Hurricane Season 2021 Nearing a Quiet End

 

Hurricane Ida, August 2021 (Source: WUSA9)

The Atlantic Ocean Basin has seen a busier than average hurricane season for a sixth consecutive year.  There were a total of 21 tropical storms, of which 7 became hurricanes, including 4 major hurricanes.  That’s compared to NOAA’s seasonal average of 14 tropical storms, 7 hurricanes and 4 major hurricanes.  A “major” hurricane has sustained winds of at least 111 mph around the center of circulation, making it a Category 3/+ on the Saffir-Simpson Hurricane Wind Scale.  The Atlantic Ocean Basin includes the Atlantic Ocean, Gulf of Mexico and Caribbean Sea.

“Ana,” the first named storm of 2021 was named on May 22.  That was significant because the hurricane season got underway prior to its official June 1 start for a seventh consecutive year.  The first Atlantic hurricane of 2021, Elsa, developed on July 2.  While it was only a minimal Category 1 storm, it became one of the earliest hurricanes to develop in the eastern Caribbean Sea.  Grace was the first major hurricane of the Atlantic hurricane season less than two months later on August 20.  The Atlantic’s strongest hurricane of 2021 was Hurricane Sam.  At peak intensity, Sam was a high intensity Category 4 storm, just under Category 5 strength, with sustained winds of 155 mph and a minimum central air pressure of 929 millibars (mb).  By comparison, standard sea level air pressure is approximately 1013 mb.

Another Category 4 hurricane, Ida, was easily the most destructive storm of the season.  Ida made landfall in Louisiana on August 29 with sustained winds of 150 mph.  It not only caused widespread devastation along the U.S. Gulf Coast, but also brought flooding rainfall, damaging wind gusts and tornadoes as far north as the Mid-Atlantic Region.  An EF-2 tornado occurred near Annapolis, Maryland on September 1.  The most recent named storm this season was Tropical Storm Wanda that dissipated on November 7.  That ensured 2021 will finish as the third consecutive season with at least one named storm in November.

This season had a total of 21 named storms to date and finished the entire list of names from the World Meteorological Organization.  2021 will finish with one of the highest overall number of Atlantic storms on record, but there are two other metrics that make 2021 less impressive than some other seasons.  No Category 5 Atlantic hurricanes developed this season.  This season will also fall short of the Top 10 most active seasons according to ACE or “Accumulated Cyclone Energy.”  ACE is a function of storm intensity and duration.  Fewer intense and long-lasting hurricanes can generate a higher amount of ACE than a higher number of weaker and/or short-lived tropical systems.  The two most active Atlantic hurricane seasons based on ACE are 1933 and 2005.