Storm surge and overland flooding can be predicted with computational models at high levels of resolution. To improve efficiency in forecasting applications, surge models often use atmospheric forcing from parametric vortex models, which represent the surface pressures and wind fields with a few storm parameters. The future of storm surge prediction could involve real-time coupling of surge and full-physics atmospheric models; thus, their accuracies must be understood in a real hurricane scenario. The authors compare predictions from a parametric vortex model (using forecast tracks from the National Hurricane Center) and a full-physics coupled atmosphere-wave-ocean model during Hurricane Isaac (2012). The predictions are then applied within a tightly coupled, wave and surge modeling system describing the northern Gulf of Mexico and the floodplains of southwest Louisiana. It is shown that, in a hindcast scenario, a parametric vortex model can outperform a data-assimilated wind product, and given reasonable forecast advisories, a parametric vortex model gives reasonable surge forecasts. However, forecasts using a full-physics coupled model outperformed the forecast advisories and improved surge forecasts. Both approaches are valuable for forecasting the coastal impacts associated with tropical cyclones
Sensitivity of Storm Surge Predictions to Atmospheric Forcing during Hurricane Isaac
Storm surge and overland flooding can be predicted with computational models at high levels of resolution. To improve efficiency in forecasting applications, surge models often use atmospheric forcing from parametric vortex models, which represent the surface pressures and wind fields with a few storm parameters. The future of storm surge prediction could involve real-time coupling of surge and full-physics atmospheric models; thus, their accuracies must be understood in a real hurricane scenario. The authors compare predictions from a parametric vortex model (using forecast tracks from the National Hurricane Center) and a full-physics coupled atmosphere-wave-ocean model during Hurricane Isaac (2012). The predictions are then applied within a tightly coupled, wave and surge modeling system describing the northern Gulf of Mexico and the floodplains of southwest Louisiana. It is shown that, in a hindcast scenario, a parametric vortex model can outperform a data-assimilated wind product, and given reasonable forecast advisories, a parametric vortex model gives reasonable surge forecasts. However, forecasts using a full-physics coupled model outperformed the forecast advisories and improved surge forecasts. Both approaches are valuable for forecasting the coastal impacts associated with tropical cyclones
Hurricane Sandy devastated the Northeast US coastline in 2012. In New York City, it caused power outages that affected nearly 2 million people, forced evacuations of 6500 patients from hospitals and nursing homes, prevented 1.1 million children from attending school for a week, and disrupted the daily travel of about 11 million commuters. Many of these impacts were related to flooding of critical infrastructure, including nearly 90,000 buildings, and more than $5 billion in damages in the mass transit system. The maximum observed water level at the tidal gauge located at the southern tip of Manhattan was 5.3 m above the station datum and 2.8 m above the expected tide. This additional water, known as storm surge, was pushed from the open sea by strong winds during the storm. Sandy was one of several recent storms to cause flooding along the US Gulf and Atlantic coasts, including Katrina and Rita (2005), Gustav and Ike (2008), Irene (2011), Isaac (2012), and Hermine and Matthew (2016). Climatic changes are causing these storms to be larger and more intense, last longer, and move farther northward. Their impacts will be more severe to communities in coastal regions in the future.
