Short-Term Energy Outlook Supplement: The 2007 Outlook for Hurricane Impacts on Gulf of Mexico Crude Oil and Natural Gas Production

摘要

The Atlantic Basin hurricane season officially runs from June 1 through November 30. Wind speed is the primary instrument for classifying the power of a given system. In the United States, hurricanes are categorized on the Saffir-Simpson scale by maximum sustained wind speed: Category 1 (74-95 mph), Category 2 (96-110 mph), Category 3 (111-130 mph), Category 4 (131-155 mph), and Category 5 (156+ mph). Tropical storms are weather systems with a maximum sustained wind between 39 mph and 73 mph. Category 3, 4, and 5 hurricanes are usually referred to as intense or major hurricanes, about 75 percent of which occur during the months of August and September. In addition to the standard classification by tropical storm or hurricane wind-speed category, NOAA also describes the intensity of tropical weather systems using its Accumulated Cyclone Energy (ACE) index, which measures the intensity of the wind within a system and the system's duration. Specifically, it is defined as the sum of the squared maximum sustained wind speeds (in knots) for all 6-hour intervals while the weather system is classified as either a tropical storm or hurricane. The ACE index can be used to describe the intensity of particular storms or to describe the collective intensity of a hurricane season (as the sum of ACE indices for all storms).