The 2024 Atlantic Hurricane Season is One of the Quietest in Decades, Thanks to a Strong El Niño
We’re now halfway through the Atlantic hurricane season, but it would be totally understandable if you’d barely noticed it’s underway. Since the season kicked off in June, the Atlantic basin has recorded just three named storms, all of which were weak, poorly organized tropical systems. Even through mid-August, only one or two additional tropical storms are expected to form, as the entire season fights against a host of prohibitive environmental conditions.
These unfavorable conditions include this year’s exceptionally strong El Niño, which is poised to go down in the history books as sea surface temperatures skyrocket to unprecedented levels across a critical stretch of the Pacific Ocean. They also include consistent plumes of dry, dust-laden air blowing west off the African coast. Combined, these far-flung atmospheric forces are working overtime to shut down any chance of tropical storms developing across the entire Atlantic basin.
Forecasters currently project this will be one of the quietest Atlantic hurricane seasons in years, with fewer than 10 named storms expected to overcome the poor conditions to form. Experts have been caught off guard by the breakneck speed of El Niño’s intensification through the summer months. This climate pattern, defined by warmer-than-average water temperatures across the equatorial eastern and central Pacific, dramatically reshapes weather systems around the globe.
By definition, El Niño requires water temperatures in this critical equatorial region to sit at least 0.5 degrees Celsius (0.9 degrees Fahrenheit) above the long-term average for several consecutive months. But current measurements show this section of the Pacific is already at least 1.5 degrees Celsius warmer than the seasonal average for this time of year, with some parts of the region recording staggering temperature anomalies as high as 4 degrees Celsius above normal.
These abnormally warm Pacific waters trigger large areas of rising air across the region, which in turn alters upper-atmosphere wind patterns. Increased convective activity over the Pacific, paired with these shifted upper-level wind patterns, combines to push stronger-than-normal winds across the Atlantic basin at upper altitudes — a disruptive effect called wind shear.
Thunderstorms are the foundational building blocks that tropical systems grow from. Strong winds at high altitudes tear apart the structure of forming thunderstorms, ultimately preventing individual storm cells from organizing into a cohesive tropical system.
These same conditions have the opposite effect on tropical cyclone activity across the warm Pacific Ocean. By the start of August, the western Pacific typhoon season was already more active than it has been in almost 50 years. Four separate storms in the region have already reached the intensity equivalent of a Category 5 hurricane, including Sinlaku in April, and Bavi, Dolphin, and Genevieve in July. The central and eastern Pacific are also far more active than usual, with the U.S. National Hurricane Center forecasting above-average cyclone activity in this region through the end of autumn.
But El Niño is not the only factor putting the brakes on this year’s Atlantic hurricane season. The West African monsoon, which typically plays a key role in spawning thunderstorms that drift out over the Atlantic and eventually develop into tropical systems, has been unusually underwhelming this year. Below-average rainfall across areas like Sierra Leone and Guinea confirms that the emerging weather disturbances coming off the continent are weaker than normal.
The Sahara Desert is also further dragging down this hurricane season’s already low potential for development. Frequent intrusions of dry, dust-heavy air blow from east to west across the Atlantic, acting like a lid on the lower atmosphere that squashes almost any chance for new thunderstorms to form.
Add all these factors together, and they’ve created the least active Atlantic hurricane season we’ve seen since at least 2013. Forecasters use a measurement called Accumulated Cyclone Energy (ACE) to rate a season based on both the intensity and lifespan of its storms. An average Atlantic hurricane season generates a total ACE index of 122.5. So far this season, the total ACE index sits at just 3.1 — that’s only 23% of the average ACE for mid-August.
That said, a quieter season does not equal a season with no storms, and El Niño years have a well-documented track record of producing intense, devastating hurricanes even when overall conditions are unfavorable for development. Even with the overall lack of activity, this year’s Tropical Storm Arthur may have already broken Louisiana’s all-time 24-hour rainfall record, with more than 29 inches of rain recorded near the community of Cottonport.
Looking back at past seasons, major destructive hurricanes including Camille, Ivan, Charley, Michael, Idalia, and Lee all developed during years with El Niño conditions in place. That means people living along Atlantic and Gulf coasts should continue to keep up with official forecasts and have emergency preparedness plans in place, just in case a storm develops that threatens land.
