Hurricane Season 2019 Nears an End

Sunset is nearing for the 2019 Atlantic Hurricane Season

The 2019 Atlantic hurricane season concludes this Saturday, November 30.  It has been a busier than average one with 18 tropical storms, six of which became hurricanes including three major hurricanes.  Although hurricane season officially gets underway on June 1, this season got off to an earlier than average start for a fifth consecutive year when “Andrea” developed on May 20.

The strongest hurricane of the season, Hurricane Dorian, reached Category 5 intensity with maximum sustained winds of 185 mph and a minimum central air pressure of 910 millibars.   By comparison, standard sea level air pressure is approximately 1013 millibars.  Typically, the lower the air pressure, the stronger the storm is.  There is sometimes a lag between a fall in air pressure and commensurate rise in the sustained wind speeds of a tropical storm or hurricane.  Fortunately, Dorian had weakened considerably to a minimal Category 1 hurricane when it made landfall in North Carolina on September 6.  

This season’s other Category 5 Atlantic hurricane, Lorenzo, was the Atlantic’s easternmost Category 5 hurricane on record with sustained winds of 160 mph on September 29.  2019 is one of only seven seasons that two or more Category 5 storms developed in the Atlantic Ocean Basin.  Two also developed relatively recently in 2017 (Irma, Maria).  One Category 5 hurricane also developed in the Atlantic in 2016 (Matthew) and 2018 (Michael).  The Atlantic has now had at least one Category 5 hurricane in a record four consecutive years.

Another interesting fact about the 2019 Atlantic hurricane season is the difference between the number of tropical storms that developed, 18, and the number of which intensified into hurricanes, six.  When Tropical Storm Sebastien became a post-tropical storm this week (failing to reach hurricane intensity), 2019 became one of only four seasons since 1966 that a third or fewer of the tropical storms that developed became hurricanes.

The Saffir-Simpson hurricane wind scale ranks hurricanes from 1 to 5.  A minimal Category 1 storm has sustained winds of 74 – 95 mph, while a Category 5 hurricane has sustained winds of 157 mph/+.  A hurricane becomes “major” when it reaches Category 3 status with sustained winds of 111/+ mph.

The 2019 Atlantic hurricane season is also memorable for finishing as a busier than average one despite early expectations for a near average season.  Because a weak episode of El Nino dissipated by July, NOAA revised its seasonal forecast upward in early August.  No additional tropical storms are expected to develop before the season ends on Saturday.  The World Meteorological Organization (WMO) meets during the winter to determine which, if any; names will be retired for being destructive and/or deadly.