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Near-Average Hurricane Season Expected in 2019, NOAA Says
Published: May 23, 2019
The 2019 Atlantic hurricane season is expected to produce a near-average number of hurricanes and tropical storms, according to an outlook released Thursday by NOAA's Climate Prediction Center.
(MORE: Hurricane Central
NOAA expects nine to 15 named storms during the season, including four to eight hurricanes and two to four major hurricanes. This is on par with the outlook released earlier this month from The Weather Company, an IBM Business, which called for 14 named storms and seven hurricanes this season, as well as the Colorado State University outlook released in April, which predicted 13 named storms and five hurricanes.
These three outlooks are near or slightly above the 30-year average of 12 named storms, six hurricanes and three major hurricanes. A major hurricane is one that is Category 3 or stronger on the Saffir-Simpson Hurricane Wind Scale.
Last year, 15 named storms, eight hurricanes and two major hurricanes tore through the Atlantic Basin.
(Note: The Weather Company and Colorado State University forecasts include storms that have already formed.)
NOAA indicated the ongoing El Niño, warmer-than-average sea-surface temperatures in the tropical Atlantic Ocean and Caribbean Sea and an enhanced western African monsoon were three of the factors driving its hurricane season outlook.
El Niño, which is forecast to persist into the heart of the hurricane season, typically suppresses the intensity of the season because of increased wind shear – the change in wind speed with height – in the Atlantic Ocean. Wind shear is detrimental to either the development or maintenance of tropical cyclones.
"Countering El Niño is the expected combination of warmer-than-average sea-surface temperatures in the tropical Atlantic Ocean and Caribbean Sea, and an enhanced west African monsoon, both of which favor increased hurricane activity," NOAA said in a press release.
Though the official Atlantic hurricane season runs from June through November, occasionally we can see storms develop outside those months. We've already seen that this year with Subtropical Storm Andrea earlier this week. This was also the case in the previous two seasons with May 2018's Tropical Storm Alberto and April 2017's Tropical Storm Arlene.
The Weather Company also noted a number of factors contributing to its outlook, including sea-surface temperatures in the Atlantic Ocean, El Niño and other teleconnections, statistical computer forecast model guidance and past hurricane seasons exhibiting similar atmospheric conditions.
Here are some questions and answers about what these outlooks mean.
What Does This Mean for the United States?
There is no strong correlation between the number of storms or hurricanes and United States landfalls in any given season. One or more of the 14 named storms predicted to develop this season could hit the U.S., or none could at all. That's why residents of the coastal United States should prepare each year no matter the forecast.
The 1992 and 1983 hurricane seasons are visceral examples of why you need to be prepared regardless of the seasonal forecast.
The 1992 season produced only six named storms and one subtropical storm. However, one of those named storms was Hurricane Andrew, which devastated South Florida as a Category 5 hurricane.
In 1983, there were only four named storms, but one of them was Alicia. The Category 3 hurricane hit the Houston/Galveston, Texas, area and caused a severe loss of life.
In contrast, the 2010 Atlantic hurricane season was quite active, with 19 named storms and 12 hurricanes. Despite the large number of storms that year, not a single hurricane and only one tropical storm made landfall in the U.S.
In other words, a season can deliver many storms but have little impact, or deliver few storms but with major impacts.
The U.S. averages one-to-two hurricane landfalls each season, according to NOAA's Hurricane Research Division statistics.
The past two hurricane seasons have been particularly destructive.
In 2016, five named storms impacted the southeastern U.S. coast. The most notable of the bunch was Hurricane Matthew, with its powerful scraping of the coast and subsequent inland rainfall flooding.
In the past three seasons, eight hurricanes were so destructive and/or deadly their names were retired from further use by the World Meteorological Organization.
The number of U.S. landfalls had been well below average over the previous 10 years before these seasons.
The 10-year running total of U.S. hurricane landfalls from 2006 through 2015 was seven, according to Alex Lamers, a meteorologist at the National Weather Service. This was a record low for any 10-year period dating to 1850, and considerably lower than the average of 17 per 10-year period dating to 1850, Lamers added.
