Dallas Tornado a Reminder the Fall Second Severe Weather Season Is Here

October 21, 2019
The 1991-2010 average number of October tornadoes in the U.S. is 61.

Spring draws much of the attention when it comes to damaging tornadoes, but as Sunday night's destructive tornadoes and storms in the South show, fall is also notorious for an uptick in tornado activity.

The Dallas metro area suffered major tornado damage Sunday night, and parts of Arkansas, Louisiana, Missouri, Oklahoma and Tennessee saw damaging severe storms as well.

Although it may seem unusual, October is the 3rd most tornadic month of the year in Dallas County. Not including Sunday night, there are 11 confirmed tornadoes in Dallas County during the month of October (1880-2018), according to the National Weather Service. Only April (23) and May (24) have had more tornadoes there.

The atmosphere can become unstable in the fall as cold fronts and jet stream winds become stronger and interact with warm, moist air. That allows severe thunderstorms with damaging winds, large hail, and sometimes tornadoes, to develop.

Most of the time, the second-season tornado outbreaks happen in the South where warm and moist air is more common, but they can sometimes spread farther north.

(MORE: Your Average Tornado Risk by Month

Last year provided a strong reminder of the threat posed by tornadoes in fall.

Two of the top three most active days for tornado reports in 2018 - Halloween and an Illinois Dec. 1 outbreak - were in the fall, rather than the typically more volatile spring or early summer months.

The 1991-2010 average number of November tornadoes in the U.S. is 58.

Many of the tornadoes in the 2018 Halloween outbreak occurred after dark, which is another characteristic of second-season tornadoes.

Given the fewer hours of daylight in standard, rather than daylight time, any cold-season southern tornadoes have a greater chance of occurring after sunset.

As you can see in the graph below, there is a pronounced nighttime tornado maximum during fall in the month of November.

U.S. nocturnal (defined as from 9 p.m. to 6 a.m. CST) tornadoes (F/EF1 or stronger) by month from 1953-2015.
(NOAA/SPC via the National Weather Association)

Even the core winter months of December through February have averaged 3 to 6 nocturnal tornadoes in the U.S. each month, according to NOAA's Storm Prediction Center.

These colder month tornadoes often occur with a very strong jet stream, meaning winds aloft can move the parent supercells or squall lines in which these tornadoes are embedded at speeds of 60 mph or more, giving little time to seek shelter.

Biggest Second-Season Tornado Outbreak: Nov. 21-23, 1992 – 105 Tornadoes

The biggest second-season tornado outbreak started the Saturday before Thanksgiving 1992 in Houston.

Tornadoes hit parts of 13 states, from Texas to the Carolinas, killing 26 people and injuring 638.

White Plains, Georgia, was practically leveled by an F4 tornado on Nov. 22, 1992.
(John Bazemore/AP)

An incredible seven tornadoes spawned in the span of just two hours in the Houston metro area, with three twisters on the ground at the same time in Harris County. The strongest tornado, rated F4, destroyed more than 200 homes on Houston's east side. This was the strongest tornado to hit the Houston metro since 1950.

Another F4 tornado went on a 128-mile rampage through Mississippi overnight Saturday into Sunday morning, Nov. 22. The storm claimed 12 lives and damaged or destroyed more than 700 homes.

Fifteen tornadoes touched down in Indiana that Sunday – the largest November outbreak in state records. One tornado was an F4 in southeastern Indiana and northern Kentucky. Other F4 tornadoes carved a swath through the far northwestern suburbs of Atlanta and also struck near White Plains and Lake Oconee, Georgia.

Finally, a pair of F3 tornadoes in North Carolina killed two and injured 59.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.


The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.