TORNADO
NATURE'S MOST VIOLENT STORM

What is a tornado? A tornado is a violently spinning column of air that stretches from the cloud to the ground. All tornadoes have a "V" shaped funnel cloud, but a funnel cloud...which sometimes drops from a cloud...is not a tornado unless it reaches the ground. Some tornadoes may not have a visible funnel. Tornadoes can only be seen if clouds or rain get caught in the funnel cloud or if the tornado picks up dirt or debris from the ground.
 
 

Where do tornadoes come from? Tornadoes come from thunderstorms. Many strong thunderstorms form and never come close to producing tornadoes. Even when the ingredients look really good for tornadic thunderstorms, as in a Tornado Watch, not every thunderstorm forms a tornado. The truth is that we don't fully understand why some strong thunderstorms develop tornadoes and some don't. The most destructive and deadly tornadoes happen in supercells -- which are thunderstorms with a spinning center. If the winds at different heights of the thunderstorm are coming from different directions, the storm will begin to spin and a supercell may form.
 
 

Where do tornadoes happen? Tornadoes have occurred in every state in the United States. Most strong tornadoes happen in the central plains of the United States, especially in states like Texas, Oklahoma and Kansas but they can happen in any state. They also ccur in many other parts of the world, including Australia, Europe, Africa, Asia, and South America.
 
 

When do tornadoes happen? Tornadoes can occur on any day of the year and at any hour. Most strong or violent tornadoes form during the spring and summer; the tornado season comes early in the spring in the south because the area warms earlier. In the southern states, most tornadoes occur from March through May, while main months in the northern states are during the summer. In some states, including Mississippi, a second short tornado season occurs in the fall. Tornadoes are most likely to occur between 3 and 9 p.m. but have been known to occur at all hours of the day or night.
 
 

What makes tornadoes so dangerous? Tornadoes are dangerous because of the strong winds they make. Winds in the tornado are tightened around a small area, which makes wind speeds dangerously high. It's like ice skaters doing spins on the ice. The skaters pull their arms in close to their body to spin really fast. When the strorm winds can somehow be drawn into a smaller spinning column, the winds really speed up. Tornado winds can be as high as 300 mph in the most violent tornadoes. Wind speeds that high can throw cars, rip homes apart and turn broken glass and other garbage (called debris) into deadly flying missiles. The biggest danger to people from tornadoes is from flying debris and from being thrown around in the wind.
 
 

How fast do tornadoes move and how long do they last? Most tornadoes move around 30 or 40 miles an hour but tornado speed can be anything from zero, where they sit over one spot until they die, or as fast as 70 mph. Most tornadoes move from the southwest to the northeast, but tornadoes have been known to move in any direction. They can last from several seconds to more than an hour. The longest-lived tornado in history is really unknown, because so many of the long-lived tornadoes reported from the early 1900s and before are now believed to have been a set of several tornadoes instead of one single tornado. Most tornadoes last less than 10 minutes.
 
 
 
 

The Fujita Tornado Damage Scale
Developed in 1971 by T. Theodore Fujita of the University of Chicago

	F-Scale Number	Intensity Phrase	Wind Speed	Type of Damage Done
	F0	Gale Tornado	40-72 mph	Some damage to chimneys; breaks branches off trees; pushes over shallow-rooted trees; damages board signs.
	F1	Moderate Tornado	73-112 mph	Beginning of hurricane wind speed; peels surfaces off roofs; mobile homes overturned; cars pushed off the road.
	F2	Significant Tornado	113-157 mph	Roofs torn off some houses; mobile homes destroyed; boxcars pushed over; large trees snapped or uprooted.
	F3	Severe Tornado	158-206 mph	Roof and some walls torn off well constructed houses; trains overturned; most trees in forest uprooted.
	F4	Devastating Tornado	207-260 mph	Well-constructed houses destroyed; buildings blown off weak foundations; cars thrown.
	F5	Incredible Tornado	261-318 mph	Strong frame houses lifted off foundations and carried considerable distances to disintegrate; cars and other automobile sized missiles fly through air over 300 feet; trees debarked; steel re-inforced concrete structures badly damaged

 
 
 
 

Tornado Myths:

MYTH:  You should open the windows before a tornado comes to help prevent damage to the building.
FACT:   Don't waste time opening windows. Leave the windows alone and take shelter immediately. Opening the windows is useless and can be very dangerous. You may be injured by flying glass trying to do it. If the tornado hits your home, it will blast the windows open anyway.
 

MYTH:   Highway overpasses are a safe place if you are caught on the road when you see a tornado coming.
FACT:    By climbing under an overpass, you will be exposed to stronger winds and flying debris. Deadly flying debris can be blasted into the spaces between the bridge and grounds and it can kill people hiding there. People have been killed or injured when tornado winds have blown them out from under bridges.
 

MYTH:  Low pressure with a tornado causes buildings to explode.
FACT:  When pieces of brick, metal or other things broken apart by the tornado break through a window, tornado winds rush in and sometimes rip the roof off from the inside. This causes the walls to fall outward and it may look like the house has exploded.
 

MYTH:   Areas near rivers, lakes, and mountains are safe from tornadoes.
FACT:   No place is safe from tornadoes. In the late 1980's, a tornado swept through Yellowstone National Park leaving a path of destruction up and down a 10,000 ft. mountain.
 
 
 
 
 
 

 HOW CAN I KEEP MYSELF SAFE?
 

 NWS STORM PREDICTION CENTER TORNADO FAQS
 

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