El Niño: Status and Impacts On The Tropics
Amanda Delaney, Senior Meteorologist
El Niño developed during this past June and is expected to strengthen through at least the end of this year. At this rate, this El Niño could become one of the strongest on record since 1950. In the past month, sea surface temperatures increased on average of 2°C over the Eastern Equatorial Pacific Ocean. El Niño is already impacting the tropics over the Eastern Pacific Ocean and Atlantic Ocean. During El Niño, tropical cyclones usually become more active over the Eastern Pacific Ocean basin and activity diminishes over the Atlantic Ocean. The warmer then normal sea surface temperatures over the Eastern Pacific Ocean and weaker trade winds allow promote more tropical development. A stronger subtropical jet develops over Southern Central America and extends northeast over the Caribbean Sea and the tropical Atlantic Ocean. This subtropical jet is associated with strong upper level winds that will disorganize and tear apart thunderstorms over the tropical Atlantic Ocean. When these storms are disorganized, this does not allow for further organization into a tropical cyclone.
So far the Eastern Pacific Ocean has had above average tropical cyclones develop. By mid-August there have been 9 named tropical cyclones and 3 of these systems were hurricanes. 1 of these hurricanes became a major hurricane. During a typical East Pacific Tropical Cyclone Season, 5 named tropical cyclones have developed and 2-3 hurricane have developed by the end of July. This Atlantic tropical cyclone season is getting off on a slow start as predicted. As of mid-August, only 3 tropical cyclones have developed over the Atlantic Ocean. Although this is not unusual as only 2-3 tropical cyclones typically develop by the end of July over the Atlantic Ocean basin.
In order to show how much El Niño impacts the two ocean basins, let's take a look back at other strong El Niño events which occurred in 1982, 1983, 1997 and 2015. A strong El Niño becomes classified when sea surface temperatures increase up to 1.5°C-2°C or more over the Equatorial Pacific Ocean. Please see the tables below that show the average tropical cyclone numbers and then what tropical cyclones were produced for each year.
As you can see the Atlantic tropical cyclone seasons during El Niño years fell below average while the Eastern Pacific Ocean were above average.
El Niño is expected to continue through the rest of this year and potentially linger through next Spring. Given this, El Niño will likely continue to diminish tropical cyclone development over the Atlantic Ocean while allowing for even more tropical cyclone development over the Eastern Pacific Ocean. Although the tropical cyclone development over the Atlantic will be quieter than normal, this does not mean that we need to drop our guard. As you can see from previous strong El Niño years, that there were still major hurricanes. One prime example is back in 1992 when El Niño ended early that summer. Although tropical cyclone development was below average, one major hurricane developed that year and that was Hurricane Andrew, which significantly damaged parts of southern Florida.
Whether you are traveling in the Atlantic Ocean or Eastern Pacific Ocean, contact WRI regarding the latest tropical developments. You can stay informed through a subscription to our online service, SeaWeather, or request a customized forecast and receive daily summaries of the tropics while using our services.
