2017: A Record-Breaking Hurricane Season

Hurricane Ophelia Over the Eastern Atlantic  (Source: NOAA)

“Ophelia” developed into a hurricane this week in the Atlantic Ocean, a few hundred miles southwest of the Azores.  Hurricanes are relatively rare in that part of the Atlantic.  In fact, Ophelia became an even rarer Category 3 hurricane at 11:00 A.M. with sustained winds of 115 mph and a minimum central air pressure of 960 millibars (mb).  Hurricane Ophelia is “…the farthest east (26.6°W) an Atlantic major hurricane has existed on record,” according to a tweet by Dr. Phil Klotzbach of Colorado State University.  

So far in 2017, there have been 15 tropical storms (sustained winds 39 – 73 mph), of which 10 became hurricanes (sustained winds 74/+ mph), including six major hurricanes.  A “major” hurricane is a Category 3 (111/+ mph sustained winds) or greater on the Saffir-Simpson scale.  While the last Atlantic hurricane season to see 10 hurricanes was relatively recently in 2012, the last time at least six major hurricanes developed in the Atlantic Ocean Basin was in 2005.  

An above average hurricane season had been predicted by NOAA and Colorado State University.  But what made this season unique has been the intensity of some of the hurricanes and their tracks.  There have been two Category 5 hurricanes (Irma, Maria) for only the fourth time since 1960.  To add to that, three Category 4/+ hurricanes made landfall (Harvey, Irma, Maria) in the United States or its territories for the first time on record.  

Hurricane Maria made landfall in Puerto Rico on September 20 as a strong Category 4 storm, with sustained winds of 155 mph and a minimum central air pressure of 917 mb (lower than Hurricanes Andrew or Katrina at their respective times of landfall).  It was Puerto Rico’s strongest hurricane since a Category 5 made landfall in 1928.  While Hurricane Nate was a much weaker storm earlier this month, it became the first hurricane to make landfall on the U.S. Gulf Coast since Isaac in 2012.  It was also the first October hurricane to make landfall on the Gulf Coast since Lili in 2002.

Although the hurricane season continues until the end of November, the second half of October and November tend to see fewer named storms as conditions become less favorable for development.  However, destructive and deadly tropical storms can still develop late in the season.  For instance, Hurricane Wilma made landfall on the west coast of Florida on October 24, 2005, while Hurricane Gordon impacted the United States in November 1994.