Unraveling the Complexity: The Unpredictability of the 2023 Atlantic Hurricane Season
Forecasting the intensity of the upcoming Atlantic hurricane season poses a formidable challenge, owing to a rare confluence of oceanic and climatic conditions that have seldom been observed.
This year, the Atlantic Ocean finds itself in an active storm era, a phase characterized by a sustained period of heightened storm activity. Additionally, sea surface temperatures in the Atlantic are significantly higher than usual, providing ample fuel for storm development, as highlighted by Matthew Rosencrans, the lead hurricane forecaster for the U.S. National Oceanic and Atmospheric Administration (NOAA) during a recent news conference. However, the onset of an El Niño phase within the El Niño-Southern Oscillation ocean and climate pattern is also expected, which typically suppresses the formation of hurricanes.
Rosencrans noted that such a scenario has infrequently occurred in historical records, describing it as a "rare setup" for this year's hurricane season. The NOAA and its researchers reported a 40 percent likelihood of Atlantic hurricane activity being near normal this year. Notably, even this normal activity level is unusually high for an El Niño year. However, there is also a 30 percent chance that the activity will be above normal and another 30 percent chance that it will be below normal.
In its official prediction, the agency anticipates 12 to 17 named storms, with five to nine of them becoming hurricanes, characterized by sustained wind speeds of at least 119 kilometers per hour (74 miles per hour). Among these hurricanes, one to four could reach category 3 or higher, boasting wind speeds of at least 178 kph (111 mph). The Atlantic hurricane season commences on June 1 and concludes on November 30.
The absence of consensus among other prediction groups can be attributed, in part, to the uncertainties surrounding the role of El Niño. On April 13, Colorado State University projected a below-average season with 13 named storms, including six hurricanes. Conversely, on May 26, the U.K. Meteorological Office forecast an extremely active hurricane season in the Atlantic, with 20 named storms, including 11 hurricanes, of which five could reach category 3 or higher. The long-term average from 1991 to 2020 stands at 14 named storms.
Thus far, 23 different groups have submitted their predictions for the 2023 Atlantic season to a platform hosted by the Barcelona Supercomputing Center in Spain. This platform enables users to compare and contrast the various predictions. The predictions show a wide range, spanning from below average to well above average, according to Philip Klotzbach, an atmospheric scientist at Colorado State University responsible for the group's seasonal Atlantic hurricane forecasts.
This divergence in forecasts is primarily due to two major sources of uncertainty, explains Klotzbach. Firstly, the strength and timing of the El Niño's development, and secondly, whether the Atlantic's surface water temperatures will persist above average.
Each group's forecast is based on a compilation of numerous computer simulations of potential oceanic and atmospheric conditions that could emerge during the hurricane season. The agreement among these models determines the probability estimates. However, NOAA's models have encountered challenges in reaching a consensus, prompting Rosencrans to emphasize the high level of uncertainty surrounding this year's outlook.
The emergence of an El Niño phase is signaled by abnormally warm waters in the equatorial Pacific Ocean, leading to shifts in wind strength and humidity across the globe. One way in which El Niño influences the climate is by altering the strength of winds in the upper atmosphere over the northern Atlantic Ocean. These stronger winds can disrupt the formation of storms by shearing off their tops.