Severe Thunderstorms, Tornadoes, and Hail

A thunderstorm impacts a relatively small area when compared to a hurricane or a winter storm. A typical thunderstorm lasts an average of 30 minutes. Despite their size, ALL thunderstorms are dangerous. Of the estimated 100,000 thunderstorms that occur each year in the United States, about 10 percent are classified as severe (winds of 58 miles per hour or greater and/or hail that is one-inch wide or greater). Thunderstorms can feature damaging winds, lightning, hail, flooding, and an occasional tornado.  

Hail, lightning, and tornadoes are explained on this page, while flooding is described on the following tab as it can also be caused by a tropical storm or hurricane.


What do you need to know about lightning? Follow the motto "when thunder roars, go indoors."
  • There is NO safe place OUTDOORS when a thunderstorm is nearby. Almost all fatalities related to lightning happen during outdoor activities such as swimming, camping, fishing, golfing, etc.
  • The energy from one lightning flash could light a 100-watt light bulb for more than three months.
  • Rubber-soled shoes and rubber tires provide NO protection from lightning. The steel frame of a hard-topped vehicle provides increased protection if you are not touching metal.
  • Lightning-strike victims carry no electrical charge and should be helped immediately. Call 9-1-1 and begin CPR immediately if the person has stopped breathing. 
How can you avoid the lightning threat?
  • Have a lightning safety plan. Know where you’ll go for safety and how much time it will take to get there. If on a boat, pay attention to an approaching storm and take action.
  • Postpone activities. Before going outdoors, check the forecast and postpone activities to avoid being caught in a dangerous situation.
  • Get to a safe place. If you hear thunder, even a distant rumble, immediately move to a safe place. Fully enclosed buildings with wiring and plumbing provide the best protection. Sheds, picnic shelters, tents, or covered porches do not protect you from lightning. If a sturdy building is not nearby, get into a hard-topped vehicle and close all the windows.
  • If you hear thunder, don’t use a corded phone. Cordless phones, cell phones, and other wireless handheld devices are safe to use.
  • Keep away from electrical equipment, wiring, and water pipes. Sensitive electronics should be unplugged well in advance of thunderstorms. Don’t take a bath, shower, or use other plumbing during a thunderstorm. 


What do you need to know about hail?
  • Strong updrafts within a thunderstorm carry water droplets to a height where they freeze. Ice particles grow in size, becoming too heavy to be supported by the updraft, and fall to the ground as hail.
  • Hail is larger than sleet; it can be larger than a softball (5 inches wide).
  • Large hailstones can fall at speeds faster than 100 mph.
  • Hail causes more than $1 billion in crop and property damage each year in U.S.
  • Harford County has a long history of hail-producing thunderstorms.


In an average year, 1,200 tornadoes cause 60 to 65 fatalities and 1,500 injuries nationwide. Approximately 10 tornadoes have been recorded in Harford County in the past 10 years. Warm, humid, and windy weather is ideal for tornadoes; they can occur in thunderstorms or in a tropical storm/hurricane. Tornadoes often come with very little warning and it is crucial to identify the signs of imminent tornadic conditions.
Watch for tornado danger signs:
  • Dark, often greenish clouds – a phenomenon caused by hail.
  • Wall cloud – an isolated lowering of the base of a thunderstorm.
  • Funnel cloud – a visible rotating extension of the cloud base.
  • Roaring noise.
  • Cloud of debris.
  • Large hail.
EF Scale
Safety tips at home:
  • Go to basement, away from windows.
  • If there is no basement, go to lowest level possible, preferably a bathroom with no windows, lay down in tub.
  • Move or secure lawn furniture, trash cans, hanging plants or anything else that can be picked up by the wind and become a projectile.
Safety tips in a vehicle:
  • Immediately seek shelter in a sturdy building if you have the time.
  • Stay in the car with the seat belt on; put your head down below the windows, covering with your hands and a blanket if possible.
Severe Storm1