The 2021 hurricane season has come to an end for the Atlantic Basin and featured 21 named storms. The Atlantic hurricane season runs from June 1st through November 30th. NOAA’s Climate Prediction Center had predicted this year to be an above-average season, which was accurate. Their prediction on May 20 was that 13 to 20 named storms would develop, six to 10 of those being hurricanes and three to five being major hurricanes.
This season was the third-most active on record in terms of named storms. It marked the sixth consecutive above-normal Atlantic hurricane season and it was the first time on record that two consecutive seasons exhausted the 21-name list. Of the 21 storms that formed this year, eight of them made landfall along the United States coastline; four hurricanes and four tropical storms. One item to note is that five storms this year rapidly intensified, four of which would later become major hurricanes.
Tropical systems break down
Of the 21 named storms this season, there were 14 tropical storms; Ana, Bill, Claudette, Danny, Fred, Julian, Kate, Mindy, Odette, Peter, Rose, Teresa, Wanda, and Victor. For the seventh season in a row a tropical system formed before the official start of the season. This was Tropical Storm Ana on May 22nd. There were a total of seven hurricanes that formed this season with four of those being major hurricanes. We see on average seven hurricanes and three major hurricanes each season.
Hurricane Elsa was the first hurricane, forming on July 1st. It was the earliest fifth-named storm to form on record for the Atlantic Hurricane Season, surpassing the old record by five days. The strongest hurricane to form this year was Sam which was a Category 4 hurricane with maximum winds of 155 mph. The most memorable storm to impact the coastal region of the United States was Ida. Ida rapidly intensified to a Category 4 hurricane in the Gulf of Mexico before making landfall in Louisiana. It is the most destructive and intense tropical system to affect the state since Hurricane Katrina. It also produced catastrophic flooding in the Northeast.
What may have influenced a more active season?
Although this season ended quietly with no systems forming in the month of November, the first half of the season started off active. Matthew Rosencrans, a lead seasonal hurricane forecaster at NOAA’s Climate Prediction Center says “Climate factors, which include La Nina, above-normal sea surface temperatures earlier in the season, and above-average West African Monsoon rainfall were primary contributors for this above-average hurricane season.”
This year isn’t the only active season we have seen in the Atlantic Basin. Some scientists attribute the heightened hurricane activity in recent years to the warm phase of the Atlantic Multidecadal Oscillation that began in 1995. The Atlantic Multidecadal Oscillation, AMO, can best be described as a series of long-duration changes in the sea surface temperatures of the North Atlantic Ocean. The AMO is thought to be driven by a combination of internal climate variability and changes over time in small airborne particles, often referred to as aerosols, over the North Atlantic. However, according to NOAA, the relative contributions of internal variability and aerosols to the observed Atlantic Multidecadal Oscillation remain uncertain.
The 2022 Hurricane Season will begin on June 1st and NOAA’s Climate Prediction Center plans to release their initial season outlook in May.