With the demise of Tropical Storm Sebastien on November 24, we’ve likely seen the end of the 2019 Atlantic hurricane season, with a final tally of 18 named storms, 6 hurricanes, 3 intense hurricanes, and an ACE index of 129.8. The 1981 – 2010 averages for these quantities were 12.1 named storms, 6.4 hurricanes, 2.7 intense hurricanes, and an ACE index of 106, according to data from Colorado State University, so 2019 was near or above average in all metrics.

The season had two ominous harbingers of a warming climate: an ultra-intense hurricane--worthy of a category 6 rating if such a thing existed--and multiple damaging storms that moved very slowly at landfall. The ultra-intense hurricane was Hurricane Dorian, whose 185 mph winds devastated The Bahamas in early September when the mighty category 5 storm stalled over the islands. Dorian and Lorenzo (in far eastern Atlantic) were both category 5 storms, making 2019 the fourth consecutive year in which a category 5 storm developed in the Atlantic basin--a new record.

The damaging slow-moving storms of 2019 were Hurricane Barry (Louisiana, $600 million in damage), Hurricane Dorian (The Bahamas, Southeast U.S. and Canada, at least $4.6 billion in damage), Tropical Storm Imelda (Texas and Louisiana, $2 billion in damage), and Tropical Storm Fernand (northeast Mexico, $250 million in damage). All four storms moved at 8 mph or slower for two or more days near the time of landfall; the average forward speed of a tropical cyclone is about 11 mph.

The Atlantic’s 18 named storms put the 2019 season in pretty rare territory, since only 8 other seasons since 1851 have had 18 or more named storms—mostly recently, in 2012, 2011, and 2010. However, seven of the eighteen Atlantic named storms in 2019 lasted 24 hours or less at tropical storm strength—the most extremely short-lived named storms on record, breaking the old record of 6 set in 2005, according to Colorado State University hurricane scientist Dr. Phil Klotzbach. Four of the seven short-lived storms of 2019 formed in the Gulf of Mexico, which limited their lifetimes due to quick landfalls after formation (Fernand in Mexico and Imelda in Texas) or due to interactions with cold fronts that made them extratropical (Nestor and Olga during October).

After hitting St. Thomas in the U.S. Virgin Islands as a category 1 hurricane on August 28, Hurricane Dorian rapidly intensified into a category 5 hurricane and powered ashore on Great Abaco Island in The Bahamas on September 1, 2019. At landfall, Dorian had sustained winds of 185 mph, gusts up to 220 mph, and a central pressure of 911 mb, tying it with the Labor Day Hurricane of 1935 in the Florida Keys as the most powerful landfalling Atlantic hurricane (by wind speed) on record. Winds of 185 mph would make Dorian worthy of a category 6 rating, if it existed. Dorian was also the strongest hurricane ever recorded in the open Atlantic, outside of the Caribbean and Gulf of Mexico (previous record: Hurricane Irma of 2017, with 180 mph winds). Only one Atlantic hurricane had stronger winds than Dorian: Hurricane Allen of 1980, which peaked with 190 mph winds in the southeastern Gulf of Mexico.

At landfall, Dorian was moving at just 5 mph, and moved at 5 mph or less through The Bahamas for 27 hours at category 5 strength. Dorian tracked only 25 miles in 24 hours—the second shortest straight-line distance tracked by an Atlantic major hurricane in a 24-hour period since 1950. Only Hurricane Betsy in 1965, which tracked 12 miles in a 24-hour period, was slower. Portions of Dorian’s eyewall lashed Great Abaco and Grand Bahama islands with Category 5 winds for a total of 22 hours before the great hurricane finally weakened to Category 4 strength.In records going back over a century, there are no cases where an Atlantic Category 5 hurricane has impacted a land area for as long as Dorian battered The Bahamas. According to the Bahamas Department of Meteorology, Dorian brought a storm tide of 20 to 25 ft (6.1 to 7.6 m), and dropped an estimated 3 ft (0.91 m) of rain over The Bahamas.