US Hurricane Wind Speed Risk and Uncertainty

This paper presents a summary of updates made to the hurricane simulation model that has formed the basis of the hurricane wind speeds given in ASCE 7 for the period 1998 through 2010. Since the development of the model used for the ASCE 7-98 wind speeds, significantly more hurricane data have become available to improve the modeling process. These new data have resulted in an improved representation of the hurricane wind field, including the modeling of the sea-land transition and the hurricane boundary layer height, a new model for hurricane weakening after landfall, and an improved statistical model for the Holland B parameter. The new hurricane hazard model yields hurricane wind speeds that are lower than those given in ASCE 7-05 even though the overall rate of intense storms (as defined by central pressure) produced by the new model is increased compared to those produced by the hurricane simulation model used to develop the ASCE 7-98 through ASCE 7-05 wind speeds. Estimates of uncertainties in predicted wind speeds are obtained by propagating the uncertainties in key model input variables (such as central pressure) through to the wind speed prediction stage. The two parameters controlling the overall wind speed prediction uncertainty are the modeling Holland B parameter and central pressure. These variables are responsible for similar to 70% of the overall wind speed modeling uncertainty.