Storm Surge Probabilities for Hurricane Events

Hurricanes and associated storm surges are costly and devastating natural hazards that affect populations on much of the world's coasts. To help mitigate potential disasters and losses, tools for predicting these hazards are used to indicate areas along the coast that are most vulnerable to storm surge.  However, uncertainty in hurricane tracks and intensity also need to be conveyed to end-users, since this uncertainty affects the interpretation of storm surge predictions.  To help inform our storm surge prediction and awareness efforts (http://nc-cera.renci.org), we are developing a hurricane track generator that extends the method implemented in Davis et al (2010).  In addition to using across track errors, we incorporate along track and intensity errors to compute possible hurricane tracks.  The primary inputs to the track model are a prediction of a hurricane event and the National Hurricane Center’s (NHC) forecast track error database. We use the latter to develop probability distributions for along and across track and intensity errors.   An ensemble of probabilistic tracks is then generated for the hurricane by sampling the error distributions, and each member has a known probability of occurrence.  From this ensemble of tracks, wind fields are computed using a modified Holland (1980) model, and storm surge exceedance probability maps are generated using the storm surge, tide, and wind-wave ADCIRC (Westerink et al, 2008).  We demonstrate the approach using past hurricanes such as Hurricane Isabel (2003). 

Davis, J. R., Paramygin, V. A., Forrest, D., and Sheng, Y. P. (2010). Toward the probabilistic simulation of storm surge and inundation in a limited-resource environment. Mon.  Weather Rev., 138(7):2953–2974.

Holland, G. J. (1980). An analytic model of the wind and pressure profiles in hurricanes. Monthly Weather Review, 108(8):1212–1218.

Westerink, J., Luettich, R., Feyen, J., Atkinson, J., Dawson, C., Roberts, H., Powell, M., Dunion, J., Kubatko, E., and Pourtaheri, H. (2008). A basin- to channel-scale unstructured grid hurricane storm surge model applied to Southern Louisiana. Mon. Weather Rev., 136:833–864.