Hurricane Helene Summary: Catastrophic surge, inland flooding

Hurricane Helene barreled into Florida with catastrophic storm surge and damaging winds, then dumped copious rainfall inland over the Southeast, causing extreme flash flooding and record river flooding in the Carolinas and Tennessee.

A historic landfall: Helene made landfall at 11:10 p.m. EDT on September 26 about 10 miles (16 kilometers) west-southwest of Perry, Florida, at a Category 4 intensity with winds of 140 mph (230 km per hour) and a pressure of 938 millibars, according to the National Hurricane Center.

Helene was the strongest hurricane ever to make landfall in the Big Bend region of Florida, stronger than 2023’s Idalia, which made a Category 3 landfall with winds of 110 mph (180 km/h) and a pressure of 950 millibars, and a hurricane from 1896 Cedar Keys with winds of 125 mph.

Helene was also the third hurricane to make landfall in the Big Bend region of Florida in just under thirteen months. Three of the last five hurricanes to make landfall on the continental US have done so in this Big Bend region.

Storm surge: Based on post-storm modeling, peak storm surge is estimated to have reached more than 15 feet above ground in the Florida Big Bend region. The area will be inspected at a later date to reveal the actual measured storm surge heights.

In Cedar Key, an estimated flood of 11 feet (3.3 meters) and a peak surge of 11 feet (3.33 meters) appeared to surpass the city’s record surge from an 1896 hurricane.

H​elene’s surge also appeared to be modern record levels for the Tampa-St. Saint Petersburg metro area, with flooding of 1.8 to 2.5 meters above ground level, measured by tide gauges. Clearwater Beach surpassed the record set by the March 1993 superstorm, while St. Petersburg bettered the record set by Hurricane Elena in 1985.

Significant flooding was also reported at Ft. Myers Beach and Naples, where gauges measured 4 to 5 feet of flooding. According to a ham radio operator, water was observed 5 to 6 feet above normal levels in the Punta Gorda Canal Network.

Rainfall floods: The combination of heavy rain the day before Helene – something meteorologists call a “predecessor rain event” – and Helene’s rain on hilly and mountainous terrain caused catastrophic flash flooding and river flooding from Georgia to western Carolina, eastern Tennessee and southwestern Virginia .

Record flood levels have been recorded at at least seven locations in North Carolina and Tennessee, including the Pigeon River in Newport, Tennessee, the French Broad River in Rosman, North Carolina, and the Swannanoa River in Biltmore (near Asheville), North Carolina. In parts of western North Carolina, records that had stood since the “Great Flood” of July 1916 were broken.

Floodwaters flowed through parts of Asheville and Boone, North Carolina. They washed at least one section of Interstate 40, flooded a hospital in Tennessee prompting rooftop helicopter evacuations and compromised a dam, forcing the evacuation of Newport, Tennessee.

At one point on September 27, the National Weather Service had more than 20 flash floods – the highest warning level – in effect from metro Atlanta, Georgia, into southwestern Virginia. That was the most spent on any day in at least 13 years.

In parts of Florida, Georgia, North Carolina and South Carolina, rainfall totals exceeded a foot. The highest total is almost 30 inches near Busick, North Carolina. Asheville, North Carolina broke the two-day rainfall record (9.87 inches), which had stood for almost 106 years. Atlanta also broke the 48-hour rainfall record (11.12 inches) that had stood since 1886.

Damaging winds, disruptions: The eyewall, home to a hurricane’s most intense winds, prompted a rare “extreme wind warning,” a high-end warning issued only for Category 3 or stronger hurricane eyewalls to warn those in its path to take shelter for these damaging winds, as if a A tornado warning was issued.

Helene’s intensity at landfall and rapid forward speed allowed high winds to penetrate much further inland than is typical of a landfalling hurricane.

Wind gusts of 90 to 100 mph were clocked in several locations, peaking in Perry, Florida (99 mph), as well as between Live Oak, Florida and Valdosta, Georgia. Wind gusts as high as 80 miles per hour were measured as far north as Augusta, Georgia, wind gusts as high as 70 miles per hour were measured as far north as Anderson, South Carolina, and wind gusts over 60 miles per hour were measured as far as in northern Dayton, Ohio.

On September 27, more than four million customers were without power as a result of the storm from Florida via Virginia to Indiana.

Tornadoes: Landfalling hurricanes often produce tornadoes in the outer rainbands, both before and long after landfall, and Helene was no exception.

Pending completion of National Weather Service storm surveys, more than a dozen tornadoes may have spawned before landfall (Sept. 25-26) and after landfall (Sept. 27) from Georgia to West Virginia.

Prior to landfall, a tornado in Wheeler County in southeastern Georgia destroyed a mobile home and claimed two lives.

One of the most damaging tornadoes struck Rocky Mount, North Carolina, on September 27. About 11 buildings were damaged and 15 injured in this tornado in eastern North Carolina.

Track history: The need to issue tropical storm warnings and hurricane warnings for western Cuba and Mexico’s Yucatán Peninsula prompted the NHC to begin issuing advisories on potential Tropical Cyclone Nine in the western Caribbean Sea on September 23.

The next morning, Tropical Storm Helene formed as rain showers and high winds lashed Cancun and Cozumel. Helene also produced heavy rainfall and some tropical storm surges over parts of western Cuba.

Helene subsequently became a hurricane over the southern Gulf of Mexico on September 25, then rapidly strengthened to a Category 4 hurricane on the evening before landfall on September 26.

Helene became the second major hurricane of the 2024 Atlantic hurricane season on Thursday afternoon. Early in the evening, a NOAA Hurricane Hunter mission found that maximum winds had increased to Category 4 intensity just hours before landfall.