Derecho and tornado outbreak of April 4–5, 2011
On April 3, supercells formed in Illinois, and a squall line of severe thunderstorms formed in Iowa. The severe thunderstorms made large hail, and strong wind, and potentially tornadoes. Then, heavy rain formed west of the severe thunderstorms but the line kept producing severe weather. On April 4, the supercells also turned into a squall line of severe thunderstorms. The storms produced tornadoes.  Then, supercells formed in Tennessee and produced tornadoes. By the night of April 4, the 2 lines of storms collided and moved East. By April 5, the severe thunderstorms were in New Jersey, Maryland, Delaware, Virginia, North Carolina, and Florida and moved out to sea. The storm produced a lot of tornadoes. Plenty of severe thunderstorm and tornado watches and warnings were issued.