Thunderstorms

Thunderstorm
Thunderstorms are most likely to occur in the spring and summer during the afternoon and evening, but they do occur year-round and at all hours.

Key Terms Used by the NWS
The National Weather Service (NWS) is responsible for issuing alert information to the public over the emergency broadcasting radio and TV stations. Here are the key terms that they use in their broadcasts when describing severe thunderstorms:
  • Severe Thunderstorm Watch - Conditions are favorable for the development of a severe thunderstorm in particular areas.
  • Severe Thunderstorm Warning - Conditions have been reported by spotters or detected by radar that represent imminent danger to life and property of those in the path of the storm.
Take Protective Actions
Despite their relatively small size (the average storm is 15 miles in diameter and 30 minutes in duration), all thunderstorms are dangerous, producing heavy rain, strong winds, and lightning. New Castle County experiences an average of 2,150 lightning strikes per year. The air near an average lightning strike is heated to 50,000º F. The rapid heating and cooling of the air causes a shockwave that results in thunder. If you can hear the thunder, you are close enough to be struck by lightning and you need to implement the following protective actions for you and your family members immediately.

Protective Actions When Home
  • Stay inside and away from windows.
  • Unplug electrical appliances, entertainment devices, and lead cables / wires.
  • Do not use water faucets, bathtub, shower, hot tub, or other items connected to your water system.
  • Do not use telephones, except for emergency calls (cell or cordless phone is a safer choice than a corded phone, but distance yourself from its power base).
  • Practice the 30-minute rule - wait at least 30 minutes after last seeing lightning or hearing thunder before going outside or resuming normal activities. "When thunder roars, stay indoors."
Protective Actions When Outside
  • Seek a substantial, enclosed building or metal-topped vehicle with windows up, engine off, and radio off.
  • If shelter is not available, find a low spot in an area away from natural lightning rods and metal objects such as tall trees, fences, poles, water, hill tops, recreational and farm equipment, motorcycles, golf carts, golf clubs, bicycles, baseball hats, and guard rails.
  • Position yourself to be the smallest and lowest object in the area by squatting low to the ground on the balls of your feet and placing your hands on your knees with your head between them.
  • Practice the 30-minute rule - wait at least 30 minutes after last seeing lightning or hearing thunder before going outside or resuming normal activities. "When thunder roars, stay indoors."