Impact of Hurricane Harvey on the off-shore Currents of Galveston Bay

Buoy current data indicate that anomalous off-shore currents dominated the inner shelf outside of Galveston Bay during and following Hurricane Harvey, a major hurricane that made landfall over the Houston area on August 26, 2017. As the largest precipitation event in the contiguous U.S. on record, Harvey provides a case study to gauge how coastal systems respond to extreme precipitation events. While the general trend on the inner shelf area is for the current to flow at 31.5° east-by-northeast, roughly parallel to the shoreline, the month following Harvey tended to flow 98.96° north-by-northwest, almost perpendicular to the shore. Wind stresses resultant of Harvey's passing to the south incurred strong velocities perpendicular to wind stress as the component of velocity correlated with Ekman flow increased by an order of magnitude during the Hurricane winds. Heavy streamflow from Trinity River then maintained the anomalous current for a total of 47 days (August 25th to October 11th). Similarly, the salinity was reduced by 16.16 PSU and SST was cooled by 4.7 °C within eight days. Analogous effects were not observed in other precipitation events in the 1996-2018 record, even adjusting for scale, further indicating the atypical nature of the hurricane.