Miami ? 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 today, which prompted the warning from north of Jupiter to Titusville, according to the National Hurricane Center. It was expected to bring tropical storm conditions – winds of at least 39 mph – to the state by Wednesday morning.

“The primary concern is very heavy rains,” hurricane specialist Richard Pasch said. Five to 10 inches were expected over the next few days, with some isolated areas possibly getting 15 inches. The rain was expected to hit areas affected by last year’s Hurricanes Frances and Jeanne.

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

Two other storms were out in the open ocean Tuesday. Tropical Storm Nate was expected to strengthen south of Bermuda, while Hurricane Maria weakened on its way to the colder waters of the north Atlantic.