Tropical activity in the Atlantic Basin is off to a quick start with three named storms already this year. But that’s just one of several strange events we’ve already seen during this Atlantic hurricane season.
Here are four weird things we’ve seen so far this year, one of which happened before the Atlantic hurricane season officially began.
The 2017 Atlantic hurricane season got off to an early start with the formation of Tropical Storm Arlene in the central Atlantic on April 20. Arlene formed from a subtropical depression that developed the previous day.
Arlene’s development was more than a month earlier than the official June 1 start of the hurricane season. Although June 1 marks the season’s start, storms can form before that day as we’ve seen several times in recent years.
Arlene was the first April tropical storm in the Atlantic Basin since Ana in 2003, which also formed on April 20. It was the farthest north a tropical storm has formed in the Atlantic so early in the season.
Tropical Storm Bret’s formation on June 19 was in the so-called main development region (MDR) of the tropical Atlantic. The MDR of the Atlantic typically sees the vast majority of its activity during the height of the hurricane season – August into September.
The southeastern U.S. coast, Gulf of Mexico and the western Caribbean are usual breeding grounds for tropical storms in June. The map below of storm origins since 1950 shows Bret’s far removal from where systems typically develop in June.
Bret is only the third known tropical storm to develop in the MDR region before July 1 in 167 years of records, according to Bob Henson of Weather Underground. Bret’s naming on June 19 also marked the earliest a storm has formed in the MDR, beating Ana, which formed June 22, 1979.
Bret and Cindy roaming the Atlantic Basin as tropical storms at the same time on June 20 was a rare event for the month.
Only three other times have two Atlantic storms existed at the same time during June since records began. The other years were 1909, 1959 and 1968, according to Dr. Phil Klotzbach, tropical meteorologist at Colorado State University.
Last year came close, with Tropical Storm Bonnie fading June 4 and Tropical Storm Colin forming June 5.
The trend in recent years where multiple storms developed in June or earlier continued this year.
We’ve now had three named storms this year, including Arlene, Bret and Cindy. The third named storm of the year doesn’t typically form until around Aug. 14, based on the 1966-2009 average.
Including 2017, five of the last six years have now had multiple storms develop by the end of June. The only year in the past six with no storms by the end of June was 2014.
For perspective, June itself has historically only averaged about one storm every other year. Hurricane season usually becomes more active in August and September.
Here’s a list of all the storms that have developed before June 30 in each season since 2012.