A tornado in December? A rarity due to climate change

The more than 30 tornadoes that struck last Friday night in six states of the U.S, leaving dozens of deaths, are an exception that experts attribute to climate change.

According to data from the National Office for Oceanic and Atmospheric Administration (NOAA), the mean number of tornadoes that made landfall in Kentucky in a December between 1991 and 2010 it was zero.

And in Tennessee is the same number, while in Illinois it is one and in Arkansas it is two and in the whole country it is only around a dozen.

These four states are the ones that concentrate, so far, the list of fatalities by the tornadoes on Friday, with four confirmed deaths in Tennessee, six in Illinois, one in Arkansas and the more than 70 that may be feared in Kentucky.

And what made Friday night so unique was, in addition to the number and latitude, the force with which the tornadoes made landfall in Missouri Y Mississippi.

So much so that it is estimated that the tornado that affected four states on Friday and ravaged the town of Mayfield (Kentucky), where 70 people are feared under the rubble of a candle factory, traveled hundreds of kilometers.

The governor of Kentucky, Andy Beshear, assured that the tornado made landfall and stayed that way for 227 miles (365 kilometers), which would make it the longest distance traveled since there are records in the United States.

And if Beshear’s fears are confirmed, that the final figure will exceed 100 deaths, Friday’s would also be one of the deadliest in the country and by far the one that caused the most fatalities in Kentucky.

WHAT IS A TORNADO?

Tornadoes form when cold air collides with warm, humid air and pushes it downward, and as the hot air rises, it creates a rotating, updraft, according to the National Center for Atmospheric Research.

And there is the key, that there is warm and humid air at this time of the year in states where temperatures close to zero degrees Celsius are normally recorded.

For this reason, tornado numbers are low in the winter months and those that exist tend to be concentrated in the states closest to the Gulf of Mexico, with a milder climate in December, but not in the interior of the country and as far north.

“It was one of the most shocking weather events in my 40 years as a meteorologist – a violent tornado (in December!),” Meteorologist Jeff Masters tweeted.

John Gordon, a meteorologist with the National Weather Service Forecast Office in Louisville (Kentucky), described what happened in the state as a “perfect storm” that combined the cold season with warm air.

“The worst case scenario happened. Warm air in the cold season, in the middle of the night, ”Gordon said of the collision between the cold air mass of an anticyclone moving east with a hot air mass that had raised temperatures on Friday at 26 degrees in the neighbor Memphis (Tennessee), for hours later to be only 1 degree above zero.

In this sense, the meteorologist Craig Ceecee was very clear in a tweet in which he said that the reason for a tornado “so massive” in December is because the “atmosphere did not know it was December.” EFE

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