Have you ever heard of a zombie tropical storm? Neither had I until this week but the name aptly fits this year’s hurricane season. On Tuesday, the National Weather Service coined the new name for the revitalization of Hurricane Paulette.  After making landfall in Bermuda as a Category 1 and then strengthening to a Category 2 over the island, the storm was downgraded to a post-tropical low pressure system – typically the end of a tropical storm lifecycle. But the remnants of Paulette held on and intensified to once again become a tropical storm about 300 miles off the coast of the Azores Islands, Portugal.  Although rare, it is not the first time a storm has spun back to life. In 2004 Hurricane Ivan made landfall near Gulf Shores, Alabama, and caused considerable damage and loss of life for the Gulf states. After moving back to the Atlantic and being downgraded to a tropical depression, Ivan again reached tropical storm intensity and moved across Florida and into the Gulf of Mexico, making landfall again over the extreme southwestern tip of Louisiana as a tropical depression.

The 2020 hurricane season has had several rare and “first” events. Last week, a Mediterranean hurricane, better known as a medicane, hit Western Greece. Ianos had sustained winds of 62 mph, bringing heavy rainfall and causing power outages. Medicanes are rare in comparison to the U.S. hurricane season, about one to two times per year, but are expected to increase in number and intensity in the future.

Another rare occurrence this tropical storm season is how common is it for all the names to be used in a single season. It has only happened one other time since the current-day naming system was implemented and that was in 2005. That year, there were 27 different named storms, including Katrina. That season, the National Hurricane Center had to use the Greek alphabet to name six more storms – from Alpha to Zeta, with the final storm spanning the new year into 2006.  What could be a first in this name game is how deep we go into the Greek alphabet.  With 23 named storms in the book and more than two months left in the season, it’s quite possible this season will break the record for most storms. In a typical year, the Atlantic Basin is still in single digit number of storms in September, with an average season seeing about twelve named storms.  

One of the reasons for Paulette “coming back to life” is the same reason for an active tropical storm season—above average sea surface temperatures. Tropical cyclones throughout the world act as giant heat engines, taking the energy from warm ocean waters and transferring the energy into the atmosphere. The warmer the sea surface temperature, the greater the tropical storm heat potential. Typically, sea surface temperatures of greater than 80F allow for tropical cyclone development to occur. Once sea surface temperatures fall below 77F, there is a lack of available energy to maintain intensity and weakening generally occurs. With the warmer sea surface temperatures near Portugal, Paulette was able to regain tropical storm strength.

So, what’s next for this record-breaking hurricane season? It is 2020 so I wouldn’t be surprised if we keep hitting “firsts” for weather events. While it is interesting from a meteorological point of view it is important to remember that these weather events – hurricanes, medicanes and even Zombie tropical storms—have an impact on public safety and business operations. Even states farther inland are being challenged with heavy rainfall and flooding due to these storms. Let’s hope we don’t need to come up with more new names to describe this year’s tropical storm season.