Tornadoes in the United States
The Midwestern states are very prone to tornado activity, as they are part of "Tornado Alley." States included in the area that are hit by tornadoes the most are Oklahoma, Kansas, Missouri, Nebraska, Iowa, and South Dakota. The Midwestern States are often hit by tornadoes during the late spring and early summer months, especially the months of May and June. This is due to the aforementioned air mass moving northward into the Midwest and combining with another air mass that move southward from Canada. This creates unstable air, creating the potential for storms to strike the most during these months. The frequency begins to decrease in the middle of the summer, as the air mass moves northward into the Great Lakes states.
Climate of Houston
Unlike Dallas, Houston is not in Tornado Alley; however, smaller tornadoes can occur during severe weather. They are most likely to be found along frontal boundaries of an air mass during the spring months. Tornadoes in Houston usually measure a weak F1 on the older Fujita scale and cause light to moderate damage to well-constructed buildings. The strongest recorded tornado in Houston history was an F4 on November 21, 1992, part of a large outbreak of tornadoes in Harris County.