6.6 Empirical Forecasting of Lightning Cessation at Cape Canaveral Air Force Station and Kennedy Space Center

This research addresses a seldom studied aspect of lightning—lightning cessation. Holle et al. (1992) found that the majority of casualties occur either during thunderstorm initiation or during dissipation. Between these times, when the threat of lightning is obvious, there are fewer casualties. Thus, the initiation and cessation of lightning activity are critically important periods. Florida is particularly at risk from lightning. Florida annually receives more CG lightning than any other state (Fig. 1), earning the title “lightning capital of the United States” (Orville 1994; Hodanish et al. 1997; Orville and Huffines 2001; and Orville et al. 2002). Florida also has the most casualties of any state (Curran et al. 2000). The majority of these casualties occur during the warm season months of May through September, the climatological peak of lightning activity. Florida’s “lightning alley” is located in the central portion of the peninsula (Fig. 1), coinciding with the location of Cape Canavaerl Air Force Station (CCAFS) and Kennedy Space Center (KSC). CCAFS/KSC typically experiences four to ten CG lightning strikes per square kilometer per year (Fig. 2). Considering that CCAFS/KSC employs over 25,000 individuals, many of whom work outdoors, and has over $20 billion of facilities (Boyd et al. 1995), safety concerns require accurate forecasts of both lightning initiation and cessation. While bringing people indoors in a timely matter is important, safety is not fully met unless the advisories are left in effect through the end of lightning activity. Safety is still met if the advisory is left in effect too long, but this detracts from efficiency, impacting CCAFS/KSC both financial and in terms of the launch schedule. This has resulted in the creation of a unique lightning advisory system for the KSC region (Weems et al. 2001; Bott and Eisenhawer 2005). The 45 th Weather Squadron (45WS) issues advisories that alert KSC personnel to the onset of lightning activity and signal when the threat has passed. The 45WS is reasonably satisfied with the accuracy of their lightning initiation advisories. The primary concern is when to discontinue an advisory. Previous reviews of the 45WS’s lightning advisories have revealed that most are maintained too long. However, with an improved understanding of lightning cessation, the 45WS hopes that forecast guidance can be developed to assess with a high degree of confidence, whether a