 The tornado outbreak was caused by a large low-pressure system across the central United States that intensified on February 28 over Kansas, and a cold front moved across the region, providing the lift needed to develop storms.Additionally, a surge of very moist air from the Gulf of Mexico and warm temperatures across the south side of the storm expanded these developments.Temperatures were in the 70s °F (low 20s °C) in some areas to the south, while the mercury was below freezing on the north side.