Possible Effects of the Loop Current on Intensity and Rapid Intensification of Hurricanes in the Gulf of Mexico



Young, Sherry L

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Increasing population in coastal communities is putting more lives and property at risk from hurricanes. A great need exists for a better understanding of hurricane intensity and rapid intensification; especially if frequency and intensity could increase because of warming oceans. Eleven Gulf of Mexico hurricanes and their fluctuations in intensity relative to proximity to the Loop Current, ocean heat content, depth to the 26°C isotherm, and SST were investigated. ESRI ArcMap was utilized to map and relate hurricane and ocean surface layer data obtained by satellite, reanalysis products, and National Hurricane Center observations. 164 data points were binned to sort by proximity to the Loop Current and to isolate other factors such as eyewall replacement cycles and wind shear. Linear regression was used to calculate correlations between variables and intensity, percent of maximum potential intensity, and to calculate probability of rapid intensification. Katrina had the best correlation between sustained wind speed and ocean heat content at 91% during rapid intensification episodes. During favorable conditions, data points with the highest sustained wind speeds of 250 km/hr or more and that reached 100% of maximum potential intensity occurred where sea surface temperature was 29.75°C or greater, depth to the 26°C isotherm was 50 m or more, and tropical cyclone heat potential was 90 kJ/cm² or more. Hurricanes over the Loop Current had a greater probability of intensifying at 39% and undergoing rapid intensification at 26.5%, compared to those over Gulf common water where ~25% intensified and ~17% rapidly intensified, and had less of a probability of de-intensifying during both favorable and unfavorable conditions. During favorable conditions, hurricanes over the Loop Current intensified ~62% and rapidly intensified ~57% of the time while those over Gulf common water intensified ~48% and rapidly intensified ~40% of the time. Results suggest that increased ocean heat content and depth to the 26°C isotherm in the Loop Current limits surface cooling due to mixing permitting additional intensification during favorable conditions.



Hurricanes, Katrina, Rita, Dennis, Lili, Gulf of Mexico, Loop Current, Rapid intensification, Tropical cyclones