Kentucky tornadoes: death toll from record twisters expected to exceed 100

The death toll from record tornadoes that roared across hundreds of miles this weekend is expected to exceed 100 in Kentucky alone, with dozens still unaccounted for as crews scramble to search wreckage.

One tornado that tore through four states over four hours of nighttime devastation is believed to be the longest distance for a tornado in US history, leaving destruction, death and a frantic search by survivors to find family and shelter, from Arkansas to Kentucky.

Beshear said the path of devastation was about 227 miles (365km) long, which, if confirmed, would surpass the 218-mile so-called Tri-State tornado in 1925, which killed at least 695 people and destroyed 15,000 homes across Missouri, Illinois and Indiana.

Temperatures were below freezing in the night in Mayfield, Kentucky, a small city largely leveled by winds estimated at up to 200mph. Survivors were struggling Sunday with lack of power and running water.

Tragedy struck that city of just 10,000 people hardest, after the massive twister flattened a candle factory where about 110 employees were working the night shift on Friday into Saturday and only around 40 have so far been accounted for.

Beshear said on Sunday that no one has been found alive in wreckage in the town since shortly after 3am on Saturday.

A vast storm front moved across the Mississippi basin and parts of the US south-east and midwest on Friday night, spawning more than 30 tornadoes.

Spring is the main season for tornadoes and this latest event was very unusual coming in December, when colder weather normally limits tornadoes, said Victor Gensini, an extreme weather researcher at Northern Illinois University.

He has asked the Environmental Protection Agency (EPA) to investigate whether climate change played a role in the unusual tornado occurrence.

Illinois was hit, too, and six people were killed in the collapse of an Amazon warehouse in Edwardsville, with another injured worker airlifted to a hospital, fire chief James Whiteford said.

In addition, so far four people have been reported killed in Tennessee, two in Arkansas and two in Missouri as well as the high toll in Kentucky.

Parsons-Perez was stuck for three hours in the rubble, and documented part of it in a livestream on Facebook in which her co-workers can be heard crying in fear.

The storm was so powerful that a photograph from a tornado-damaged home in Kentucky was found almost 130 miles away in Indiana.

The US uniquely experiences more than 1,200 tornadoes annually, more than four times the number in other countries around the world where they occur, combined, according to experts.

The warm waters of the Gulf of Mexico send very warm air north. As that rises and meets with higher-level, very cold mountain air, with the differing levels also moving at various speeds, they can create a wind vortex that spins and then tilts vertically, as this Insider article explains, leading to extraordinarily powerful tornadoes.