Memorable September Hurricanes

 

Hurricane Florence, September 2018  (Source: NOAA)

September is typically the most active month of the Atlantic hurricane season.  Whenever a tropical storm or hurricane is particularly destructive or deadly, the World Meteorological Organization retires its name.  There are four September hurricanes that have impacted the United States during the last 20 years that have had their names retired.

Hurricane Florence (2018): A long lasting Cape Verde hurricane that lasted more than two weeks, Florence was a Category 4 at peak intensity over the open Atlantic.  It had sustained winds of 150 mph and a minimum central air pressure of 937 millibars (mb).  By comparison, standard sea level air pressure is approximately 1013 mb.  Fortunately, it weakened to Category 1 intensity before its landfall in North Carolina on September 14.  However, because the atmospheric steering currents were very weak, it meandered across the Carolinas and Mid-Atlantic Region for several days and caused devastating flooding.  According to NOAA, Florence did an estimated $25.7 billion in damages in the United States (adjusted for inflation to 2021 dollars).

Hurricane Irma (2017): Irma was another long-lasting Cape Verde hurricane that reached Category 5 intensity on two separate occasions.  At peak intensity, Irma had sustained winds of 180 mph and a minimum central air pressure of 914 millibars (mb).  Irma left a deadly trail of destruction across much of the Caribbean and ultimately made landfall in Florida as a Category 4 hurricane.  It was the first Category 4 hurricane to make landfall in Florida since Charley in 2004.  Ultimately, Irma killed dozens in the United States and did $54.5 billion in damages, making it the fifth costliest natural disaster in U.S. history.

Hurricane Ivan (2004): Ivan was the strongest hurricane of a busier-than-average hurricane season.  It was also a Category 5 storm that caused significant damage to Jamaica, the Dominican Republic and the Cayman Islands.  Air pressure is considered a more accurate measure of hurricane intensity than wind speed, and at peak intensity Hurricane Ivan’s lowest air pressure was 910 millibars.  Its highest sustained winds around the center of the storm reached 165 mph.  Fortunately, Ivan weakened to Category 3 intensity before it made landfall in Alabama on September 16.  It caused nearly $29.7 billion in U.S. damages according to the National Hurricane Center.

Isabel (2003):  Hurricane Isabel was the first Category 5 hurricane in the Atlantic Ocean since 1998.  Isabel reached peak intensity on September 11, with maximum sustained winds of 165 mph and a minimum central air pressure of 915 millibars.  Isabel weakened to Category 2 intensity before its landfall in North Carolina on September 18.  Despite weakening, Isabel caused major flooding and damage across much of the Mid-Atlantic Region and northeastern United States.  In the D.C. Metro Region, Isabel caused approximately one million power outages.