It's difficult to predict how active the Atlantic hurricane season will be this year due to a rarely seen confluence of oceanic and climatic factors.
Why the 2023 Atlantic hurricane season is especially hard to predict
The Atlantic Ocean is currently experiencing an active storm era, a period of years-long increasing storm activity. Additionally, this year's sea surface temperatures there are substantially higher than typical, which can intensify storms, according to Matthew Rosencrans, the senior hurricane forecaster for the U.S. National Oceanic and Atmospheric Administration. However, the El Nio-Southern Oscillation ocean and climate pattern, which tends to inhibit storm generation, will also enter an El Nio phase this year.
In total, the organisation expects 12 to 17 named storms, of which five to nine are expected to intensify into hurricanes and have sustained winds of at least 119 km/h (74 mph). There might be one to four category three or higher storms among them, each with winds of at least 178 kph (111 mph). The official start of the Atlantic hurricane season is June 1 and it lasts until November 30.
Predictions from other groups are not unanimous, in part because it is unclear what role El Nio will play. Colorado State University in Fort Collins announced on April 13 that it expected the season to be below average, with only 13 named storms, including six hurricanes. The U.K. Meteorological Office forecast an extraordinarily active hurricane season in the Atlantic on May 26, predicting 20 named storms, 11 hurricanes, and up to five category 3 or higher storms. Between 1991 and 2020, there will be 14 named storms on average.
A portal run by the Barcelona Supercomputing Centre in Spain is currently hosting estimates for the 2023 Atlantic season from 23 different groups, allowing users to compare and evaluate the various predictions. The wide range of these estimates, "from below average to well above average," is noted by Colorado State University atmospheric scientist Philip Klotzbach, who is in charge of the group's seasonal forecasts for Atlantic hurricanes.
The strength of the El Nio and the time of year it is predicted to occur are two major areas of uncertainty, according to Klotzbach, as are whether the Atlantic's surface water temperatures will continue to be above average.
The predictions made by each organisation are based on a compilation of numerous computer simulations of potential ocean and atmospheric conditions during the hurricane season. A probability estimate is generated by how frequently those models concur. The inability of NOAA's models to concur was cited by Rosencrans as the reason why probabilities were not 60 to 70 percent. That illustrates the fact that the picture for this year is rather unpredictable.
Unusually warm waters in the Pacific Ocean's equatorial region are a harbinger of an upcoming El Nio phase, which is linked to global changes in wind speed and humidity. El Nio modifies the strength of winds in the high atmosphere over the northern Atlantic Ocean, which is one way it affects the climate. Stronger winds have the potential to shear off the tops of developing storms, impeding the development of hurricanes. On the other side, hurricanes are fueled by hurricanes by giving energy to storm systems in warmer ocean waters like those in the Atlantic at this time. Which of those two forces will win out determines how lively the season will be.
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For instance, the Met Office stated that its climate simulations indicate that this year's El Nio would result in very modest wind shear, while surface water temperatures will continue to be significantly higher than average. Similar abnormally warm waters were discovered to be the main reason for the abundance of strong Atlantic hurricanes in 2017 (SN: 9/28/18).
Forecasts for hurricanes may grow progressively less certain in the future. It is unclear how global ocean and climate patterns like the El Nio-Southern Oscillation will change as a result of climate change (SN: 8/21/19). According to computer simulations, these global-scale "teleconnections" may become a little more dispersed as the atmosphere warms, which could make them more unpredictable (SN: 2/13/23). Ocean temperatures are anticipated to rise as a result of climate change.
On the other hand, Super Typhoon Mawar, a potent storm that tore through Guam as a category 4 cyclone before barreling towards the Philippines on May 25 and building to a category 5, signalled the start of the Pacific Ocean's hurricane season.
