4 In order to facilitate easier comparison with other seasonal forecasting groups (e.g., NOAA, Tropical Storm Risk, etc.), we have decided to start predicting an Accumulated Cyclone Energy (ACE) index as part of our seasonal forecasts. ACE is defined to be a measure of a named storm’s potential for wind and storm surge destruction defined as the sum of the square of a named storm’s maximum wind speed (in 104 knots2) for each 6-hour period of its existence. ACE is similar to the Hurricane Destruction Potential (HDP) index that we forecast for a number of years.