19 Researched and written by Franklyn Michael Supplementary Associate, CARICAD F orecasting for the hurricane season is commonplace today. There are several institutions, agencies and media services that engage in the practice, including the UK Met Office and the European Center for Medium-Range Weather Forecasts, However, the Colorado State University (CSU) in the USA, is regarded as the pioneering institution in hurricane season forecasting. The late Dr. William (Bill) Gray is widely recognised as the pioneer of Atlantic Hurricane season forecasting. He issued the first such forecast in 1984. Dr. Gray continued for 30 years before retiring. This means that the 2024 forecasts are the forty-first. He died in 2016. Dr. Phil Klotzbach replaced Dr. Gray in leading tropical meteorology research at CSU since 2006. The CSU team for the April forecast included Professor Michael Bell, Ph.D., Alex DesRosiers, and Levi Silvers. The Team for the June 11 forecast was listed as: Philip J. Klotzbach, Michael M. Bell, Alexander J. DesRosiers, and Levi Silvers with Special Assistance from Carl J. Schreck III. The CSU began releasing a pre-season or April forecasts in 1995. They usually issue forecasts each year in: April, June, July, August and November. The special hurricane season edition of the CARICAD Horizon newsletter is usually circulated between the June and July forecasts from the CSU. This means that in this edition we are only able to compare the April and June forecasts with the average as we have again done here. The CSU released the pre-season forecast on April 4, 2024. The forecast received widespread media and scientific attention because it called for the most active season ever predicted. It called for 23 named storms, 11 hurricanes and five major hurricanes. It is both notable and memorable that in 2020 there were 30 named storms, 14 hurricanes and seven major hurricanes. The CSU predicts that activity in 2024 will be about 170% of the average season from 1991–2020. In 2023, hurricane activity was about 120% of the average. When you examine the forecast table you will see that the April forecast suggests a remarkably high probability of landfall in the Caribbean. That will be a great concern to all of us if it holds true as a prediction. The unusually high numbers in the April forecast are based on a combination of scientific realities and factors that are intertwined. Foremost among them is the La Niña cycle that we are entering and the exceptionally warm temperatures that have arisen in the Atlantic Ocean. In April 2024, the Atlantic Ocean was already as warm as is normally expected for July. It was 2-5 degrees Fahrenheit above average. Warm ocean water is regarded as the “fuel” for storms. The climatology is complex and involved but the takeaway is that the record shows that in general terms there are more storms in the Atlantic Ocean and the Caribbean Sea in a La Niña cycle than in an El Niño cycle. We are coming out of an El Niño cycle. La Niña conditions are intensifying and the peak of those conditions is expected to coincide with the peak of the hurricane season in August – October 2024. When La Niña conditions follow El Niño conditions, the record shows that storm formation is greater in the Caribbean Sea and the Gulf of Mexico. The record shows that in La Niña years named storms, hurricanes and major hurricanes are all greater than in El Niño years. Additionally, in La Niña years, storms appear more likely to pass through the Caribbean archipelago. Storms will be less likely to curve to the north this year, away from the Caribbean. These are observations based on review of records and data. They are not laws of nature. Strong storms have occurred outside of La Niña years too. TRUNCATED SUMMARY OF THE CSU FORECASTS for 2024 TO DATE • Continues on next page
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