Tropical storm watches in effect for parts of Louisiana and Texas

The big picture: Tropical storm watches were issued Tuesday from Sargent, Texas, to Morgan City, Louisiana.

• The storm, currently known as Invest 90L, is expected to dump 4 to 8 inches of rain in parts of Texas, Louisiana, Mississippi, Alabama and Florida, forecasters warn.
• Some spots could get up to 12 inches through Thursday, leading to potentially life-threatening flash flooding.
• Flash flooding was already reported in Picayune, Mississippi, on Tuesday, where more than 5 inches of rain has already fallen, the National Weather Service says.

By the numbers: As of 1pm, the system was 55 miles southwest of Corpus Christi, Texas, and moving northeast at 6 mph.

• It has winds of 30 mph and is expected to strengthen. Forecasters expect peak winds of 40 mph, just above the 39 mph threshold required for tropical storm status.
• The system is expected to hug Texas' coast before moving inland late Wednesday or early Thursday. See the latest track.
• Hurricane Hunter aircraft were scheduled to fly into the system Tuesday afternoon to gather data on its structure and strength.

Zoom in: In New Orleans metro, 2 to 3 inches of rain are likely through Saturday morning, but some areas could get up to 8 inches, the National Weather Service in Slidell says.

• Baton Rouge could get up to 20 inches in a worst-case scenario. The entire region is under a flood watch.
• Residents should expect periods of heavy rain daily this week. Rainfall rates could exceed 3 to 4 inches per hour.
• Pumps in Orleans and Jefferson parishes generally can handle 1 inch of rain in the first hour and then a half-inch per hour after that.
• Storm surge up to 4 feet is possible along Louisiana's coast, NHC says.