A neighbourhood lies destroyed after a tornado tore through Harrisburg, Illinois on 29th February 2012  [AFP]

Tornadoes have killed at least 13 people after massive storms ripped through the US Midwest on Wednesday. Homes were smashed, cars were tossed into lakes and trees were uprooted as the powerful systems whipped up violent winds, hail and funnel clouds.

The swathe of destruction extended from Kansas, Missouri, Illinois, Indiana, Nebraska into Kentucky. Harrisburg, Illinois was hardest hit after a deadly twister stayed on the ground there for several kilometres and was estimated to be up to 100m wide. At least 10 people were killed and more than 100 injured in this town of around 10,000.

The tornado had a preliminary rating of EF4, the second most powerful on the rating scale, according to the National Weather Service. Less than 1% of all tornadoes reach this intensity.

There were over 30 reports of tornadoes across the six affected states since the storms began late on Tuesday. There were also severe thunderstorms across the south as the tail end of the same storm system moved through Alabama, Georgia, Mississippi, North Carolina and Tennessee. The worst of the weather is now clearing away from the Eastern Seaboard.

These storms were slightly earlier than usual but by no means unprecedented and they often miss highly populated areas altogether. If the Harrisburg tornado had passed 100 km or so to the north or to south it would have simply left a scar across broad open Plains. This twister was the deadliest to hit Illinois since an April 2004 tornado killed eight people in Utica.

The early start to this year’s tornado season does suggest that this could be another very active year. In 2011, tornadoes killed 550 people in the United States. It was the deadliest tornado season since 1936 and the third worst on record.