A tropical depression formed Sunday off the East Coast and could hit the Outer Banks as a tropical storm by Tuesday, while a separate system threatens parts of the flood-ravaged Gulf Coast this week.

Tropical Depression 8 could develop into Tropical Storm Hermine (her-MEEN), the National Hurricane Center said Sunday. A tropical storm watch may be posted later.

The system was 355 miles southeast of Cape Hatteras, N.C., with winds of 35 mph and moving west at 9 mph.

Drenching showers, thunderstorms and rough surf will threaten the Carolina coast this week, AccuWeather meteorologist Ed Vallee said.

Another system might bring additional rain to the Gulf Coast, including Louisiana, which is still reeling from this month’s deadly floods that killed 13 people and destroyed thousands of homes.

The Gulf Coast threat comes from a swirling mass of clouds and thunderstorms south of Florida (labeled by the hurricane center as “Invest 99L”) that’s been watched closely for 10 days by meteorologists. As of Sunday afternoon, the system had a 60% chance of developing into a tropical depression or hurricane within the next two days and an 80% chance within the next five days, the center said.

The storm remains a rain threat to the entire Gulf Coast, as various forecasts have it tracking toward Texas, Louisiana or Florida’s west coast.

“Welcome to another edition of “as 99L turns,” the National Weather Service in New Orleans said in an online forecast.

Heavy rain could soak the Gulf Coast even if the system doesn’t get a name, according to weather.com, as did the unnamed system this month that triggered Louisiana’s epic flooding.

In Pensacola, officials with Escambia County issued a statement Sunday encouraging residents “to double-check their storm supplies and began basic storm preparations.”

The strongest storm currently in the Atlantic Ocean, Hurricane Gaston, poses no threat to land. The Category 3 storm with winds at 115 mph is the season’s first major hurricane, spinning hundreds of miles east of Bermuda and is to continue moving out to sea.

Yet another weather system is forecast to move off the west coast of Africa and begin a slow trek across the Atlantic by mid-week. The hurricane center gives that system a 50% chance of becoming a tropical depression or storm within the next five days.

In the central Pacific Ocean, Tropical Storm Madeline should approach Hawaii this week, moving over or near the Big Island by Wednesday, according to the Central Pacific Hurricane Center. As of late Sunday, the storm had winds of 50 mph and was about 970 miles east-southeast of Hilo, Hawaii.

Contributing: Pensacola News-Journal