About 120 miles of Florida's Atlantic coast were under a tropical storm warning Tuesday as a new system formed just offshore and threatened to dump up to 15 inches of rain in parts of the state.

The tropical depression could strengthen into Tropical Storm Ophelia by Wednesday, which prompted the warning from north of Jupiter to Titusville, according to the National Hurricane Center. It is expected to bring tropical-storm conditions -- with winds of at least 39 mph -- to the state by Wednesday morning.

"The primary concern is very heavy rains," said hurricane specialist Richard Pasch. Five to 10 inches were expected over the next few days, with isolated areas possibly getting 15 inches.

The rain was expected to hit areas affected by last year's Hurricanes Frances and Jeanne. Much of the region has recovered, but some homes remain covered in tarps as owners await new roofs.

Emergency management officials in St. Lucie and Indian River counties said they were monitoring the storm for developments but were not taking any protective action.

"Right now we're looking at this as a rain event," said Nathan McCollum, emergency management coordinator for Indian River County.

At 8 p.m. Eastern time, the storm had top sustained winds of about 30 mph and was centered about 165 miles southeast of Cape Canaveral.

Two other storms hovered over the ocean far from land. Tropical Storm Nate was expected to strengthen south of Bermuda, while Hurricane Maria weakened on its way to the North Atlantic.

Nate, the 14th named storm of the season, was centered about 275 miles south-southwest of Bermuda with top sustained winds near 60 mph. Forecasters said it could reach hurricane strength, with winds of at least 74 mph, by Wednesday.

It was expected to eventually turn to the northeast over the next 24 hours, forecasters said.

"Perhaps by the end of the work week it could be posing a threat to Bermuda, but not the U.S.," said hurricane specialist Stacy Stewart.