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El Ni帽o and a polar vortex behind deadly US tornadoes

Extreme weather in the southern and Midwestern US has killed at least 43 people. El Ni帽o and a strong polar vortex are being blamed
Tornadoes rip through US
Tornadoes rip through US
Laura Buckman/AFP/Getty

Weird, deadly weather is pounding the US. A cluster of tornadoes have swept through northern Texas and the Midwest in the past week, bringing snow, floods and heavy winds. At least 43 people have died.

While such large tornado activity is unseasonal, it isn鈥檛 without precedent. In the past, El Ni帽o years have spawned large storm systems late in the year聽鈥 in 1957 and 1982, for example. And this year鈥檚 El Ni帽o is the strongest ever recorded.

A strong polar vortex probably compounded the situation, keeping the cold air from the east out, says Marshall Shepherd, a meteorologist at the University of Georgia in Athens. 鈥淭he unusually warm December primes the atmosphere for a significant contrast, and thus the battleground that we鈥檝e seen play out,鈥 he says.

Topics: Climate change / floods / United States / weather