Diagrams showing the model fields used in the study.
Model fields for sea surface temperature (SST) and currents prior to hurricane intensification at landfall for three 2020 Atlantic hurricanes: Sally (top panels), Hanna (mid-panels) and Eta (bottom-panels). The left panels show SST (shading), instantaneous ocean surface currents (black arrows) and the 150 meters isobaths (dashed contours). The red lines show the sections that will be profiled in the middle column, magenta in the right column. The middle panels show cross-section of SST (shading) and along track currents (black arrows) on regions of coastal downwelling. The right panels show similar cross-sections but on the regions of the storms’ cold wake, with the red lines marking the 300 meters cutoff depth in the middle panels. White contours in the middle and right panels are shown every 2K, with the 26 degrees celsius isotherm highlighted in black. Credit: Gramer et al. [2022], Figure 2
Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: Geophysical Research Letters

Forecasting the intensity of landfalling hurricanes can be difficult when the storms’ intensity changes just before landfall. Using a coupled model and buoy observations, Gramer et al. [2022] analyzed three 2020 landfalling Atlantic hurricanes (Sally, Hannah, and Eta) that intensified as they approached the coast. They showed that the hurricane winds blowing parallel to the coast caused the water levels to rise near the coast leading to coastal downwelling. This process brought warm surface water over the continental shelf, which further intensified the landfalling hurricanes. This is an important result, as it has a direct impact on forecasts of the hurricane intensity at landfall and should be incorporated in future versions of hurricane forecast models.

Citation: Gramer, L. J., Zhang, J. A., Alaka, G., Hazelton, A., & Gopalakrishnan, S. (2022). Coastal downwelling intensifies landfalling hurricanes. Geophysical Research Letters, 49, e2021GL096630. https://doi.org/10.1029/2021GL096630

—Suzana Camargo, Editor, Geophysical Research Letters

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