The tornado outbreak of May 18–21, 2013 was a significant tornado outbreak that affected parts of the Midwestern United States and lower Great Plains. This event occurred just days after a deadly outbreak struck Texas and surrounding southern states on May 15. On May 16, a slow moving trough crossed the Rockies and traversed the western Great Plains. Initially, activity was limited to scattered severe storms; however, by May 18, the threat for organized severe thunderstorms and tornadoes greatly increased. A few tornadoes touched down that day in Kansas and Nebraska, including an EF4 near Rozel, Kansas. Maintaining its slow eastward movement, the system produced another round of severe weather nearby. Activity significantly increased on May 19, with tornadoes confirmed in Oklahoma, Kansas,