Tornadoes in October, November: Fall Considered Second Severe Season

Spring is known for its strong storm systems that can create violent twisters. However, it's not the only season known for tornadoes. Autumn is considered the "second" tornado season.

"The second half of October and especially November can often be a second season for tornadoes and severe thunderstorms," said tornado expert Dr. Greg Forbes. "In many ways, this is the counterpart to spring, when strong fronts and upper-air systems march across the United States. When enough warm, moist air accompanies these weather systems, the unstable conditions yield severe thunderstorms and sometimes tornadoes."

While most of the largest tornado outbreaks still occur in spring, autumn has its share of storms as well. Dr. Forbes examined the storm statistics and found six of the largest 55 known tornado outbreaks occurred in October and November.



http://www.weather.com/news/tornado-central/fall-second-tornado-season-20131002