Severe Thunderstorms

Thunderstorms can be dangerous, despite their small size. Every thunderstorm produces lightning, which kills more people every year than tornadoes. Some thunderstorms can produce hail, strong winds, tornadoes and heavy rain which can lead to flash flooding.

The National Weather Service (NWS) considers a thunderstorm severe if it produces hail at least three-quarters of an inch in diameter, has winds of 58 miles per hour or higher, or produces a tornado.

The greatest threat during any thunderstorm is lightning. Each year in the United States, 75 to 100 people are killed from lightning strikes. Lightning often strikes outside heavy rain and may occur as far as 10 miles away from rainfall. "Heat lightning" is actually lightning from a thunderstorm too far away for the thunder to be heard, however, the storm may be moving in your direction. Light travels faster than sound - meaning lightning flashes can be seen long before the thunder sound. When lightning and thunder closely follow each other, lightning is striking nearby. You can estimate how far away the storm is by counting the number of seconds between a flash of lightning and the next clap of thunder, and dividing by 5.

Strong thunderstorms often produce hail. Hail can be smaller than a pea or as large as a softball, and is dangerous to vehicles, glass surfaces, roofs, plants, crops, and animals. Downbursts and straight-line winds from 100 to 150 miles per hour can occur, which are strong enough to flip cars, vans and semitrucks.

Protect Yourself During Thunderstorms:

• Postpone outdoor activities if thunderstorms are likely.
• If you see or hear a thunderstorm coming, go inside a sturdy building or car. A buidling is the best place to be, but a hard-top vehicle will offer some protection.
  • Rubber-soled shoes and tires offer no protection from lightning.
  • Avoid convertibles - the steel frame of a hard-top provides greater protection from lightning, as long as you're not touching metal.
  • Avoid unprotected gazebos, rain or picnic shelters, golf carts, or baseball dugouts or bleachers.
• If you are outside and you feel your hair stand on end, it means lightning is about to strike. Your hair stands up on end because of the electrical build-up just before lightning strikes.
  • Get to a low, open space as fast as you can. Crouch down on the balls of your feet, place your hands on your knees and lower your head. Make yourself the smallest target possible and minimize contact with the ground. Lying flat on the ground makes you a larger target.
  • Stay away from trees, towers, fences, telephone and power lines.
  • Never stand underneath a single large tree out in the open. Lightning tends to strike the highest point in the area.
• Stay away from metal things like umbrellas, baseball bats, fishing rods, camping equipment, and bicycles. Lightning is attracted to metal and poles or rods.
• Stay away from rivers, lakes and other bodies of water. Likewise, if you are on or in the water, get to land immedately, and move away from the sand on a beach. Water and wet sand are excellent conductors of electricity. When lightning strikes nearby, the electrical charge can travel through the water.
• Stay off the telephone and computer during a thunderstorm.
• Avoid washing your hands or taking a bath or shower during a storm. Electricity from lightning has been known to come inside through plumbing.

If you are Driving During a Thunderstorm and Heavy Rain:

• Pull safely onto the shoulder of the road and stop, making sure you are away from trees and tall objects. Turn on the emergency flashers and wait until visibility is returned.
• Do not drive into standing water, especially during evening hours. You usually cannot determine water depth, or the roadbed may be washed out under the water; rising water levels can stall your vehicle, leaving you stranded.
• Look out for flooding on highway dips, bridges and low areas. It only takes two (2) feet of water to carry away most automobiles.

What to Do if Someone is Struck by Lightning:

• Dial 9-1-1; medical attention is needed as quickly as possible.
• Give first aid. If breathing has stopped, begin rescue breathing. If the heart has stopped beating, begin CPR.
• If the person has a pulse and is breathing, look and care for other possible injuries.
• Check for burns in two places: both where they were struck and where the electricity left their body.
  • Lightning strikes can cause nervous system damage, broken bones and loss of hearing and eyesight.
  • People who have been struck by lightning carry no electrical charge that can shock other people, and can be handled safely.