Isaac is drenching Louisiana and Mississippi but is weakening as it trudges roughly north over land and should lose its tropical storm status by Thursday night.

The U.S. National Hurricane Center says Isaac's wind strength should drop below 39 mph to become a tropical depression as the storm's center heads for Arkansas and Missouri on Friday.

Isaac's center bypassed New Orleans and its newly fortified levees as a hurricane Wednesday but flooded areas to the city's north and south, where people had to be evacuated or rescued.

Isaac had top sustained winds of 45 mph early Thursday as its center moved over southern Louisiana. It was still packing heavy rains that threatened lowland flooding through Friday in Louisiana, Mississippi, southwest Alabama and Arkansas.