Strike Out Lightning Risks
A stronger-than-normal jet stream, as well as a robust wind shear, has DTN/Meteorlogix forecasters predicting an above-average number of severe storms in the spring of 2009. These severe weather events are expected to include large hail, strong winds, and intense lightning, with the greatest areas of the country at risk being the Southern Plains, Southeast, Ohio and Tennessee Valleys, and the Midwest. With an active severe weather season around the corner, public safety officials' severe-weather planning may be an even higher priority this year.
When doing emergency management severe-weather planning, it is common to primarily consider tornados and hurricanes, depending on where you are in the country. But these weather occurrences do not present the greatest weather risk. National Weather Service statistics show that each year, lightning kills more people than tornadoes and hurricanes combined. And for each death caused by lightning, roughly 10 more people are injured. The majority of these lightning injuries leave victims with serious, lifelong neurological damage.
You may wonder, "But what I can do to prevent lightning deaths or injuries? Lightning seems so unpredictable . . . how do I prepare for it? Is there really anything I can do from an emergency management perspective?" Yes, there is much that can be done, both in having plans for how to properly handle lightning dangers and in using tools to detect current lightning and take action. Let's discuss keys to lightning safety for a city's emergency management.
Playing it Safe
Cities have responsibility for a number of activities that pose a particularly high lightning risk. These include swimming pools, park and rec activities, city-operated golf courses, and civic outdoor events. Large open spaces such as ballfields and golf courses increase risk. And civic events with large crowds, such as Fourth of July events or concerts, pose additional challenges.
When lightning occurs -- before lightning strikes your locale, as we'll discuss – people need to be warned and moved to a safe place. Safe places are either indoors in a substantial, electrically grounded structure or in an enclosed vehicle.
The National Weather Service recommends that whenever you hear thunder, get immediately to safety. When lightning is within 6 miles, people should already be to safety. However, here is the difficulty. When you hear thunder, lightning already may be less than 6 miles away and be dangerously close. And, further, it takes time to get people to safety, especially when you're a long distance from a safe place, such as on a golf course, or when you have large crowds to evacuate.
Therefore, you need to know when lightning is approaching before it is 6 miles away. How far in advance you begin evacuation depends on how long it will take you to get people to a safe place. At a Little League game, it could take a minute to get players and fans to their cars. But it could take 10 minutes or more on a golf course or at a county fair.
Make the Right Call, Right Away
So advanced lightning notification is very important. If you wait to hear thunder and see lightning, you are already in danger and do not have time to respond properly. Fortunately, there are tools available today for public safety that can give you advance warning.
Low-cost subscriptions to lightning detection services can give you advance warning of lightning and enable you to keep the public safe. Such services can send alerts when lightning strikes within a user-defined radius around your city. These alerts can be sent to cell phones of key individuals responsible for safety. Actual lightning strikes can be displayed on maps on cell phones, as well. In addition to mobile use, these alerts and displays can be displayed on PCs. Equipping your 911 center or police/fire dispatch with this can be an effective measure.
With such tools, you can receive an advisory alert that lightning is within, say, 30 miles of the city. This is a "heads up" that lightning may be approaching your location and to be on watch status. If lightning strikes within your warning distance -- 8 miles is a commonly used distance -- you'll receive a warning alert to begin evacuation. Having such clear, objective, and simple rules for evacuation is important for successful implementation. And being able to see where lightning is occurring in real time on a map on your cell phone can also be helpful in establishing the credibility of the warning. These advanced but easy-to-use tools are key to modern lightning safety.
Resumption Is Important, Too
In addition to being able to evacuate an area safely in a timely manner, knowing when to resume activity is every bit as important. Investigations have shown that one-third of lightning deaths come from prematurely resuming activity. Advanced lightning detection and notification systems allow you to monitor real-time conditions and receive an alert when lightning risk has passed your warning area. This assists public safety officials in making good decisions on when to resume activity. There can be great pressure to resume play or other activity once it might "look" safe. Effective tools give you the means to ensure the risk has passed and that further thunderstorms are not on their way.
So, to summarize, today's lightning notification systems can give you a simple, low-cost, and effective means to keep the public safe. You can do this with "mobile" decision makers or from a dispatch office, and you can scale your alerting distance to your needs for the varied evacuation times of different locales or events.
Common Misconceptions
Now that I've given you some advice on proactive safety measures for lightning, there are a few misconceptions about lightning you should be aware of:
- You don't have to react until you see lightning or hear thunder. The truth is, at that point you're already in danger. By the time you can see lightning or hear thunder, you should be in a safe place. Safe places are either indoors in a substantial, electrically grounded structure or in an enclosed vehicle. Open shelters or golf carts provide no protection.
- Radar provides an accurate picture of lightning location. Relying on radar is not an adequate guide to tell when lightning is approaching or when it's out of the area. Lightning can strike up to 10 miles away from a thunderstorm, and depending on radar sets you up to make a mistake at both ends of a storm.
- All weather information sources are created equal. Some weather services provide lightning information that is delayed anywhere from 30 minutes to an hour. This is no better than just watching and listening. The typical length of a thunderstorm cell is 20 minutes, so lightning could develop in your area and be done before it even shows up on the delayed Web site. Lightning detection must be in real time, not delayed.
At 54,000 degrees -– six times hotter than the surface of the sun -– and having the ability to strike up to 10 miles outside of a storm, lightning has proven to be one of nature's most deadly forces. Having the right tools and information can help you significantly reduce the risks and liabilities associated with this common and dangerous threat.
Editor's note: This article was written by Don Leick, product management director for DTN/Meteorlogix, with with commentary from DTN/Meteorlogix Chief Science Officer Jeff Johnson.