Potential Tropical Cyclone Six forms in Gulf; tropical storm watch issued for Mexico

Potential Tropical Cyclone Six has formed over the waters of the Gulf of Mexico and tropical storm watches were issued for parts of Mexico, the National Hurricane Center said Sunday.

The system is expected to become a tropical storm Monday as it moves north along the western coast of the Gulf of Mexico, the hurricane center said in an 11 p.m. ET update. It is likely to strengthen beginning Tuesday.

It is then forecast to become a hurricane before it hits the northwestern Gulf Coast midweek.

Tropical storm watches have been issued for parts of northeastern Mexico, from Barra del Torro northward to the mouth of the Rio Grande, and from Port Mansfield, Texas, south to the mouth of the Rio Grande.

The hurricane center said additional storm watches or warnings might be necessary for areas near the southern Texas coast and along the Louisiana coast later Sunday or Monday.

The system was about 320 miles south of the mouth of the Rio Grande and had maximum sustained winds of 50 mph, according to the update.

The storm is moving northwest at 5 mph, the hurricane center said.

"A slow northwestward to northward motion is expected over the next day or so, followed by a faster motion to the northeast beginning late Tuesday," the hurricane center said. "On the forecast track, the disturbance is expected to move just offshore of the northern Gulf Coast of Mexico through Tuesday, and approach the Louisiana and Upper Texas coastline on Wednesday."

The hurricane center expects Potential Tropical Cyclone Six to bring heavy rain and the risk of flash flooding from the coast of northeastern Mexico to parts of coastal Texas and Louisiana through Thursday, with expected rainfall totals of 4 to 8 inches and up to 12 inches possible in some areas.

Minor coastal flooding is possible along Mexico's coast, as well.

“While it is too soon to pinpoint the exact location and magnitude of impacts, the potential for life-threatening storm surge and damaging winds are increasing for portions of the Upper Texas and Louisiana coastlines beginning Tuesday night,” the hurricane center said.

This article was originally published on NBCNews.com