2024 Atlantic Hurricane Season
Elijah Paciorek, Nico Sartori, Bailey Schaaf, Kaylee Sweeney, James Zinnbauer
Introduction
The 2024 Atlantic hurricane season was initially forecasted to be incredibly active on account of near-record high sea surface temperatures (SSTs) and the development of La Nina conditions in the Atlantic. Despite a prominent beginning with Hurricane Beryl from late June to early July, a large period of general inactivity occurred from July to September. Near the final week of September, however, a surge in Atlantic disturbances resulted in the development of three major hurricanes through October, two of which made landfall in the United States. This study will compare this hurricane season to previous climatological averages, analyze the larger synoptic and global environments that have been both conducive and unfavorable for the development of tropical systems, and discuss notable hurricanes that have developed.
History & Climatology
Fig. 1: Tracks of all named storms associated with the Atlantic 2024 Hurricane Season through October 10 with their names, timeline of activity, and Saffir-Simpson Scale ratings (NHC).
On average, the Atlantic hurricane season experiences fourteen named storms, seven hurricanes, and three major hurricanes. (NHC). Some of the most notable seasons were recorded in 2005, 2017, and 2020, the last of which observed a record-breaking thirty named storms and seven major hurricanes. With thirteen named storms this season, four of which were major hurricanes, the 2024 Atlantic hurricane season does not approach records by metrics of total named storms, though several records have been broken by the most notable storms of this season. In addition, four of the major hurricanes present have been rated as Category 5 storms. The season is also the second costliest in history, with ~190 billion U.S. dollars lost in damage.
The primary drivers of tropical variability in the Atlantic hurricane season are ENSO, the MJO, and SSTs. ENSO, or El Niño Southern Oscillation, affects sea surface temperatures (SSTs), where El Niño’s warmer Pacific SSTs increase vertical wind shear, limiting Atlantic hurricane formation, and La Niña’s cooler SSTs reduce shear, encouraging development. During ENSO-neutral periods, SSTs hover near average, as was the case this season, with a 60% likelihood of La Niña conditions from September to November (Climate Prediction Center). The Madden-Julian Oscillation (MJO) impacts storm activity on shorter timescales, with alternating phases every 30-60 days: an enhanced convective phase fostering storm development and a suppressed phase reducing it (Climate Prediction Center). After Tropical Storm Ernesto on August 12, the MJO’s suppressed phase led to quiet conditions until late September, despite neutral ENSO and warm SSTs which would normally support convection (Seth Borenstein, AP News). When the MJO’s enhanced phase returned, five hurricanes emerged from September 26 to October 6, including major hurricanes Helene and Milton, fueled by record-high SSTs 1.7°F above average.
Major Hurricanes
Hurricane Beryl
While not the first named storm, Hurricane Beryl was the first hurricane to form in the Atlantic during the 2024 Atlantic Hurricane season. On June 28, 2024, the storm first developed as a tropical depression with winds at 35 mph, though considerably warm ocean temperatures led to the rapid intensification of Beryl, which strengthened to a hurricane with winds of 75 mph. East of Venezuela, Hurricane Beryl continued to rapidly intensify within 24 hours from a Category 1 to a Category 4 major hurricane. Beryl made landfall on July 1 at Carriacou with sustained winds of 150 mph and devastating storm surge. Entering the Caribbean Sea, Beryl intensified to a Category 5, the earliest ever observed in the Atlantic on record, the only the second Category 5 hurricane in July, and the strongest Atlantic hurricane in July on record with peak winds of 165 mph. As it continued west, Beryl began to weaken as it encountered westerly shear. By the time it moved over the Yucatan in Mexico, it weakened to a Category 2 storm and entered the Gulf of Mexico as a tropical storm, making landfall in southwest Texas on July 8 as a Category 1 hurricane. Steered by the Jetstream, Beryl moved northeast, continuing to weaken as it transitioned to an extratropical cyclone, dissipating on July 10. Grenada’s northern and southern islands sustained catastrophic damage, and notable flooding, wind damage, and tornadoes were reported in Texas and the interior United States.
Hurricane Helene
Hurricane Helene developed in late September 2024, originating as a tropical wave in the western Caribbean. Favorable conditions, including high sea surface temperatures, low wind shear, and abundant atmospheric moisture, contributed to its rapid intensification. The storm grew swiftly into a powerful Category 4 hurricane, with sustained winds reaching 140 mph as it crossed the Gulf of Mexico. Helene made landfall in Florida’s Big Bend on September 26, delivering up to 15 feet of storm surge, extensive inland flooding as a product of its heightened precipitation, and significant wind damage. After landfall, Helene tracked northeast through Georgia into the southern Appalachians, retaining partial strength. Its interaction with a stationary front stretching from West Virginia up through the New Jersey coast stalled its movement and subsequently prolonged its impact. Moisture-laden air from Helene was continually forced upward over the Appalachian Mountains, enhancing rainfall through orographic lift, leading to rainfall totals up to 14 inches in parts of North Carolina and Tennessee. This excessive precipitation triggered flash floods and landslides, rendering some areas in these regions uninhabitable. The stalled progression and intensified rainfall made Hurricane Helene one of the most devastating storms of the 2024 season, leaving lasting damage across both coastal and inland communities, with particularly severe impacts in the vulnerable mountainous regions of the southern Appalachians.
Hurricane Milton
Hurricane Milton began as a broad low-pressure system in the western Gulf of Mexico, gaining attention as an area of tropical interest on October 5, 2024. Favorable conditions, including warm sea surface temperatures near 31℃ and minimal wind shear, spurred rapid development, and by October 6, it reached Category 1 status. Over 24 hours, Milton intensified dramatically, reaching Category 5 with 180 mph winds and a central pressure of 897 mb, the most intense storm in the Atlantic Basin since Hurricane Wilma in 2005, and the 5th most intense on record. Milton’s period of rapid intensification also marked it as the third quickest intensification in the Atlantic. As it approached Florida, increased wind shear weakened Milton to Category 3 before making landfall at Siesta Key on October 9, bringing severe winds and flooding rains. A significant tornado outbreak in southern Florida also was present as the outer rainbands passed through Florida, with ample low-level shear contributing to the development and persistence of discrete supercells. 46 tornadoes were reported, with 126 tornado warnings issued in total during the day. Milton transitioned to an extratropical cyclone as it continued eastward, eventually dissipating after it encountered a frontal boundary on October 11. Over 3.5 million lost power in the aftermath of Milton’s landfall, and the hurricane’s eastward track—a rare and direct angle on Florida—intensified impacts along the state’s west coast. The near-record breaking intensification of Milton and its subsequent impacts throughout Florida marks it as an astoundingly powerful storm, further contributing to the anomalous nature of the 2024 Atlantic Hurricane season.
Conclusion
While the 2024 Atlantic Season has followed the climatological average in total counts of named storms, its intensity has been anything but average. Despite a prolonged lull in activity due to the suppressed phase of the MJO, well above average SSTs and ENSO-neutral conditions led to the development of several significant Atlantic hurricanes. Among these, Hurricane Beryl set a record as the earliest Category 4 and 5 hurricane in June and July, Hurricane Helene brought deadly storm surge and catastrophic inland flooding, and Hurricane Milton’s rapid intensification resulted in a pressure below 900 mb, becoming the most intense hurricane since Wilma in 2005. Seasonally, the 2024 Atlantic hurricane season is the first season to feature multiple Category 5 hurricanes since 2019 and is the second costliest in history. The 2024 Atlantic hurricane season will undoubtedly be remembered for its volatility and devastation, as well as the abnormal global atmospheric and oceanic conditions that drove it.