Tornado Outbreak | The Massive & Deadly Tornadoes in Groups
A large tornado outbreak occurs a few times a year and can cause billions of dollars in damage while killing hundreds of people. Learn more about them here…
Tornado outbreaks happen all the time, whether there are just tornadoes in the single digits, or there are over 100 of them. Large tornado outbreaks are quite rare, but even small ones can cause the strongest tornadoes. There is a lot to learn and know about this deadly weather phenomenon. In this short post, we will learn a lot about these tornado outbreaks, with some science behind them, a few examples, and other things like that.
This post is all about the weather occurrence, the tornado outbreak.
Widespread Tornado Outbreaks
What is a Tornado Outbreak?
A tornado outbreak is the occurrence of multiple tornadoes spawning from many supercells within one weather system. Tornado outbreaks vary in size, all the way up to the largest with 362 tornadoes over four days. These outbreaks can also widely vary in length, from a few hours to several days. They can happen anywhere but are usually in places like Tornado Alley, Dixie Alley, and the Midwest. Outbreaks occur year-round, and to learn more about fall tornado outbreaks, click here, and for winter ones, click here.
How Do They Form?
Now that we talked about what tornado outbreaks are, we are going to the setup for a lot of them. If you knew before or have seen my other post, “How Do Tornadoes Form? | How Tornadoes Form & Where“, you know an acronym for tornado formation. The acronym is SLIM, which stands for (Wind) Shear, Lift, Instability, and Moisture. For more on that, go see that post. So basically, a tornado outbreak setup is just all of those tornado ingredients spread over a wide area. In most cases, everything has to be at a good level for tornadoes, but there are some exceptions.
For example, the 1997 Jarrell tornado had very little wind shear, but the environment had A LOT of instability. Some areas had nearly 7,000 J/kg when just 1,000 can make severe storms! There are other smaller-scale things you look at for tornado prediction but we will not talk about that right now. *good page by the NWS for those tornadic ingredients like that if you are interested here*
Where do They Impact?
As mentioned earlier in the post, tornadoes can happen anywhere, but usually happen in a Tornado & Dixie Alley, and parts of the Midwest, depending on a few factors. One factor can be the ENSO regions in the Pacific. Those regions are what scientists look at to determine if we are in an El Nino, La Nina, or Neutral phase. If you look at the map above, it shows that from March-May during a mostly El Nino influence, most of the 48 states have fewer tornadoes than average. But during a mostly La Nina influence, parts of Tornado Alley & Dixie Alley have more than average. More factors go into this so if you want to look at some more factors like the Northern Pacific Oscillation & see a tornado prediction for 2024 made by Ryan Hall Y’all, go here.
