At least three people have died in severe weather in the southern states of the United States, where tornadoes, damaging hail and flash floods left a swath of destruction.

Tornadoes churned across many states, from Louisiana to Georgia, but the most destructive were in Louisiana and Mississippi.

More than 30 people were injured in the storms. Two people died in the hamlet of Convent, Louisiana,
after a tornado demolished more than 160 mobile homes.

The third casualty died in a trailer park in Purvis, Mississippi.

The storm left tens of thousands of people without power in Louisiana, and John Bel Edwards, the state governor, declared a state of emergency in seven parishes.

The powerful storm developed when the jet stream dived across the region on Tuesday. A jet stream is a fast-flowing ribbon of air, blowing high above the Earth's surface, which can dictate the path of storms and can also encourage their development.

Tuesday's jet stream was particularly intense and it is unusual for one this strong to travel so far south. This resulted in a particularly powerful storm, and encouraged moisture to be fed into the system from the Gulf of Mexico.

As the system developed, the winds above the Earth's surface were much stronger than at ground level. This encourages the air to start to roll, and it is this rotation that encourages the formation of tornadoes.

The storm system is now heading northeast across the eastern portion of North America. As it does so, its weather will become increasingly wintry. Up to 30cm of snow is expected in the northeastern US and eastern Canada on Wednesday.

Further south, torrential rain and damaging hail will be a hazard, and there is a threat of more tornadoes. Virginia and North Carolina will be most at risk.

Source: Al Jazeera and agencies