Late-Season Tropical Storm Sebastien Develops Off Caribbean's Leeward Islands

The 19th named storm of the 2019 hurricane season, Tropical Storm Sebastien, formed in the Atlantic on Tuesday at 11 a.m. The National Hurricane Center (NHC) forecasts that "some slight strengthening is possible over the next day or so."

Sebastien's winds over the Atlantic have reached 45 mph. The NHC, a division of the National Weather Service, noted that "tropical-storm-force winds extend outward up to 105 miles from the center."

The NHC also said an oncoming cold front may overtake Sebastien in the coming days. Sebastien is almost 300 miles northeast of the Leeward Islands in the Caribbean. According to the Weather Channel, the cyclone will veer off into the Atlantic and not hit land.

Sebastien had been monitored earlier. "A disturbance over the central Atlantic has a medium chance of developing into a tropical or subtropical cyclone during the next couple of days while it moves northwestward and then northward over the open Atlantic," a tweet from the NHC said on Monday. An earlier tweet indicated that the NHC was monitoring the storm's development starting on Sunday.

hurricane barry
A flooded plain in Abbeville as Tropical Storm Barry makes landfall in Louisiana on July 13. Seth Herald/AFP/Getty

The NHC pointed out that there is little room for greater intensity because of the dry air and changing wind speeds surrounding the storm. Still, some surrounding low pressure may cause the storm to strengthen a bit.

Nonetheless, once the storm begins to interact with a nearby cold front, it should be absorbed by the front within two days. There are some timing variations among the models on when the cyclone will become absorbed by the front, and it is possible that the storm could be absorbed sooner than indicated, the NHC noted.

Sebastien is expected to remain at sea throughout its entire cycle. "The model guidance is in good agreement on this scenario, and on the official forecast track the cyclone will remain over open waters for the duration of its existence," the NHC said.

While the Weather Channel predicts that this storm may not affect those on land, it does warn that hurricane season does not end until November 30. It also noted that developments at this point in the season are not a cause for alarm. The NHC has not issued any coastal watches or warnings.

Late-season storms are fairly common, and while often benign, they can occasionally cause destruction. For example, 2016's Hurricane Otto, a Category 3 storm, left 23 dead after hitting Panama, Costa Rica, Nicaragua and Colombia.

While Otto was probably the most destructive late-season storm in recent memory, a few major storms have hit Central America and the Caribbean in the past five years, including Hurricane Kate in 2015 and Tropical Storm Rina in 2017. Both struck in early November. While Rina hit Central America, Kate is noteworthy because it extended from the Bahamas to parts of Ireland and the U.K., causing high winds and flooding.

According to the National Weather Service, hurricanes and tropical storms can occur at any point in the year, but in the past decade seven named storms have formed in May, before the season's official June 1 start date.

The Center for Climate and Energy Solutions reported that there has been an increase in the average number of tropical storms and hurricanes from 2000 to 2013. Meanwhile, the National Oceanic and Atmospheric Administration has said that global warming will also cause higher rainfall rates, more intense cyclones and a tendency for more storms to reach Categories 4 and 5.

While Sebastien will likely not affect U.S. or Caribbean citizens, there have been some reports of late-season hurricanes causing enormous amounts of damage. One of the worst occurred in Cuba back in 1932, with over 3,000 deaths from the hurricane.