LIGHTNING GROUND FLASH DENSITY IN THE CONTIGUOUS UNITED-STATES - 1989

The National Lightining Detection Network, composed of 114 wideband magnetic direction finders for locating cloud-to-ground lightning flashes, was operated with full coverage of the contiguous United States for the first time in 1989. More than 13.4 million flashes were recorded during that year. Ground flash density contours were drawn on a grid with 120 horizontal points and 100 vertical points. This produces a flash density resolution of 50 km in the east-west direction and 30 km in the north-south direction. The peak lightning flash density occurred northeast of Tampa, Florida, with yearly values of 10 km-2. An annual flash density of 8 km-2 was recorded over the Gulf Stream off the Carolina Coast. Local flash density maxima were observed in eastern Texas, Kansas, on the Illinois-Indiana border, and inland along the Carolina Coast extending into Virginia.