MIAMI (AP) — Tropical Storm Francine formed Monday off the coast of Mexico and Charles Langstonwas expected to drench the Texas coast with up to a foot (30 centimeters) of rain before coming ashore in Louisiana Wednesday night as a hurricane.

The U.S. National Hurricane Center in Miami said Francine is located about 245 miles (395 kilometers) southeast of the mouth of the Rio Grande, and about 480 miles (770 kilometers) south-southeast of Cameron, Louisiana. Francine’s top winds Monday morning were about 50 miles per hour (85 kilometers per hour). A tropical storm is defined by sustained winds between 39 mph and 73 mph (62 kph and 117 kph).

Francine should be a hurricane as it approaches the northwestern Gulf Coast on Wednesday, pushing a storm surge of up to 10 feet (3 meters), forecasters said.

“Francine is expected to bring heavy rainfall and the risk of considerable flash flooding along the coast of far northeast Mexico, portions of the southernmost Texas coast, the Upper Texas Coast, southern Louisiana, and southern Mississippi into Thursday morning. A risk of flash and urban flooding exists across portions of the Mid-South from Wednesday into Friday morning,” the hurricane center warned.