Aspects of operational forecast model skill during an extreme storm surge event

On 9 November 2007, the east coast of the United Kingdom experienced the worst storm surge for 50 years. It was feared that this event would be as bad as the North Sea storm surge of January 1953 that resulted in over 2000 fatalities in England and the Netherlands. Fortunately, despite minor flooding in East Anglia, surge levels from the Wash to the Thames were approximately 20 cm lower than the worst predictions. This paper analyses the utility and accuracy of the operational flood warnings that were provided. The accuracies of the surge hindcast (using meteorological re-analysis) were better than 10 cm at critical locations. Throughout the storm, the quantification of uncertainty via a prototype ensemble surge prediction system was shown to be valuable. We examine the inundation implied by the most extreme ensemble member, and estimate the flood risk implications had this scenario been realized.