Lightning ground flash density and thunderstorm duration in the continental United States: 1989-96
Additional Document Info
The mean annual flash density, thunderstorm duration, and flash rates were calculated using 121.7 million cloud-to-ground lightning flashes in the continental United States for the period 1989-96. Florida had flash densities over 11 flashes km-2yr-1, while the Midwest, Oklahoma, Texas, and the Gulf Coast had densities greater than 7 flashes km-2yr-1. There was a relative minimum in flash density (three flashes km-2yr-1) in the Appalachian Mountains and Missouri. Thunderstorm duration values exceeded 120 h yr-1in Florida and 105 h yr-1in New Mexico, Arizona, and the Gulf Coast. The maximum annual flash rates exceeded 45 flashes h-1in the Midwest, along the Florida coasts, and along the mid-Atlantic coast with the minimum flash rates, 15 flashes h-1, over the Appalachian and Rocky Mountains. The relationship between thunderstorm duration and flash density is Flash_Density = 0.024(Flash_Hours)1.29producing expected flash densities that are within 30% of the measured densities for over 70% of the nation, with the greatest errors, over 80%, in the intermountain region of the Rockies.