2021 joins the previous 5 Atlantic hurricane seasons by climbing above the seasonal average in Accumulated Cyclone Energy. Climatological average Accumulated Cyclone Energy (averaged 1981-2010) is 105.6, but 2021 has already eclipsed 117, meaning if the rest of the year was magically quiet, it still would have been an above average year.
Accumulated Cyclone Energy, or A.C.E., is a measure of the amount of total energy released by storms during a hurricane season. A.C.E. takes into account storm strength, as well as the amount of time the storm lasted and how long the storm was at peak intensity. Storms like Hurricane Larry and Hurricane Sam have added a tremendous amount of A.C.E. to the 2021 season, even more than Hurricane Ida, because they became quite strong, and maintained a strong intensity over a long period of time.
Hurricane Sam is still ongoing, and looks to really rack up the A.C.E. this week, as it’s forecast to remain a major hurricane (cat. 3 or greater) through at least Saturday morning, and remains a hurricane into next week!
While Larry and Sam didn’t and won’t have major impacts on land, they produced a ton of energy during their lifespan. This season’s most memorable storm so far has almost certainly been Hurricane Ida though. While Ida only produced the third most A.C.E. this year, it made landfall as a major hurricane in Louisiana, making it the most impactful storm in the Atlantic hurricane season so far. Of course, the season isn’t over. While we’re on the downhill side of the 2021 hurricane season, we’ve still had impactful storms this late in the year.
In recent memory, Hurricane Michael (2018) and Zeta (2020) were storms that formed and made landfall in October. We’ll continue to vigilantly monitor storms as they develop through the rest of the season.