AUSTIN (Texas) - Tropical Depression Bill drenched large parts of Texas, turning streets into lakes, raising flood worries and killing at least one person in the state where severe weather killed about 30 people last month.

Bill, the second named tropical storm of the 2015 Atlantic hurricane season, was forecast to bring 5cm to 10cm of rain in an area stretching from Texas towards Indiana, with a few places seeing as much as 30cm of rain, the National Weather Service said.

It was downgraded from a tropical storm on Wednesday as it lost strength. The storm first came ashore on Tuesday and took a north-eastern path into northern Texas and Oklahoma. The rains could cause rivers already swollen by torrential rains last month to overflow again.

"This event is not over," Texas Governor Greg Abbott said, adding that "there could be some potential tornadoes".

A 62-year-old woman died on Wednesday when she lost control of her car on a rain-soaked highway near the central town of West, a state trooper said.

The heavy rains shut roads and snarled transportation in the Houston and Dallas areas, two of the largest US metropolitan areas.

Nearly 500 flights had been cancelled at Dallas and Houston airports, some of the busiest in the United States, tracking service FlightAware.com said.

The National Weather Service issued a flash flood watch for an area from the Texas coast into Illinois, affecting more than 20 million people.

REUTERS