What do thunderstorms and tornadoes have in common

Thunderstorms are most likely in the spring and summer months and during the afternoon and evening hours, but they can occur year-round and at all hours. Along the Gulf Coast and across the southeastern and western states, most thunderstorms occur during the afternoon. Thunderstorms frequently occur in the late afternoon and at night in the Plains states. What kinds of damage can thunderstorms cause?

Many hazardous weather events are associated with thunderstorms. Under the right conditions, rainfall from thunderstorms causes flash flooding, killing more people each year than hurricanes, tornadoes or lightning. Lightning is responsible for many fires around the world each year, and causes fatalities. Hail up to the size of softballs damages cars and windows, and kills livestock caught out in the open.

Strong up to more than mph straight-line winds associated with thunderstorms knock down trees, power lines and mobile homes. Tornadoes with winds up to about mph can destroy all but the best-built man-made structures. Where are severe thunderstorms most common? The greatest severe weather threat in the U. But, no place in the United States is completely safe from the threat of severe weather.

A watch can cover parts of a state or several states. Warnings mean there is a serious threat to life and property to those in the path of the storm. Taking shelter under an overpass is also not recommended, because most underpasses offer no place to hide. They can actually act like a wind tunnel and increase the storm's fury.

Away from home At work or school, know the emergency plans. If no specific plans exist, go to an interior hallway or small room on the building's lowest level. Avoid areas with glass and wide, free span roofs.

If you find yourself at the store or a mall and if you can't get to a basement or a designated shelter, go to the center of the lowest level of the building. Avoid windows and lie flat. Cover yourself with any handy object. What to Do After a Tornado? Immediately inspect yourself for injuries. Never move severely injured individuals unless they are in danger of additional injury. Seek medical attention immediately. Administer CPR immediately if you encounter someone who is not breathing.

Visit a doctor if you have a puncture wound. Follow local TV and radio broadcasts for updates. Use caution when entering damaged buildings. Wear protective clothing including long sleeves, pants, boots, gloves and other protective clothing when walking or working in rubble. Watch for broken glass and protruding nails. Never touch damaged power lines or objects near damaged lines. Report downed power lines to the utility company and local officials.

Avoid using candles to light homes without electricity. Instead, use battery-powered lights. Never place propane tanks, grills, camp stoves, generators and pressure washers inside a house, camper, or garage.

These devices can create carbon monoxide that can be fatal if breathed. Immediately seek medical attention if you become nauseated, light-headed or dizzy.. Always cooperate with local safety personnel.

Do not enter damaged areas without permission. You could get in the way of rescue personnel and become injured. Lightning According to the NOAA, over the last 20 years, the United States averaged 51 annual lightning strike fatalities, placing it in the second position, just behind floods for deadly weather.

During thunderstorms, stay inside. If you are outdoors, an automobile is a safe place to be. Indoors, keep away from doors, windows, stoves, sinks, metal pipes or other conductors. Don't use the telephone. Disconnect electrical appliances such as TVs and radios. Outdoors, minimize your height but don't lie flat. Do not take shelter under a tree. Stay away from wire fences or other metallic conductors. Avoid standing in small sheds in open areas. Your insurance policy typically covers the cost to repair roofs and cars, and other common hail damage.

You may have a higher deductible for wind and hail damage than you do for other types of claims. Talk to your insurance agent to find out about your coverage. A thunderstorm usually ends only 15 to 30 minutes after it begins, but other thunderstorms may start in the same area. With severe thunderstorms, the downdrafts are so intense that when they hit the ground it sends warm air from the ground upward into the storm.

The warm air gives the convection cells more energy. Rain and hail grow huge before gravity pulls them to Earth. Severe thunderstorms can last for hours and can cause a lot of damage because of high winds, flooding, intense hail, and tornadoes. Thunderstorms can form individually or in squall lines along a cold front. In the United States, squall lines form in spring and early summer in the Midwest where the maritime tropical mT air mass from the Gulf of Mexico meets the continental polar cP air mass from Canada Figure below.

Cold air from the Rockies collided with warm, moist air from the Gulf of Mexico to form this squall line. So much energy collects in cumulonimbus clouds that a huge release of electricity, called lightning , may result Figure below. The electrical discharge may be between one part of the cloud and another, two clouds, or a cloud and the ground. Lightning heats the air so that it expands explosively.

The loud clap is thunder. Light waves travel so rapidly that lightning is seen instantly. Sound waves travel much more slowly, so a thunderclap may come many seconds after the lightning is spotted. Thunderstorms kill approximately people in the United States and injure about Americans per year, mostly from lightning strikes.

Tornadoes , also called twisters, are fierce products of severe thunderstorms Figure below. As air in a thunderstorm rises, the surrounding air races in to fill the gap, forming a funnel. A tornado is a funnel shaped, whirling column of air extending downward from a cumulonimbus cloud. The formation of this tornado outside Dimmit, Texas, in was well studied. A tornado lasts from a few seconds to several hours. The average wind speed is about kph mph , but some winds are much faster.

A tornado travels over the ground at about 45 km per hour 28 miles per hour and goes about 25 km 16 miles before losing energy and disappearing Figure below. An individual tornado strikes a small area, but it can destroy everything in its path. Most injuries and deaths from tornadoes are caused by flying debris Figure below.

In the United States an average of 90 people are killed by tornadoes each year. Tornadoes form at the front of severe thunderstorms. Lines of these thunderstorms form in the spring where where maritime tropical mT and continental polar cP air masses meet. Although there is an average of tornadoes annually, the number of tornadoes each year varies greatly Figure below. The red region that starts in Texas and covers Oklahoma, Nebraska, and South Dakota is called Tornado Alley because it is where most of the violent tornadoes occur.

In late April , the situation was ripe for the deadliest set of tornadoes in 25 years. In addition to the meeting of cP and mT mentioned above, the jet stream was blowing strongly in from the west. The result was more than tornadoes reported throughout the day Figure below. The severe thunderstorms pictured in this satellite image spawned the deadliest set of tornadoes in more than 25 years on April , The cold air mass is shown by the mostly continuous clouds.

Warm moist air blowing north from the Atlantic Ocean and Gulf of Mexico is indicated by small low clouds. Thunderstorms are indicated by bright white patches. The entire region was alerted to the possibility of tornadoes in those late April days. But meteorologists can only predict tornado danger over a very wide region. No one can tell exactly where and when a tornado will touch down. Once a tornado is sighted on radar, its path is predicted and a warning is issued to people in that area.

The exact path is unknown because tornado movement is not very predictable. The intensity of tornadoes is measured on the Fujita Scale see Table below , which assigns a value based on wind speed and damage. Cyclones can be the most intense storms on Earth. A cyclone is a system of winds rotating counterclockwise in the Northern Hemisphere around a low pressure center. The swirling air rises and cools, creating clouds and precipitation.

There are two types of cyclones: middle latitude mid-latitude cyclones and tropical cyclones. Mid-latitude cyclones are the main cause of winter storms in the middle latitudes. Tropical cyclones are also known as hurricanes.

An anticyclone is the opposite of a cyclone.