Latest Atlantic Hurricane Trends

 

Hurricane Ida, August 2021  (Source: NOAA)

NOAA just issued its forecast for the upcoming Atlantic hurricane season.  They are expecting another busy season with 14 – 21 tropical storms, 6 to 10 of which will become hurricanes, including 3 – 6 major hurricanes.  That mirrors the Colorado State University forecast that also calls for an above average hurricane season.  An “average” Atlantic hurricane season has 14 tropical storms, of which 7 become hurricanes including 3 major ones. 

Some of the key factors NOAA cites as reasons for expecting another above average hurricane season include the expectation for La Nina conditions to continue.  An episode of La Nina coincides with above average sea surface temperatures in the tropical Atlantic (a requirement for tropical development), along with a below average amount of wind shear (winds that change direction with height in the atmosphere).  NOAA also expects “…an enhanced west African monsoon.”  That can lead to more clusters of thunderstorms that move west off the Central African coastline into the tropical Atlantic where they serve as seeds in tropical storm formation.

The Atlantic has been in a remarkably active cycle dating back to the 1995 season.  For example, the period of 2000 through 2007 saw an average of nearly 16 tropical storms, 8 hurricanes and 3 or 4 major hurricanes.  A “major” hurricane is defined as a Category 3 or higher on the Saffir-Simpson Hurricane Wind Scale with sustained winds of 111/+ mph.  Eight Category 5 hurricanes also developed during this time frame, for an average of one per year.  The most occurred in 2005 with four Category 5 storms: Emily, Katrina, Rita and Wilma.

More recently, the period of 2014 – 2021 saw an average of nearly 17 tropical storms, 8 hurricanes and 4 major hurricanes.  Two Category 5 hurricanes, Irma and Maria, developed in 2017 and the most recent Category 5 Atlantic hurricane was Lorenzo in 2019.  The overall number of named storms isn’t the best indicator of how active a given hurricane season is.  That’s because a season can have an above average number of tropical storms which aren’t intense or long-lasting.  Last season was a good example of this.  Of the 21 Atlantic tropical storms that developed in 2021, 11 lasted three days or less.  

All indications are, however, that 2022 will feature another busier than average Atlantic hurricane season.  Whether or not this season will see any landfalling tropical systems remains to be seen.  That’s why paying attention to the latest forecasts from NOAA and your favorite local meteorologists, such as those on the WUSA9 Weather Team, is so important.  Hurricane season officially gets underway on June 1.