Tropical Storm Barry forms in Gulf of Mexico and threatens to hit US as a hurricane

Tropical storm Barry which is currently moving over the gulf of Mexico is likely to develop into a hurricane.

It is forecast to hit the US city of New Orleans, which has already seen thunderstorms and flash floods.

A state of emergency is in effect and residents in some low-lying areas have been asked to evacuate.

Officials have warned that the Mississippi river could come dangerously close to over topping banks shielding the city.

It could rise as high as 20ft (6m) above sea level, they say, potentially exceeding the 20-25ft levees which protect the river from overflowing.

On Wednesday, the New Orleans metro area was hit by as much as eight inches of rain over a three-hour period.