Hurricane Season Nearing an End

Hurricane Michael, October 2018  (Source: NOAA)

The 2018 Atlantic hurricane season has been a memorable one for being both costly and deadly.  An “average” Atlantic hurricane season features 12 tropical storms, of which six become hurricanes, including three major ones.   Hurricane season began on June 1 and NOAA’s forecast was for a near to slightly busier than average season.  A total of 15 tropical storms, featuring eight hurricanes and two major hurricanes, have formed in the Atlantic Ocean Basin in 2018.  The Atlantic Ocean Basin includes the Atlantic Ocean, Caribbean Sea and Gulf of Mexico.  

The first named storm of the season, “Alberto” developed on May 25 and was initially classified as a “subtropical” storm.  It had characteristics of both a tropical storm that feeds off warm tropical ocean water and a subtropical area of low pressure that also gains energy from a strong temperature gradient.  Eventually, Alberto became a purely tropical storm and made landfall on the U.S. Gulf Coast.  Alberto was the first of six named Atlantic storms this season that spent time as subtropical storms. 

The first major Atlantic hurricane of 2018, Florence, developed near the Cape Verde Islands off the West Coast of Africa.  At peak intensity, it had sustained winds of 140 mph and a minimum central air pressure of 939 millibars.  Fortunately, Hurricane Florence weakened below major hurricane status before making landfall near the North and South Carolina border.  However, Florence was a slow-moving storm that dumped a copious amount of rainfall over much of North and South Carolina, as well as southern Virginia.  The remnants of Florence also brought heavy rainfall to the DC Metro Area on September 17.  

Hurricane Michael developed in early October and was the strongest Atlantic hurricane of 2018.  It was a borderline Category 4/Category 5 storm at peak intensity, with sustained winds of 155 mph and a minimum central air pressure of 919 millibars.  Michael was the first Category 4 hurricane on record to make landfall in the Florida panhandle and caused catastrophic damage in the southeastern United States.  It was still a Category 3 hurricane when it crossed into the state of Georgia, making it the first major hurricane anywhere in the state since 1898.  The names “Florence” and “Michael” are all but certain to be retired by the World Meteorological Organization for being destructive and deadly storms.

There haven’t been any tropical storms or hurricanes in the Atlantic Ocean Basin since Hurricane Oscar lost its tropical characteristic over the colder waters of the North Atlantic Ocean on Halloween.  November is usually a quiet month in the tropics as environmental conditions are generally unfavorable for tropical storm formation.  On the rare occasion a tropical storm or hurricane develops in November, it is usually found in the western Caribbean Sea or Gulf of Mexico.  Hurricane season ends on November 30.