(NewsNation) — Several parts of Florida are under alert as the state braces for Tropical Storm Helene to strengthen into a major hurricane before making landfall in the United States.

Florida Gov. Ron DeSantis has declared a state of emergency in 41 counties. On Tuesday morning, the storm was sitting in the Caribbean Sea near Cuba and the Cayman Islands and was expected to grow into a hurricane in the coming days, according to the National Hurricane Center.

Brad Reinhart, a senior hurricane specialist, said in a phone interview with the Associated Press that Helene could become a Category 3 by the time it reaches the Gulf Coast.

“People in the Florida Panhandle and the west coast of Florida certainly need to pay close attention,” Reinhart said. “It’s a pretty aggressive forecast for intensification over the next few days. … People need to remain on high alert.”

This is what you need to know before Helene makes its way to land:

What areas are under a hurricane watch for Helene?

Watches and warning have been issued for parts of the Yucatan Peninsula, western Cuba, Grand Cayman and Florida, according to the Weather Channel.

In Florida, storm surge watch was in effect for Indian Pass southward to Flamingo; Tampa Bay; and Charlotte Harbor. This means there’s a possibility of life-threatening “inundation” in those areas for the next 48 hours.

The Dry Tortugas; Grand Cayman Island; Rio Lagartos to Tulum, Mexico; the Lower Florida Keys west of the Seven Mile Bridge and the Cuban provinces of Artemisa, Pinar del Rio and the Isle of Youth are under a tropical storm warning. A tropical storm warning indicates tropical storms conditions are expected in the next 24-36 hours.

The Middle Florida Keys west of the Seven Mile Bridge to the Channel 5 bridge; Flamingo to south of Englewood; and west of Indian Pass to Walton Bay County line are under a tropical storm watch, so these conditions are possible in the areas within 48 hours.

A hurricane watch is in effect for: Cabo Catoche to Tulum, Mexico; the Cuban province of Pinar del Rio; Englewood to Indian Pass; and Tampa Bay. Hurricane watches mean that hurricane conditions are possible. They are usually issued 48 hours before forecasters predict the first occurrence of tropical storm-force winds.

In the coming days, people in regions under storm watches and warnings should be prepared to lose power, Lisa Bucci, a hurricane specialist, told AP. Bucci added that those in affected areas should stock up on enough food and water for at least three days.

“Now is the time to start preparing. If you’re in an evacuation zone, you should evacuate,” Bucci said. “Don’t be fooled by the way the storm looks at the moment. We are expecting it to rapidly intensify.”

When is Helene expected to hit Florida?

Helene is expected to get closer to Cancún, Cozumel and western Cuba late Tuesday into early Wednesday, according to the National Hurricane Center.

Parts of Cuba could see up to 12 inches of rain and flash flooding as a result. By Wednesday, it will likely be a hurricane in the Gulf of Mexico, forecasters said, with heavy rain and strong winds still hitting western Cuba.

Then, it is forecast to make landfall Thursday across the Florida Gulf Coast.

As of Tuesday morning, Helene was about 150 miles west of Grand Cayman, with maximum winds of 45 mph.

The Associated Press contributed to this report.