Baltimore County News
Captain Lonnie Ledford, Baltimore County Fire Department
Summer in the mid-Atlantic means hot, humid days and cooler nights, and there is always a possibility of thunderstorms. Meteorologists use modern Doppler radar and computer models to track and predict the path of weather events that affect our area. However, without individuals reacting properly to these warnings, many structures are damaged, and individuals are put at unnecessary risk.
How can you prepare for and minimize the potential damages caused by these common weather events? To begin, we have to understand the terminology used by the National Weather Service when they issue notices. The term watch when used in conjunction with a weather event is the less immediately threatening. A watch indicates that the potential for a weather event exists in our area, and preparations should be made; however, the event may not actually occur or it may go around certain areas. Daily activities may continue with a watchful eye on the sky and ear to a radio. A weather event warning, on the other hand, means that conditions are being observed and a weather event is currently happening in the area or is deemed to be imminent within one-half to one hour. Precautions should be taken immediately to secure property and protect yourself and your family. Outdoor activities should be postponed or ceased.
Another term that needs to be understood is the National Weather Service’s use of the word severe. A thunderstorm is classified as severe when it has the potential for wind gusts of 58 mph or when it produces hail one inch in diameter. (A good visual gauge to use is that a US quarter ($0.25) is approximately one inch in diameter.) Hail can damage glass, such as skylights or windows, and it can damage vehicles and hurt or possibly kill animals that are left outside. Bring animals indoors, and place vehicles in garages.
While all severe thunderstorms have the potential for triggering tornados, hail size is good indicator of the potential of formation of tornados. Stronger cyclonic updrafts create larger hail sizes, and this can be indicative of the increased danger of a potential tornado. Lightening, while dangerous, is not included in the National Weather Service’s definition of severe because even less damaging thunderstorms can still produce significant amounts of lightening and lightning strikes.
The United States faces approximately 100,000 thunderstorms per year, and only about ten percent of those are classified as “severe thunderstorms” by the National Weather Service. Severe thunderstorm warnings should be taken seriously, and protective measures should be put into place as soon as possible.
There are several things you can do to prepare for a severe thunderstorm. The first consideration should be finding adequate shelter. Second, there are several life threatening situations that many people do not consider during a severe thunderstorm. The most obvious, and dramatic, is the potential for lightening strikes. Lightning strikes happen in four different ways.
1. Direct strike – the lightening leader comes down and hits the object or person directly. The person or object becomes part of the discharge pathway to the ground. While this type of pathway is not very common, it usually occurs in large open space areas. If caught outside in one of these areas, make yourself as small as possible by crouching down as low as possible, placing your hands on your knees, ducking your head and raising your heels off of the ground. The only parts of your body that should be in contact with the ground are the balls of your feet and your toes. This position offers the best protection when shelter is not immediately available.
2. Side flash or side splash strike – lightning strikes a taller object and jumps to an individual or object nearby, essentially creating a shorter pathway to the ground. Care should be taken to avoid being close to taller objects during a storm. Trees and other tall objects may provide some protection from the rain, but they also are prime targets for lightning strikes, so avoid using them as shelter during a storm.
3. Ground current – lightning strikes a tree or other object and the lightning’s energy is transferred to the ground, where it moves out laterally. If a person or animal is in the area of the lightning strike, they could potentially become a victim of ground current. This type of strike is the most common in the fatalities of livestock and other animals.
4. Conduction – metal objects such as pipes, landline telephone wires and fences are good conductors of electricity. While the metal does not attract the lightning, it provides a superior pathway for its conduction to ground. Try to avoid contact with any metal objects during a storm. Avoid taking showers and using sinks and other plumbing fixtures during a storm, due to its potential to conduct the current if the structure is struck by lightning.
In Let’s Talk About the Weather Part Two, I’ll offer several more storm preparation tips to help keep you and your family safe this storm season.
Revised April 6, 2016