What's more, none of the U.S. landfalls from 2006 through 2015 involved major hurricanes.
Bottom line: it's impossible to know for certain if a U.S. hurricane strike, or multiple strikes, will occur this season. Keep in mind, however, that even a weak tropical storm hitting the U.S. can cause major impacts, particularly if it moves slowly and produces flooding rainfall.
How Much of a Role Will El Niño Play?
One hurricane season ingredient worth watching is El Niño: the periodic warming of the central and eastern equatorial waters of the Pacific Ocean.
El Niño was ongoing as of mid-May and it's expected to continue through the summer ahead, possibly even into the fall, according to NOAA. This includes the heart of the hurricane season.
"El Niño conditions are expected to persist or, at worst, slowly weaken over the next six months, which should act to help suppress activity a bit," said Dr. Todd Crawford, chief meteorologist at The Weather Company.
If El Niño persists over the next month, The Weather Company may lower the hurricane season outlook's numbers a touch in the next update.
El Niño tends to produce areas of stronger wind shear – the change in wind speed with height – and sinking air in parts of the Atlantic Basin, which are both hostile to either the development or maintenance of tropical cyclones.
With the major exception of Michael, this wind shear was a factor in keeping the Caribbean Sea rather quiet in the 2018 hurricane season, as evidenced by the relative dearth of Caribbean tracks in the 2018 track map above.
But there are several important caveats to this.
Stronger-than-average wind shear was present in the Caribbean Sea in 2018 without an official El Niño. The wind shear suppressed development in the Caribbean but not elsewhere in the Atlantic.
Any Other Factors in Play?
El Niño is only one of several influences on the atmospheric circulation. Water temperatures in the Atlantic Ocean have a much more direct role in tropical cyclone development on the Atlantic side of North America.
Current water temperatures across the North Atlantic Basin show cooler-than-average waters in the far northern and far eastern Atlantic and in various parts of the Gulf of Mexico and Caribbean Sea. Warmer-than-average waters are widespread off the mid-Atlantic and southeastern coasts of the U.S. Water temperatures are generally near average in the eastern tropical Atlantic between the Lesser Antilles and Africa.
Crawford noted that sea-surface temperatures in the Atlantic are currently very similar to those observed during the last three years, which were all active hurricane seasons. However, he cautioned that the North Atlantic sea-surface temperature anomalies in April matched Aprils from previous years that went on to have inactive hurricane seasons.
"On the other hand, there is a large pool of warmer-than-normal sea-surface temperatures off the southeastern U.S. coast, which may again help to favor 'homegrown' systems that develop closer to the U.S., in a similar manner to 2018," said Crawford.
Due to these contrasting factors, Crawford admitted this year's hurricane season outlook is a bit less confident than in previous years.
It isn't the sea-surface temperature anomalies that allow hurricanes to intensify, however. Rather, it's the actual heat of the oceans.
Water temperatures of 80 degrees or higher are generally supportive of tropical storm and hurricane formation and development.
Much of the tropics stay at or above this temperature for most of the year.
So why bring it up if favorable conditions are always around?
If sea-surface temperatures in the main development region (MDR) between Africa and the Caribbean Sea are warmer than average, we often get more than the average number of tropical storms and hurricanes from this region. Conversely, below-average sea-surface temperatures can lead to fewer tropical storms than if waters were warmer.
Warmer waters in the MDR allow tropical waves, the formative engines that can become tropical storms, to get closer to the Caribbean and United States.
Dry air and wind shear are two other factors that can be detrimental to tropical storm or hurricane development.
Americans and the Hurricane Season
The Weather Company surveyed 2,200 adults across the United States and gained some interesting insights about Americans and the hurricane season.
-Americans believe the weather has gotten more severe, but four in 10 have no plans to handle an emergency.
-Only 31 percent of Americans said they would always evacuate if ordered to do so.
-Only 16 percent of Americans have a preparedness kit packed in preparation for a severe weather event.
This article provides a list of tips to help you prepare for a hurricane. Some of them could end up saving your life.
The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.