NEW ORLEANS — A slow-moving tropical depression was slogging toward the U.S. Gulf coast Friday, packing walloping rains that could drench the region with up to 20 inches (50 centimeters).

In Louisiana, Gov. Bobby Jindal said he was concerned about the serious threat of flash flooding in his state and he declared a state of emergency Thursday. After devastating Hurricane Katrina in 2005, nothing is being taken for granted.

The depression could become Tropical Storm Lee, the 12th named storm of the Atlantic hurricane season.

Tropical storm warnings were issued from Mississippi to Texas including New Orleans. The National Hurricane Center said the system will dump large amounts of rain over southern areas of Louisiana, Mississippi and Alabama through Sunday.

Forecasts were for landfall over the weekend on southern Louisiana's coast. The depression had maximum sustained winds of 35 mph (56 kph) early Friday. It was moving northwest near 2 mph (3 kph), with the hurricane center predicting slow, possibly erratic motion.

"Wow. This could be a very heavy, prolific rainmaker," National Weather Service meteorologist Frank Revitte said.

According to a hurricane center chart, maximum sustained winds could reach 60 mph (96 kph) by Saturday, lower than hurricane strength of 74 mph (119 kph).

As hurricane season is hitting its peak in the Atlantic, storm watchers were monitoring three disturbances. Besides the Gulf depression, Tropical Storm Katia was spinning in open waters. It weakened from a hurricane Thursday, though forecasters said it would again grow stronger.

It was about 750 miles (1,205 kilometers) east of the Caribbean's northern Leeward Islands and moving west-northwest near 15 mph (24 kph) with maximum sustained winds early Friday near 70 mph (110 kph). It could regain hurricane strength this weekend and was expected to pass north of the Caribbean. Forecasters say it's too early to tell if it would hit the U.S.

In yet another system, a slow-moving low pressure system about 450 miles (725 kilometers) south of Nova Scotia, Canada, had a 60 percent chance early Friday of becoming a tropical cyclone in the next two days.

They all come on the heels of Hurricane Irene, which brought destruction to the Caribbean and the U.S. Eastern Seaboard, killing more than 50 people.