Hurricane Helene has intensified into a Category 2 storm, with the National Hurricane Center (NHC) forecasting “significant further strengthening” before it reaches the Gulf Coast of Florida late Thursday night.

The NHC stated in its advisory at 8 a.m. ET on Thursday that Floridians should quickly finalize preparations to safeguard themselves and their properties ahead of the storm’s arrival.

As of Thursday morning, Helene was situated approximately 320 miles southwest of Tampa and was advancing to the north-northeast at around 12 mph. This trajectory is expected to maintain a “notable increase in forward speed” over the next 24 hours.

The storm’s maximum sustained winds have risen to nearly 100 mph, with even stronger gusts. With predictions for further strengthening, Helene is anticipated to make landfall as a major hurricane along Florida’s Big Bend coast.

The projection indicates Helene will traverse the eastern Gulf of Mexico on Thursday, landing on the Big Bend coast by Thursday evening or early Friday morning. Rainfall estimates suggest 8 to 12 inches in areas where the storm makes landfall, with some isolated spots possibly accumulating up to 2 feet, according to AccuWeather.

After making landfall, Helene is expected to shift northwest and then slow its pace over the Tennessee Valley on Friday and Saturday.

“Although weakening is anticipated post-landfall, Helene’s rapid forward movement will allow for strong and damaging winds, particularly in gusts, to reach well inland across the southeastern U.S., including the elevated areas of the southern Appalachians,” the advisory noted on Thursday morning.

The hurricane’s trajectory will affect populated regions such as Tallahassee, Florida, and Atlanta, as well as Asheville, North Carolina, as reported by the National Oceanic and Atmospheric Administration.

Catastrophic Storm Surge from Helene Poses Risks

Helene is expected to bring a historic storm surge, particularly in the area where Florida’s coastline curves around the northeastern Gulf of Mexico, known as the “Big Bend.” Residents in the Gulf Coast, and especially in this section, are familiar with the challenges associated with floodwaters.

The NHC warned on Wednesday that the “catastrophic and deadly storm surge” could rise 15 to 20 feet above ground in certain coastal areas.

Along almost the entire west coast of Florida, warnings for potential surges of up to 12 feet have been issued, as noted by Jamie Rhome, the center’s deputy director.

“The size of this storm will displace a significant amount of water,” Rhome stated. “In terms of storm surge, the size of the hurricane matters more than its intensity, which can be a difficult concept for some to grasp.”

Helene is massive, with hurricane-force winds extending up to 25 miles from its center, and tropical storm-force winds reaching out to 345 miles.

Helene marks the fifth hurricane of the 2024 Atlantic hurricane season. By late Thursday, it will become the fifth consecutive year that a major hurricane has impacted the U.S. mainland, as per Colorado State University’s hurricane expert Phil Klotzbach.

What Causes a Storm Surge?

Watches for hurricanes and storm surges have been issued for much of Florida’s Gulf Coast as Tropical Helene approaches.

Storm Helene is expected to develop into a significant hurricane as it travels north from the Caribbean into the Gulf of Mexico.

The rapid increase in water levels, accompanied by already strong and high waves, could result in severe impacts that might displace homes from their foundations and inundate low-lying regions far inland.

In the ocean, winds from the hurricane push water toward the storm’s center. Rather than building up, this water spirals down and flows outward.

As some of the water is forced down, more of it is pushed out into the ocean while some moves towards the shore.

When the storm gets closer to land and encounters shallow waters, the ocean floor restricts the outward flow of water, which results in a surge that floods the land.

The characteristics of the ocean floor and the coastline significantly affect the storm surge height—the difference in water levels when a storm approaches. In the Gulf of Mexico, the broad, gently sloping continental shelves increase vulnerability to water accumulation along the coast. Conversely, along the Atlantic coast, the narrower, steeper shelves result in a lower surge.

Estimated Storm Surge Heights Along the Gulf Coast

The hurricane center has provided estimates of possible surge heights for various coastal sections:

• Carrabelle to Suwannee River: 15-20 feet
• Apalachicola to Carrabelle: 10-15 feet
• Indian Pass to Apalachicola: 6-10 feet
• Mexico Beach to Indian Pass: 3-5 feet
• Suwannee River to Chassahowitzka: 10-15 feet
• Chassahowitzka to the Anclote River: 8-12 feet
• Anclote River to Middle of Longboat Key: 5-8 feet
• Tampa Bay: 5-8 feet
• Middle of Longboat Key to Englewood: 4-7 feet
• Englewood to Flamingo: 3-5 feet
• Charlotte Harbor: 3-5 feet
• Florida Keys: 1-3 feet
• From Flagler/Volusia County Line to South Santee River, South Carolina: 1-3 feet