It’s isn’t your imagination: Midwestern and Northeastern parts of the US really are experiencing an unusual amount of tornado activity recently. In fact, according to a meteorologist from the National Weather Center, there were 500 eyewitness reports of tornadoes made in the 30 days between April 27 and May 27.
Meteorologist Patrick Marsh says there have only been four other periods in the National Weather Service’s history of recording tornado activity where reports like this have exceeded that number, and they occurred in 2003, 2004, 2008 and 2011.
Considering the National Weather Service has been recording tornado activity for decades, it’s worth noting all of those record reporting windows happened in the last 15 years or so.
All of these numbers beg the same question: Is there a reason we’re seeing so many tornadoes right now? And Is there some pattern behind the bigger picture of increased tornado activity?
Recent storms have reached record numbers
Here are some more staggering figures from this recent streak of tornado activity:
- May 28 was the 12th consecutive day with at least 8 or more tornado reports in the US, which makes it the longest stretch on record for at least 8 reports per day
- The last day there was no tornado reported in the US was May 15
- Since May 15, there have been more than 365 tornado reports
- On average, there are 276 tornado reports in the month of May. This May, there have been more than 460.
- On average, there are about 750 tornado reports at this point in the year. So far, in 2019, there have been more than 960.
It could be the result of a very specific combination of weather patterns
Recently, we’ve been stuck in a specific weather pattern than creates a perfect environment for tornadoes. Cold air in the Rockies has been running into unusually warm air in the south. When that’s combined with a strong jet stream in the Plains and Midwest, it creates the wind shear needed for twisters to take shape. This pattern hasn’t been pronounced for the last couple of years, but it is now, and it’s lasting for longer than it usually does.
El Niño events contribute to extreme weather, but not necessarily tornadoes
We’re in an El Niño year right now, but that’s probably not the reason we’re seeing so many tornadoes. El Niño is the climatological event characterized by warming, eastward-moving Pacific waters. It can have a huge impact on weather patterns in the US, usually creating wetter weather in the Gulf area and a strong southern jet stream, which can lead to more “dixie alley” southeast tornadoes. However, the El Niño event we’re in now is rather weak, and in general, El Niño years tend to lead to less tornadoes.
More tornado reports could be the result of better reporting
When talking about recent tornado events, and the trends over the past few years, one of the key words to remember is “reported” events. Radar technology has improved, and so have the unofficial networks through which storms are tracked and recorded. Basically, scientists and storm chasers alike are better at detecting tornadoes than ever before. National Weather Service radars have doppler capability that can sample the winds in the storm. Meteorologists can now see debris within the storm that is an indication that a tornado has formed and has picked up debris. On top of it all, social media has helped get the word out about observed tornadoes, as well as large groups of tornado chaser and spotters than line the plains during severe weather episodes.