Storm Surge Simulations of Hurricane Ike (2008): Its Impact in Louisiana and Texas

Forecast and hindcast simulations were carried out using the ADCIRC storm surge prediction model with two adjacent high-resolution grid domains to assess the impact of Hurricane Ike in Louisiana and Texas. The model was forced by winds generated with an asymmetric parametric wind model that is coupled to the ocean model at every node and every time step. The wind model uses the storm parameters from the National Hurricane Center's best track and forecast advisories to generate the wind and atmospheric pressure fields that drive the storm surge model. A set of 20 forecast advisories combined with best track information, starting 5 days before the predicted landfall, were used to examine the variability in the predicted storm surge resulting from changes in the storm parameters over the course of the advisories. The simulations were grouped into 5-, 4-, 3-, 2-, 1-day ensembles to assess the predictive skill of the forecast and examine the evolution of the forecast convergence. The closer the advisories are to the time of landfall, the lower the range of variability in the surge predictions. The forecasts began to converge with the 2-day ensemble forecast. The RMS error in maximum elevation between each advisory and the best track at each node for each simulation shows that the error decreases substantially over Louisiana and Texas in the last 8 forecast advisories encompassing the last 2 days of the storm. Validations of the hindcast results against NOAA and temporary USGS stations were performed in both Louisiana and Texas to assess absolute model performance.