Storm slams Southern California as Central U.S. faces winds, fire threat

Several U.S. states were under threat from more extreme weather overnight, as heavy rains in Southern California caused flooding and mudslides — triggering mandatory evacuation orders and sparking rescue operations Tuesday.

Threat level: A "rapidly strengthening storm system" was set to generate high winds from the Southwest to the Upper Midwest, with gusts "up to and in excess of 75 mph in some areas," per the National Weather Service. The Southern and Central Plains face "abnormally high temperatures" and the threat of wildfires, the NWS said.

What's happening: Heavy rains from a moderately strong atmospheric river event saw several rescue operations launched along the swollen Los Angeles River on Tuesday, after several Orange County residents became trapped by mudslides, per the Los Angeles Times.

• Evacuation orders were issued for several communities in O.C., as mudslides and flooding threatened areas scarred by wildfires, the Orange County Register reports.
• While evacuation orders were lifted late Tuesday, firefighters continued to patrol the area overnight, the Orange County Fire Authority said.

What to watch: High wind watches and warnings were in place from the Desert Southwest to the Upper Midwest, where widespread power outages were expected.

• Days after the deadly tornadoes that pummeled the Central and Southern U.S., the NWS warned there could be more twisters in the new storm system, with a slight risk of severe thunderstorms over parts of southern Minnesota and northern Iowa, effective Wednesday through Thursday.
• Winter storm watches, warnings and advisories were in effect from the West Coast through the Rockies, with widespread heavy snowfall forecast to persist over the western U.S. through Thursday.

By the numbers: More than a foot of snow was set to accumulate in the mountain ranges of the Central Great Basin and Northern and Central Rockies overnight.

• Another round of heavy snow was set to hit the Sierra Nevada and neighboring Cascades Wednesday afternoon, with snowfall accumulations of 8-12 inches expected.

Meanwhile, "record breaking heat" was likely to impact the Central and Eastern U.S. through Thursday, the NWS said.

• Unseasonably warm weather, strong winds, extremely dry fuels and low relative humidity levels were set to strike the Central and Southern Plains over the next few days, "producing highly favorable conditions for the spread of wildfires," according to the weather service.
• The NWS said much of the Texas and Oklahoma Panhandles faced a "Critical Risk of Fire Weather" through Wednesday morning.

Context: Climate change is altering the environment and increasing the odds of extreme weather events, per Axios' Andrew Freedman.