2018 breaks record for average Accumulated Cyclone Energy – 2018 also has the most Atlantic subtropical storms in a season

Dr. Jeff Masters
27 October 2018
(Weather Underground) – Subtropical Storm Oscar formed in the waters of the central Atlantic on Friday night, and is expected to stay well out to sea, far from any land areas. Oscar had marginal SSTs to work with on Saturday, near 26.5°C (80°F), but moderate wind shear around 10 knots allowed the subtropical storm intensify, reaching top winds of 60 mph by 11 am Saturday. […]Dr. Phil Klotzbach tweeted:

For the first time on record (since 1970), all Northern Hemisphere tropical cyclone basins (North Atlantic, NW Pacific, NE Pacific, and North Indian) will have above-average seasonal values of Accumulated Cyclone Energy in 2018.

An active 2018 Atlantic hurricane season

Oscar’s formation brings the 2018 tally of activity in the Atlantic to 15 named storms, 7 hurricanes, 2 intense hurricanes, and an Accumulated Cyclone Energy (ACE) index of 121. The 1981 – 2010 averages for the entire season were 12.1 named storms, 6.4 hurricanes, 2.8 intense hurricanes, and an ACE of 105.6. The 15 named storms this year puts 2018 in the upper 15% for the most named storms in an Atlantic season. In records going back to 1851, only 22 out of 168 seasons have had 15 named storms or more (including 2018). The top spots are held by 2005 and 1933, which had 28 and 20 named storms, respectively. However, prior to the satellite era, many short-lived tropical storms that formed far from land missed detection, so it is more relevant to look at stats since the satellite era began in 1970. Since 1970, 14 of 49 seasons have had 15 or more named storms (including 2018), so this year ranks in the top 30% of seasons for total number of named storms since 1970.Oscar is the 7th Atlantic named storm to be classified as subtropical at some point during its lifetime – the most Atlantic subtropical storms in a season on record. The prior record was 5 in 1969, according to Dr. Phil Klotzbach. As explained in our WU backgrounder on subtropical storms, NHC began classifying subtropical storms in 1968, but they did not start assigning them names until 2002. You might think one reason 2018 was able to rack up so many named storms is because each of this year’s subtropical storms got a name. However, all of this year’s subtropical storms were also tropical cyclones at some point over the open ocean. This includes Alberto, which was originally classified as subtropical throughout its track across the Gulf of Mexico. In its final report on Alberto, issued 18 October 2018, NHC concluded that Alberto was actually a tropical storm over the northern Gulf. [more]