks of flash flooding, debris flows -- especially in regions scarred by recent wildfires -- and significant disruption to transportation and daily life.
Flooding is one of the deadliest weather hazards in the United States, according to the National Weather Service (NWS), with swift water flows capable of endangering travelers and residents in at-risk areas.
As of early Friday morning, the NWS had issued a flood watch, which means "conditions are favorable for flooding," from 10 p.m. Thursday through Friday morning for much of Los Angeles County, per the LA Times.
A flash flood warning, which means a flash flood is imminent or occurring and residents should move to higher ground, was also due to be active in parts of Riverside and Imperial counties through Friday evening. And another flash flood warning was in force for Mission Viejo, Lake Forest, and Aliso Viejo until 5:30 am PST at the time of writing.
Thunderstorms are expected to continue into Friday morning, with the NWS forecasting rainfall rates as high as 1 inch per hour in some locations. By Saturday morning, showers may still linger in Los Angeles County, but conditions are expected to improve throughout the weekend, with dry and cool weather anticipated for the start of Thanksgiving week.
The NWS says: "A flash flood warning is issued when a flash flood is imminent or occurring. A flash flood is a sudden violent flood that can take from minutes to hours to develop. It is even possible to experience a flash flood in areas not immediately receiving rain."
Dave Munyan, a meteorologist with the National Weather Service office in San Diego, told the LA Times: "We could actually see winds turn out of the south, and maybe out of the east...we could see precipitation moving northward and even westward back from the deserts into some of the mountain areas come Friday afternoon into Saturday."
Delivery driver Cindy Portill told ABC7: "I'm trying not to get into any accidents because a lot of people drive crazy."
Flood and flash flood warnings are expected to remain active in impacted counties at least through early to mid-day Friday, with some advisories extending into Friday evening or Saturday for southeastern areas.
Showers may persist into Saturday morning, especially in Los Angeles County, but are forecast to taper off as the weekend progresses.
The NWS is advising all residents to avoid driving during peak rainfall and never attempt to cross flooded roads. Authorities urge those in flood-prone or wildfire-scarred areas to remain vigilant, monitor official alerts, and follow evacuation orders if issued.
The remainder of the Thanksgiving week is expected to bring drier, cooler weather with temperatures rising into the mid-60s and low 70s for much of the region.