1 of 2 A powerful tornado hit the US state of Mississippi — Photo: GETTY IMAGES A powerful tornado hit the US state of Mississippi — Photo: GETTY IMAGES
“I had never seen anything so violent or heard that sound that sounds like a train horn coming your way.”
With these words Stephanie Cox, a storm chaser, described the devastating tornado that slammed through the state of Mississippi in the United States last week, causing 26 deaths and extensive damage.
“I still can’t get over what I saw,” Cox told the BBC of the weather phenomenon, which she called “monstrous”.
And the storm chaser has probably seen a lot. She lives in Oklahoma, a state whose capital, Oklahoma City, is known as the most tornadohit city in the country.
According to estimates by the US National Oceanic and Atmospheric Administration’s Storm Prediction Center (SPCNOAA), there were already more than 170 of them.
2 of 2 USA records about 1,200 tornadoes per year — Photo: GETTY IMAGES USA records about 1,200 tornadoes per year — Photo: GETTY IMAGES
The Tornado FAQ section of the SPCNOAA website states that “the United States remains the number one location for tornadoes,” although it is difficult to measure the number of tornadoes that occur worldwide. This happens for a number of reasons, including methodological differences.
An average of about 1,200 tornadoes are recorded in the United States each year.
Other places where these phenomena are common are the Canadian provinces of Alberta, Manitoba and Saskatchewan, northeastern Mexico, Bangladesh, the United Kingdom, northern Argentina, southern Brazil and southwestern Russia.
But what makes the US so vulnerable to tornadoes?
Location and combination of factors
Scientists say the causes that lead to the formation of tornadoes are not yet fully understood. But they are known to tend to occur when cold, dry air meets warm, humid air.
And that happens most often in midlatitudes, right where the US is located.
Add to that the cold air that flows freely from the north across the Great Plains, the proximity to the warm waters of the Gulf of Mexico, and the dry air that rushes in from the Rocky Mountains.
In the US, it is customary to speak of a “tornado corridor” in these areas.
Experts point out that it’s no coincidence that the regions of Mexico and Canada, where the most tornadoes occur, border the United States.
However, experts point out that recent trends suggest there is a second risk zone stretching from the southeast of the country north through the midAtlantic region.
SPCNOAA warns that the “tornado corridor” is only a map of locations where these types of phenomena have been more prevalent.
“Outside of this tornado corridor, violent or deadly tornadoes occur every year. Tornadoes can occur almost anywhere in the United States, including west of the Rocky Mountains and east of the Appalachian Mountains, and even in Canada and abroad,” the website reads.