Wednesday, 25 January 2012: 5:00 PM
Lightning Proximity Alerts
Room 335/336 (New Orleans Convention Center )
Management staff of and participants at airports and seaports, outdoor events, and golf courses all care about lightning safety because they all have many people outdoors. They all want to bring people indoors when lightning is imminent and let them resume their activities when it has passed. The most common warning method is the proximity alert: one comes indoors when lightning occurs within some distance, and one goes back out when no lightning has occurred within some distance for some time. In the long run, the proximity alert is dead. Someday approaches that predict storm evolution will deliver better warnings. But the proximity alert is still the most widely used operational lighting alert, and that will remain true for years, particularly for short lead times. So it is worth making proximity alerts better. We examine several years of flashes over the US. For lightning onset, we measure for each distance and lead time the number of unwarned ground strikes and number of annual minutes of warning. For lightning cessation, we measure for each distance, lead time, and flash free duration, the number of unwarned ground strikes and the number of annual minutes of warning. Any operational user of proximity alerts can use these plots to optimize the distance and flash free duration values they use to either increase their safety with no increase in number of minutes indoors, or decrease their number of minutes indoors with no decrease in their safety.