CNN
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Florida is bracing for what could be the most severe hurricane of the season in the United States. A thunderstorm system is gaining strength in the Caribbean before bringing potentially life-threatening storm surges and hurricane-force winds to the Southeast later this week.

The system will gain momentum and is expected to rapidly intensify into Hurricane Helene as it approaches the coast. It will continue to hurl wind, rain and storm surge southeastward before it is expected to make landfall in Florida, said the National Hurricane Center, which called the hurricane a “potential tropical cyclone nine.”

Florida Governor Ron DeSantis has declared a state of emergency in 41 of the state's 67 counties to accelerate preparations and coordination between the state and local governments regarding the impacts of the storm.

With little time to prepare, Tampa General Hospital began building a 10-foot-high flood barrier around the facility on Monday due to the risk of storm surge and changes in the storm's track.

On Monday, the potential cyclone was a collection of showers and thunderstorms raging across the far western Caribbean. The NHC predicts the system will rapidly intensify and is likely to become a hurricane by Wednesday night, eventually reaching Category 3 strength.

The last storm to make landfall in the United States as a Category 3 hurricane, Idalia, also hit the Florida coast in August last year, packing winds of 200 km/h and causing a record-breaking storm surge from Tampa to the Big Bend.

Idalia experienced a period of rapid intensification over the warm waters of the Gulf of Mexico, with sustained winds increasing by 55 mph within 24 hours.

A tropical storm warning was issued Monday afternoon for Florida's Dry Tortugas and parts of the Keys, and a storm surge warning was issued Monday evening for areas from Bonita Beach to Flamingo, where a storm surge warning is also in effect.

Further warnings will be issued for the USA in the coming days. A possible landfall in Florida is expected as early as Thursday evening.

The National Hurricane Center is reporting landfall in Florida's Big Bend region, but CNN meteorologist Mary Gilbert says everyone from Florida's Gulf Coast to eastern Louisiana should be on alert this week.

Where the system ultimately makes landfall, strong, potentially damaging winds and storm surge are likely. The system will also stir up seas in the Gulf and could produce rough surf and dangerous rip currents across much of the basin, especially later this week.

“Strengthening is expected over the next few days. The system is expected to become a hurricane on Wednesday and continue to strengthen on Thursday as it moves across the eastern Gulf of Mexico,” the NHC said in an 11 p.m. warning on Monday.

Confidence in the exact trajectory of the system will increase after its formation, since without a fixed center, forecast models have difficulty determining exactly where the system might move.

This stormy weather will potentially cause flooding in parts of Central America, Mexico, Cuba and Jamaica as it attempts to form into a tropical system. Hurricane and tropical storm warnings have already been issued for parts of Mexico and Cuba.

“Potential Tropical Cyclone Nine will bring heavy rainfall to much of the western Caribbean, causing significant flooding and mudslides throughout western Cuba,” the National Hurricane Center said.

In its forecast discussion on Monday at 5 p.m. ET, the NHC warned that the expansion of the system over the record-warm Gulf of Mexico would have far-reaching consequences for the United States.

The “impacts of storm surge, wind, and rain will extend well beyond the center, particularly east of the system. In addition, the high speed at which the system is approaching the coast will likely cause gusty winds to extend further inland after landfall, reaching parts of the southeastern United States,” it said.

Heavy rains are possible across much of the Southeast starting midweek. According to the Weather Prediction Center, there is a Category 2 to 4 flood risk for Thursday across much of Florida, Georgia, Alabama and parts of the Carolinas.

Helene could also bring strong winds and torrential rain to much of Georgia and the Carolinas through Friday, potentially leading to dangerous flooding and significant power outages.

“Heavy rainfall is likely to cause locally significant flash flooding and urban flooding in parts of Florida, with isolated flash flooding and urban flooding possible in the Southeast, southern Appalachians, and Tennessee Valley from Wednesday through Friday. Minor to isolated moderate river flooding is possible,” the National Hurricane Center said.

Helene would be the fourth hurricane to make landfall in the United States this year and the fifth hurricane to devastate Florida since 2022.

The repeated setbacks have brought the insurance market in Florida to the brink of collapse. Due to the increasing risk of extreme weather events as a result of climate change, insurers are withdrawing from the state.