The 2020 Atlantic hurricane season is forecast to be unusually active, according to a seasonal outlook from the National Oceanic and Atmospheric Administration (NOAA). Any landfalling storms could create unprecedented challenges for government officials working to respond to the coronavirus pandemic, which scientists expect to continue, albeit possibly at a slower pace, throughout the summer.
The NOAA outlook calls for a 60 percent likelihood of an above-average season, with a 70 percent chance of 13 to 19 named storms, six to 10 of which will become hurricanes. Three to six of those could become major hurricanes of Category 3 intensity or higher, and there is a chance that the season will become “extremely active,” the agency said.
NOAA’s outlook shows only a 10 percent chance of a below-average Atlantic hurricane season.
An average season produces 12 named storms and six hurricanes, three of which intensify into major hurricanes.
“We’re not seeing anything that would indicate a likelihood for a below-average season,” said Gerry Bell, lead hurricane season forecaster with NOAA’s Climate Prediction Center.
The agency is basing this outlook on several factors, including an above-average West African monsoon season, below-average wind shear across the Atlantic, and an absence of an El Niño event in the tropical Pacific Ocean that can stifle Atlantic hurricane activity. Much of the North Atlantic Ocean and Caribbean Sea currently has unusually mild sea surface temperatures for this time of year, including record warm waters in the Gulf of Mexico. Hurricanes get their energy by siphoning moisture and energy from warm ocean waters.
Recent projections of conditions in the tropical Pacific, which can influence the Atlantic Ocean basin as well, call for increased odds of a La Niña event developing toward the end of summer and early fall.
Such events are characterized by cooler-than-average sea surface temperatures in the equatorial tropical Pacific, and they can lower wind shear over the tropical Atlantic. This makes conditions more favorable for tropical cyclones to form and maintain their strength, since wind shear — winds varying in speed and/or direction with height — can disrupt such storms.
The new NOAA outlook comes after a slew of private sector hurricane outlooks also have predicted an above-average season.
Forecasters at Colorado State University released an outlook in April calling for a total of eight hurricanes to form in the Atlantic, which is above the seasonal average of 6.4 such storms. Of those, four were predicted to become major hurricanes, above the average of 2.7. Significantly, that outlook placed nearly 70 percent odds that least one major hurricane — reaching Category 3 strength or greater with winds exceeding 111 mph — would make landfall in the Lower 48 states.
The Colorado State team forecast a total of 16 named storms anticipated to form in the Atlantic Basin overall, including tropical storms. That’s above the average of 12 named storms.
AccuWeather, based in State College, Pa., is also predicting an above-average season, with 14 to 18 named storms. Another seasonal forecast, out of Penn State University, is predicting one of the most active Atlantic tropical seasons on record.
The higher-end storms, of Category 3 and greater, are responsible for the most damage, and climate change research, including a study published on Monday, has found an increased likelihood of major tropical cyclones as the world warms. Each of the past four Atlantic hurricane seasons has featured at least one Category 5 storm.
Other studies have shown that storms may be approaching and moving over land more slowly, which worsens their impacts, and there is robust scientific agreement that they are producing more rainfall as ocean and air temperatures increase. Hurricane Harvey, for example, which struck Texas in 2018, led to an all-time rainfall record for any landfalling tropical system in the United States.
Significantly, the Colorado State forecasters said they anticipate an “above average probability for major hurricanes making landfall along the continental United States.”
The Atlantic hurricane season officially begins June 1, peaks in September and ends Nov. 30. However, the 2020 season has already started, since Tropical Storm Arthur formed in May.
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