Optimizing the Lightning Warning Radii at Spaceport Florida

Abstract

Abstract Air Force Manual 91–203 (AFMAN 91–203) directs that a lightning warning be issued when lightning is occurring within a 5 nautical mile (n mi; 1 n mi = 1.852 km) radius of a predetermined location. The 45th Weather Squadron (45 WS), located on the central eastern coast of Florida, provides weather support to Cape Canaveral Air Force Station, NASA Kennedy Space Center, and Patrick Air Force Base. The primary objective of this study is to optimize the lightning warning safety buffer; in particular, to determine if the 5 n mi safety radius can be reduced while maintaining a desired level of safety. The research uses processed Lightning Detection and Ranging II (LDAR-II) data from 2013 to 2016 to map the movement of preexisting lightning storms using ellipses. These ellipses are updated with every lightning flash. The distance from the ellipse boundary of each flash occurring outside the ellipse is recorded. Those exterior flash distances are then used to find the best-fit distribution from which the stand-off distance for the desired level of safety can be calculated. The distances from the edge of the ellipse are fit to a Weibull distribution and a reduction in the radius by 1 to 4 or 5 n mi is selected as the optimized balance between safety and operational impact. The 4 or 5 n mi radii are tested with a resulting failure rate of 3.58%, with an average savings of 130.75 false alarms and 15.7 8-h man days a year for the months of May–September.