ATLANTA, March 11, (AP): A potent storm system is expected to pour heavy rain on western states later this week before rumbling into the central United States, where it could spawn tornadoes in the South and dump heavy snow across the parts of the Great Plains and Upper Midwest, creating blizzard conditions.

The ominous forecast comes as temperatures hit record highs in parts of the central US after an active few days of weather across the nation. A possible tornado touched down in central Florida on Monday morning, tearing past a local television news station as its meteorologists were live on the air. No injuries were reported.

In Texas, thunderstorms on Saturday toppled semitrailers on Interstate 35 in Texas and flipped over a recreation vehicle at the Texas Motorplex drag racing strip south of Dallas, killing a man inside the RV. Much of the Midwest got hit by heavy snow and blizzard conditions last week, but the region began this week with springtime temperatures.

Readings reached the 60s in many parts of Minnesota on Monday and hit 76 in the western town of Granite Falls by mid-afternoon. Omaha and Lincoln, Nebraska both set records Monday with temperatures in the low 80s (20s Celsius). Readings in the 60s and low 70s (teens to 20s Celius) were also common across South Dakota.

But dry conditions and high winds raised the wildfire risk over much of the Midwest, with red flag warnings out for most of Nebraska and South Dakota, and parts of Kansas, Missouri, Iowa and Minnesota. The system moving in later this week is expected to begin with an atmospheric river soaking Southern California with heavy rain on Thursday, the National Weather Service projects.

Atmospheric rivers are plumes of water vapor that form over the ocean and can drop tremendous amounts of moisture over land. "Snow and wind will spread across the Intermountain West and Rockies Thursday into Friday before rapid development occurs over the Plains,” according to the federal Weather Prediction Center in College Park, Maryland.