The 2019 hurricane season was remarkable for its dichotomy with most storms either massive powerhouses or weaklings.
The 2019 hurricane season ended above average for the fourth year in a row with an abundance of fleeting systems gone in a blink and one paralyzing horror.
After the decay of Sebastien last week, the final tropical cyclone tally stood at 18 named storms, including six hurricanes and three major hurricanes of Category 3 or higher. That’s compared to an average season of 12 named storms.
It was the first time since 2012’s Hurricane Sandy that a season spawned an “S” storm, and it broke a 2005 record for tropical storms that lived 24 hours or less with seven — a conspicuous landmark some scientists attribute to ever-better technology, allowing forecasters to see the guts of a storm like never before.
“I think it’s pretty remarkable,” said Florida International University associate meteorology professor Haiyan Jiang, about the number of pop-up systems this year. “There were so many storms and 40 percent were short-lived.”
FOUR STORMS THAT MADE LANDFALL
Four storms made landfall in the U.S. during the 2019 season. Barry breached Louisiana’s coast as a Cat 1 hurricane July 13; Tropical Storm Imelda hit near Freeport, Texas on Sept. 17; Nestor made landfall near St. Vincent Island on Florida’s Panhandle as a post-tropical cyclone Oct. 19; and Cat 1 Hurricane Dorian arrived at Cape Hatteras, N.C. on Sept. 6.
But it was Hurricane Dorian’s earlier manifestation that left Florida holding its breath and the northern Bahamas reeling.
IT’S DORIAN WE’LL ALL REMEMBER
Dorian reached Grand Bahama on Sept. 1, making landfall as a Cat 5 storm with 185-mph sustained winds. It would remain nearly stationary through Tuesday. That's an astonishing 36 hours that Dorian raged over Grand Bahama Island nearly unmoving as a Cat 5 or Cat 4 hurricane.
Dorian peak winds were outdone only by 1980’s Hurricane Allen, which had 190-mph winds, and tied with the 1935 Labor Day Hurricane, Gilbert (1988) and Wilma (2005).
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“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,” said Jeff Masters, a meteorologist who writes the Eye of the Storm column for Scientific American. “According to the Bahamas Department of Meteorology, Dorian brought a storm tide of 20 to 25 feet, and dropped an estimated three feet of rain over the Bahamas.”
Dorian’s hurricane winds came within 60 miles of West Palm Beach.
It was the fifth Cat 5 hurricane to form since 2016 — the first time in history that so many Cat 5s occurred in a four-year period — but the 2019 hurricane season wasn’t over yet.
The eye of #HurricaneDorain. You can feel the power of the storm when you stare into its eye from above. Stay safe everyone! pic.twitter.com/yN3MGidY3N— Nick Hague (@AstroHague) September 2, 2019
SPECIFIC CONDITIONS PLAYED A PART IN ACTIVE SEASON
On Sept. 28, a distant Lorenzo exploded to a Cat 5 cyclone about 1,400 miles southwest of the Azores. Lorenzo’s location made history as the farthest east Cat 5 hurricane on record, reaching its pinnacle of intensity around 45 degrees west, according to Colorado State University researcher Phil Klotzbach.
In between the Cat 5s, Hurricane Humberto grew to Cat 3 power far off the mid-Atlantic coast. Hurricane Pablo spun harmlessly in the North Atlantic in late October.
Gerry Bell, lead seasonal forecaster for the National Oceanic and Atmospheric Administration’s Climate Prediction Center, said there were specific conditions present this season that buoyed storm strength — a stronger West African monsoon, warmer Atlantic waters, and weak vertical wind shear across the western Atlantic and Gulf of Mexico.
The storm-killing climate pattern El Nino also abruptly called it quits in August — an unexpected twist in the season. Also, the tropics remained in the storm-inciting warm phase of the Atlantic Multi-Decadal Oscillation.
Bell said the warm phase, which lasts between 25 and 40 years, shows no sign of abating.
“What I find unusual this year is we had two Cat 5s and a bunch of very weak short-lived systems and very little in the middle,” said Falko Judt, a research meteorologist with the National Center for Atmospheric Research. “So we had extremes on either end.”
In addition to the number of named storms, accumulated cyclone energy, or ACE, is an index used to measure tropical cyclones. Ace looks at the longevity and strength of a storm.
This year, ACE was about 125 compared to 106 for an average year. Of the 125, Dorian made up 44 percent of it. Lorenzo accounted for 30 percent.
SHORT-LIVED STORMS: ODDITY OR BETTER SCIENCE?
There still is some debate over whether the high number of short-lived storms was just atmospheric happenstance or advanced science.
Barry held the title of hurricane for just three hours before making landfall in Louisiana on July 13. Pablo was a hurricane for less than 12 hours before succumbing to cold waters northeast of the Azores on Oct. 28.
Imelda was named, and made landfall less than an hour later. Nestor earned tropical storm status Oct. 18, but turned post-tropical less than 24 hours later. Tropical Storm Olga formed Oct. 25, but got caught up by a cold front and went post-tropical six hours later. Tropical Storm Erin maintained its storm status for just 12 hours.
“We are not aware of a formal study indicating that new observing capabilities have affected the number of tropical cyclones,” said National Hurricane Center Deputy Director Ed Rappaport. “However, we do use new technology when it becomes available to us and it has occasionally allowed us to identify the formation or intensification of a tropical cyclone a little earlier than would have otherwise been possible, say, a generation ago.”
But Judt said he believes polar orbiting satellites with scatterometers that can see winds at the surface of the ocean are one reason for the increase. While the technology has been riding on satellites since about 2000, improvements, including those made by the European Organization for the Exploitation of Meteorological Satellites, or EUMETSAT, has led to more and finer observations.
“We are seeing storms that were always there, but we didn’t have the means to detect them,” Judt said.
AccuWeather lead hurricane forecaster Dan Kottlowski agrees that scatterometers have helped identify storms that may not have been named in the past, and adds the new GOES East and Goes West satellites to the list of forecasting improvements.
Images that used to click and send every 15 to 30 minutes are now relayed to forecasters in consistent rapid fire five-minute intervals, or every 30 seconds in cases of severe weather.
“I think in the future we’re going to see a lot more storms spin up and last for 24 hours or less because they are more common than we ever knew,” Kottlowski said. “There are some storms this year that were questionable and if we didn’t have the technology, we probably wouldn’t have named them.”