 Complete the following phrase:  Oklahoma City has a very active severe weather season from March through June, especially during April and May. Located in the center of a region colloquially known as Tornado Alley, Oklahoma City is prone to especially frequent and severe tornadoes, as well as very severe hailstorms and occasional derechoes. Tornadoes have occurred in every month of the year in Oklahoma City, and a secondary smaller peak also occurs during the early autumn, especially in mid-September to late-October. The Oklahoma City metropolitan area is one of the most tornado-prone major cities in the world, with about 150 tornadoes striking within the city limits since 1890. Since the time weather records have been kept, Oklahoma City has been struck by thirteen violent tornadoes, eleven FEF4s and two FEF5s. On May 3, 1999 parts of southern Oklahoma City and nearby suburbs suffered one of the most powerful tornadoes on record, an F5 on the Fujita scale, with wind speeds estimated by radar at . On May 20, 2013, far southwest Oklahoma City, along with Newcastle and Moore, was hit again by another EF5 