ATLANTA (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 after 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.

Southern California could get drenched

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.

Tornadoes take aim at the South

As the system moves east, a regional outbreak of severe thunderstorms is expected over large parts of several southern states beginning Friday and continuing into Saturday, according to the latest forecasts from the federal Storm Prediction Center.

That means a variety of severe weather hazards, from thunderstorms to so-called supercells that can spawn destructive tornadoes.

The worst weather could strike parts of Missouri, Arkansas, Mississippi and Tennessee on Friday, then move into Alabama by Saturday, though it was too early to say which areas could be hardest hit.

High winds expected to increase wildfire threat

The threat of wildfires in parts of the Southwest is already high, with forecasts of critical wildfire conditions on Tuesday in the southeastern corner of Arizona and in southern New Mexico. Parts of west Texas also are at risk.

Strong winds that will likely accompany the incoming storm system are likely to add more concerns about wildfires later in the week, especially in the southern Plains, according to the National Weather Service.

Residents south of Dallas clean up after earlier storms

In Texas, residents were cleaning up storm damage over the weekend.

Strong winds of up to 90 mph (145 kph) ripped the roof off a Days Inn along Interstate 45, and the high winds also damaged homes throughout Ellis County.

The 42-year-old man who died in the RV was identified as T.J. Bailey from Midlothian, Texas. His wife and two sons were inside the RV when it rolled over at the racetrack, Ellis County Justice of the Peace Chris Macon told The Dallas Morning News. Bailey’s family members were treated at a hospital for non-life-threatening injuries.