Development and Application of Integrated Nowcast-Forecast Operational System (INFOS) for Rip Currents in the Great Lakes

Rip currents are responsible for about hundred drowning fatalities per year in the United States. Approximately 80 percent of rescues in the U.S. are due to people getting caught in rip currents. In the Great Lakes, there were 26 fatalities related to rip currents occurring in southern Lake Michigan alone between 2002 and 2007. Traditional approaches to mitigate rip current hazards are to provide information on escape procedures for beachgoers caught in a rip current. Signage and brochures have been also used as awareness and warning strategies. Life guards on beaches rescue people caught in rip currents. While these methods are all important, the lack of a reliable, consistent, and cost-effective warning system for rip currents remains on the wishful list.

In this talk, development and application of a novel Integrated Nowcast-Forecast Operational System (INFOS) for rip current warning in the Great Lakes will be presented. A mechanistic process-based wave-current interaction hydrodynamic model is developed to resolve fine scale and intermittent rip currents. First a low resolution model for Lake Michigan or Lake Superior is taken and NOAA wind fields are used as input to drive the model. Then the wave and current information around the areas of interest is taken from the coarse grid and applied as boundary conditions for the high resolution model to resolve the rip currents at areas of interest. This two-step process enables to capture rip currents while keeping the computational cost relatively low. For nearshore wave observations, a Wide Angle Imaging Tracking System for Rip Currents (WAITS-RC) is developed to detect rip currents at areas of interest which adds to the consistency and reliability of the system. Both modeling and observations will help rip-current communication and reduce the risk of beach hazards, leading to safer beaches in the Great Lakes.