A major hurricane is forecast to slam into Florida’s Gulf Coast on Thursday, unleashing destructive winds, a potentially “life-threatening” storm surge and dangerous amounts of rain. The tropical storm, which the National Hurricane Center named Helene on Tuesday morning, is predicted to rapidly gain strength over the exceptionally warm waters of the Gulf of Mexico, becoming a hurricane by Wednesday morning.

Hurricane warnings were issued Tuesday evening along the Florida coast from the Panhandle’s Mexico Beach, which was devastated by Hurricane Michael in 2016, to Anclote River, which is just north of Tarpon Springs and Tampa.

Florida Gov. Ron DeSantis (R) declared a state of emergency in 41 of the state’s 67 counties ahead of the storm — both in the state’s Panhandle and along its west coast. Mandatory evacuation orders have been issued for parts or all of at least ten coastal counties between the Panhandle and the peninsula’s west coast. Florida State University in Tallahassee said it will close its campus between Wednesday and Sunday, among other school closures in the state.

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The Hurricane Center, which predicts the storm to reach Category 3 intensity, cautioned Helene could produce dangerous storm surge inundation along Florida’s Big Bend and the entire west coast of the peninsula. It said the Big Bend faced the “highest inundation levels” and also “damaging hurricane-force winds.”

A storm surge warning spans the area from Flamingo in far southwest Florida to Indian Pass, which is to the west of Apalachicola in the Panhandle. The warning area includes Tampa Bay and Charlotte Harbor, which is to the north of Fort Myers.

If a worst-case scenario is realized, a storm surge could push water to the height of second-floor windows in the Big Bend, or at least 10 to 15 feet above normally dry land. The risk of surge impacts in Tampa are increasing, where water levels could rise 5 to 8 feet or more, resulting in significant inundation.

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In addition to probably becoming the strongest hurricane to make landfall in the United States this year, Helene is also poised to become the sixth hurricane to hit Florida since 2022 and potentially the ninth major hurricane, rated Category 3 or higher, to make landfall along the Gulf Coast since 2016.

Helene’s impacts will extend far inland as well across the southeast, the southern Appalachians and the Tennessee Valley. The storm’s swift forward speed will allow it to penetrate farther inland before weakening, leading to greater impacts — including the risks of heavy rainfall and flooding, isolated tornadoes and damaging gusts.

In addition to its potential to reach Category 3 or higher strength, Helene is predicted to be a larger-than-normal hurricane, or in the 90th percentile for size, according to the Hurricane Center, meaning its impacts will affect areas potentially hundreds of miles away from the storm center.

Where is the storm now, and what is its short-term outlook?

Helene was centered over the northwestern Caribbean on Tuesday night, about 145 miles south-southwest of the western tip of Cuba. Packing maximum sustained winds of 60 mph — a 15 mph increase from late in the morning, the storm was headed to the west-northwest at 10 mph.

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In its 11 p.m. update Tuesday, the Hurricane Center said storm was becoming “better organized” with a “more symmetrical-looking cloud pattern,” which may signal the beginning of a period of rapid strengthening.

The intensification is predicted as the storm moves over areas of record ocean heat content — or hurricane fuel. Water temperatures are between 86 and 90 degrees.

The Hurricane Center’s forecast for intensification is the fastest it has made for such a developing storm.

Where and when is it likely to come ashore?

The system is most likely to come ashore in Florida’s eastern Panhandle or Big Bend on Thursday evening. That said, there is a chance it could nudge farther east, which would mean greater impacts for Tampa.

The system is being “captured” by a pocket of a dip in the jet stream over the lower Mississippi Valley. That’s what will tug it northward as it swings ashore.

How strong could it be?

With hot water temperatures, weak high-altitude winds and ample moisture at most levels of the atmosphere, the ceiling is high — meaning that assuming Helene remains unperturbed, it could reach Category 3 or 4 strength.

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There are relatively few limiting factors. The most obvious would be if the system takes a long time to develop a core. If that’s the case, it might have a tougher time organizing in the short term and would have a lesser window over the gulf to strengthen. However, a low-end scenario would still entail a Category 1 or 2 hurricane.

Another potential limiting factor would be outflow, or exhaust air, from John — the remnants of a Pacific hurricane — which could fan over the gulf. If that’s the case, it might limit how strong Helene could get.

What are the impacts of greatest concern in Florida?

A dangerous storm surge of 10 to 15 feet isn’t impossible where the hurricane’s core makes landfall, especially to the east, or right, of the center. That’s also where winds will be strongest onshore and will most efficiently pile water against the coastline.

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Damaging gusts over 110 mph are possible within the core of the storm at the immediate coastline. In Tampa, gusts over 70 mph are possible, and a few gusts of 80 mph can’t be ruled out in Ocala. Perry might see gusts to 90 mph or greater.

A general 4 to 8 inches of rain is expected across central and north Florida, bringing the threat of flooding.

While an isolated tornado can’t be ruled out, the risk of tornadoes — mainly to the east of where the center comes ashore — is marginal.

What areas north of Florida need to be concerned about this storm?

Because of the storm’s large size and fast speed, strong winds capable of producing downed trees and power outages could extend well inland. Southern Georgia and far southeastern South Carolina might also see gusts of 80 mph as Helene’s remnant core breezes through overnight Thursday into Friday. But the most widespread inland hazard will probably be flooding rainfall, as the storm will be drawing record levels of moisture northward.

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The Hurricane Center projects 4 to 8 inches of rain over a broad area from Florida’s west coast to the southern Appalachians, with some areas seeing up to a foot. It forecasts the potential for “considerable flash and urban flooding.” Some of the heaviest rain and most serious flood potential could occur in the western Carolinas on Friday.

Tornadoes could occur in some of the heavy rain bands that pivot ashore and progress northward Thursday and Friday, mainly east of the storm center.

The remnants of the storm could meander over the mid-South and even drift as far west as Missouri into the weekend and early next week, producing scattered downpours.