Influence of Major Hurricanes “Helene” and “Milton” in 2024 on EVA of the Long Ocean Water Level Record at Key West, USA

This paper investigates the influence of back-to-back major hurricanes “Helene” and “Milton” which devastated south-eastern regions of the USA in 2024, and the extent to which associated storm surges influenced Extreme Value Analysis (EVA) of the long ocean water level record at Key West, Florida dating back to 1913. The highest recorded storm surge of 890 mm was recorded during a major hurricane event in October 1944, approximately 56 mm higher than the peak of the surge recorded at Key West during hurricane “Wilma” in 2005. Reanalysis of 2023 published EVA results for Key West indicate that despite the devastation of “Helene” and “Milton”, the super-elevation of the ocean water surface above Mean Sea Level (MSL) recorded at the Key West tidal facility during these hurricanes were at or below that which would be expected around once per annum. The timing and location of the peak of the storm surge with high predicted tides is no more than coincidental but remain the governing factors behind realizing record-breaking water levels over the historical record.