Public Information Statement
Issued by NWS Boston, MA

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000 NOUS41 KBOX 021315 PNSBOX CTZ002>004-MAZ002>024-026-RIZ001>008-031315- Public Information Statement National Weather Service Taunton MA 915 AM EDT Tue May 2 2017 ...SEVERE WEATHER PREPAREDNESS WEEK - THUNDERSTORMS AND LIGHTNING... The National Weather Service has declared the week of May 1 to May 5 as Severe Weather Preparedness Week in southern New England. This is the second in a series of five public information statements on various topics related to severe weather awareness. Summertime is a good time for outdoor recreational activities in New England. It is also the time of the year when thunderstorms are most likely. Thunderstorms can be beautiful, but they also can be deadly. While many people think they are aware of the dangers of thunderstorms and lightning, the vast majority are not. There are three basic ingredients needed for the formation of a thunderstorm. They include low level moisture, an unstable atmosphere, and a trigger (a source of lift). Low-level Moisture - This moisture is needed for cloud formation, growth, and the development of precipitation within the cloud. Unstable Atmosphere - An unstable atmosphere allows warm, moist air near the ground to rise rapidly to higher levels in the atmosphere where temperatures are below freezing. An unstable atmosphere also allows air at higher levels in the atmosphere to sink to the ground level rapidly, bringing stronger winds from the higher levels to the ground. A Trigger - Something to set the atmosphere in motion. All three ingredients contribute to the formation of a thunderstorm. In fact, as the magnitudes of these ingredients increase, so do the chances that a thunderstorm could become severe. In the summertime, listen to the latest forecast and learn to recognize the signs which often precede thunderstorm development. Warm muggy air is a sign that ample low-level moisture is available for thunderstorm development. Towering cumulus clouds indicate an atmosphere that is, or is becoming, unstable. The trigger could be continued heating from the sun, an approaching front or sea breeze front, or a cooling of the upper atmosphere. All thunderstorms go through various stages of growth and development. As a thunderstorm cloud continues to grow, snow and ice begin to form in the higher levels of the cloud where temperatures are below freezing, and electrical charges start to build up within the cloud. Negative electrical charges near the middle and base of the cloud cause a positive charge to build up on the ground under and near the thunderstorm. Finally, when the difference between these charges becomes too great, a giant atmospheric spark that we call lightning occurs. Lightning is an underrated killer, usually claiming its victims one at a time. Lightning also leaves many victims with life-long serious injuries. Lightning can strike as far as 10 miles from the side of the thunderstorm cloud. In fact, many lightning victims are struck before the rain arrives or after the rain has ended and the storm is moving away. Most victims also report that at least a portion of the sky was blue when they were struck. While inside a home or building: 1. Avoid any contact with corded phones. 2. Avoid any contact with electrical or electronic equipment or cords that are plugged into the electrical system. 3. Avoid any contact with the plumbing system. Do not wash your hands, do not wash the dishes, do not take a shower, and do not do laundry. 4. Do not stand next to a concrete wall and do not lie on a concrete floor. 5. Stay away from windows, outside doorways, and porches. While outdoors: 1. Plan outside activities so that you minimize the risk of being caught outside in a thunderstorm. 2. If you hear thunder, move inside a safe shelter immediately. Generally, if you can hear the thunder, you are within striking distance of the storm. 3. If the sky looks threatening, move inside immediately. Do not wait for the first stroke of lightning. It could occur anywhere under or near the storm. 4. Stay inside a safe shelter for at least 30 minutes after the last rumble of thunder was heard. Many lightning victims are struck after the worst part of the storm has passed. 5. If you are caught outside in a thunderstorm and cannot reach a safe shelter, you can only minimize your risk of being struck by lightning. If lightning strikes near you, it will most likely strike the tallest object in your immediate vicinity. First, do not be the tallest object in the immediate vicinity and do not be near the tallest object. Second, get as low as possible to the ground, but minimize your contact with the ground. Do not fully lie on the ground. Remember, when it comes to thunderstorm safety, it is your own actions that will determine your personal risk of being killed or seriously injured by the hazards of a thunderstorm. $$ For the latest updates...please visit our webpage at You can follow us on Facebook at You can follow us on Twitter at @NWSBoston is the U.S. government's official web portal to all federal, state and local government web resources and services.