The National Weather Service (NWS) has issued a tornado warning for several states in the US.
Large sections of Indiana, Illinois, Missouri, Oklahoma, and Texas.
Strong winds and hail greater than two inches in diameter.
Roughly eight million people live within areas with an enhanced risk of severe weather.
Tulsa, Okla., St. Louis, Springfield, Mo., and Evansville, Ill., are among the areas facing an enhanced risk.
The storm system is expected to strengthen as it continues east, bringing heavy rainfall and the threat of flash flooding to the Upper Ohio Valley.
Heavy showers, winds, and thunderstorms are expected to spread into the Appalachians and the Mid-Atlantic on Tuesday.
Rainfall totals may exceed two inches in many areas and up to five inches locally in others.
Two separate low-pressure centers over the Great Lakes and the Mid-Atlantic are expected to converge by midweek, culminating in an early April nor'easter.
The nor'easter could bring six inches or more of snow across the Great Lakes and the Northeast late in the week.
Southeast: Texas, Oklahoma, Arkansas, Louisiana, Mississippi, Alabama, Georgia, Florida
Midwest: Missouri, Illinois, Indiana, Kentucky, Ohio, Tennessee
Northeast: Virginia, Maryland, Delaware, Pennsylvania, New Jersey, New York
Monitor weather updates closely.
Be prepared to evacuate if necessary.
Have an emergency plan in place for your family.
Take measures to protect your property.
Exercise caution while traveling on the roads.