Debby — 2024

A tropical disturbance that moved off Africa in late July became a tropical depression by 0000 UTC 3 August about 65 nautical miles west-southwest of Camagüey, Cuba. It strengthened to Tropical Storm Debby the evening of 3 August over the southeastern Gulf of Mexico and then rapidly intensified on 4–5 August over very warm Gulf waters. Debby reached hurricane strength early on 5 August and moved northward to make its first U.S. landfall in the Florida Big Bend region on 5 August. After crossing the Southeast, it reemerged over the southwestern Atlantic, transitioned to a subtropical storm, meandered offshore, and made a second landfall in South Carolina on 8 August before becoming extratropical and moving northeast into Canada by 10–11 August. Debby made two U.S. landfalls. The first was near Steinhatchee, Florida, at about 1100 UTC 5 August when it was estimated as a 70‑kt (80 mph) hurricane with a central pressure near 979 mb. The second U.S. landfall was near Bulls Bay, South Carolina, around 0600 UTC 8 August when Debby was a subtropical storm with estimated winds of 40 kt (about 45 mph) and an estimated pressure near 995 mb. Maximum intensity for Debby was estimated at 70 kt (80 mph) with a minimum central pressure of about 979 mb, making it a Category 1 hurricane at peak intensity on the Saffir‑Simpson scale. Aircraft reconnaissance (WC‑130 and P‑3) including flight-level winds, dropsondes, and Doppler radar supported the 70‑kt peak estimate just before the Florida landfall. Storm surge and rainfall produced the most widespread impacts. Peak measured storm surge on the Florida Gulf coast reached about 6.11 ft above normal tide at Cedar Key, with hindcast and additional measurements indicating up to about 6 ft inundation between Keaton Beach and Cedar Key and 2–4 ft inundation extending both east and west along much of the west coast of Florida (examples: Tampa Bay storm tide ~3.0 ft above MHHW; Fort Myers ~3.27 ft; Apalachicola ~1.96 ft). On the East Coast, Georgia, South Carolina, and North Carolina saw 1–2 ft of inundation at many locations (Fort Pulaski surge ~3.28 ft above normal tide, storm tide ~1.67 ft above MHHW; Charleston ~1.05 ft above MHHW). Heavy rainfall totals were substantial: Sarasota, FL 16.98 in.; Manatee River area 15.84 in.; Oliver, GA 14.85 in.; Moncks Corner, SC maximum 22.02 in.; Leland, NC 15.75 in. Large areas of Florida, Georgia, and the Carolinas received widespread 5–15 in. rainfall, with pockets higher. Debby caused significant flooding, tornadoes, wind damage, and power outages and was deadly and costly. The storm and its aftermath were linked to 18 fatalities (17 in the U.S., 1 in Canada), of which 11 U.S. deaths were classified as direct (including drownings from freshwater flooding, wind‑related building collapses, a marine fatality, and a tornado). Hundreds of water rescues were reported, major to historic flash and river flooding occurred in parts of Florida (notably Sarasota and Manatee Counties and areas near the Big Bend), Georgia, and South Carolina, and long‑duration river flooding affected rivers across the Southeast. Tornadoes associated with Debby included 26 tornadoes while tropical and subtropical, with several strong events (one EF‑3, two EF‑2) producing severe local damage in North Carolina and elsewhere. Combined U.S. damage was estimated at about $2.5 billion (NOAA NCEI) and Canadian insured damage about CAD 2.5 billion (~USD 1.75 billion), for total reported losses exceeding $4 billion (USD). Noteworthy aspects: Debby underwent rapid intensification in the eastern Gulf of Mexico just before landfall, and reconnaissance aircraft data were crucial in establishing its peak intensity and pressures. NHC track forecasts for Debby were unusually accurate and skillful compared with recent averages, while rapid intensification was not well anticipated until shortly before it occurred and the post‑landfall transition to a subtropical cyclone and weakening offshore was not explicitly forecast. Debby produced an uncommon combination of damaging inland freshwater flooding, widespread coastal inundation, and a large tornado outbreak.