High water floods St. Claude Avenue in the Bywater neighborhood following heavy overnight rain in New Orleans, La., Sunday, May 12, 2019.

Heavy rains and "widespread flash floods are expected" across south Louisiana and surrounding states, according to the National Weather Service. A flash flood watch in south Louisiana is in effect until Thursday night.

A tropical disturbance in the Gulf of Mexico is expected to move across Texas and into southwest Louisiana today. The risk of flash flooding will shift eastward through Friday.

The National Weather Service in New Orleans updated its rain projections Wednesday morning.

New Orleans and Lafayette are expected to get up to 4-6 inches through Friday. Baton Rouge is expected to get between 3-4 inches.

Lafayette and Baton Rouge are both at moderate risk of flash flooding today, while New Orleans is at a slight risk.

On Thursday, Baton Rouge and New Orleans are at a moderate risk.

The disturbance failed to develop into the second named storm of hurricane season but will still bring heavy rainfall to much of the southern U.S.