Early Season Hurricanes

"Arthur" approaching North Carolina on July 3, 2014  (Source: NASA)

Although a tropical storm forms on average every other June in the Atlantic Ocean, a hurricane so early in the season is much more unusual.  A hurricane develops in June on average only once every five years according to data from NOAA. 

So far in 2015, there have been two named storms.  Tropical Storm Ana formed before the season began (on June 1) and made landfall in South Carolina on May 10.  Tropical Storm Bill developed on June 15 and made landfall in Texas on June 16.  However, there hasn’t been a hurricane during the month of June in the Atlantic Ocean Basin (that also includes the Gulf of Mexico and Caribbean Sea) since 2012.  That’s when Chris became a minimal hurricane and brought Bermuda some appreciable rainfall.  Ironically, 2012 was the last busier than average hurricane season in the Atlantic Ocean.

There was also a rare June hurricane in 2010, when Alex became a Category 2 storm with sustained winds of 110 mph in the western Gulf of Mexico.  It made landfall in northeastern Mexico with some of its effects being felt across southern Texas.  A system gets a name when sustained winds reach tropical storm strength around the center of 39 mph.

Once maximum sustained winds reach 74 mph (as they did in Alex on June 29, 2010) the system becomes a hurricane. Conditions were ideal for Alex to intensify with exceptionally warm ocean water – well above the 80 degree threshold.  The pressure in Hurricane Alex dropped to a relatively low level of 946 millibars – more characteristic of a borderline Category 3/Category 4 storm on the Saffir-Simpson Hurricane Scale.  Alex was the first June hurricane to form anywhere in the Atlantic Ocean Basin since 1995.

Sometimes the first hurricanes don’t form until much later in the season.  In 1992, the first named storm of the season also became the season’s first hurricane.  Andrew formed in mid-August and remains one of the costliest natural disasters on record and only the third Category 5 hurricane to make landfall in the United States.  More recently, in August 2011, Hurricane Irene became the first hurricane of the season on August 22.

It was at this point last season that meteorologists at the National Hurricane Center and holiday beachgoers were tracking Hurricane Arthur.  It was the first named storm of the 2014 season and developed into a hurricane on July 3.  Arthur became a Category 2 hurricane with sustained winds of 100 mph and gave eastern North Carolina a glancing blow.  Unlike last July, no tropical storms or hurricanes are expected anywhere in the tropical Atlantic Ocean this July 4^th holiday weekend.