Tornado– A violently rotating column of air in contact with the ground and extending from the base of a thunderstorm. A condensation funnel does not need to reach to the ground for a tornado to be present; a debris cloud beneath a thunderstorm is all that is needed to confirm the presence of a tornado, even in the total absence of a condensation funnel.

Fujita Scale - (or F Scale) - A scale of wind damage intensity in which wind speeds are inferred from an analysis of wind damage:

F0 (weak): 40- 72 mph, light damage.
F1 (weak): 73-112 mph, moderate damage.
F2 (strong): 113-157 mph, considerable damage.
F3 (strong): 158-206 mph, severe damage.
F4 (violent): 207-260 mph, devastating damage.
F5 (violent): 261-318 mph, (rare) incredible damage.

Tornado Watch - A National Weather Service (NWS) statement issued that indicates that tornadoes are possible in and close the watch area  (i.e., that conditions are more favorable than usual for its occurrence). Their size can vary depending on weather situation.  They are usually issued for a duration of 4 to 8 hours.  They are usually issued well in advance of the actual occurrence of severe weather.  During the watch, people should review tornado safety rules and be prepared to move to a place of safety if threatening weather approaches.   It is a recommended that you plan, prepare, and increase your tornado awareness (i.e., be alert for changing weather and approaching storms). Know what other cities or counties are in the watch area by listening to NOAA Weather Radio or your local radio/television stations. Think about what to do if the tornado materializes.

Tornado Warning - A statement issued by NWS local offices indicating that a tornado is either imminent or has been sighted or indicated by weather radar. A warning indicates that people in the affected area  need to seek safe shelter inmediatly  to protect life and inmediat action to protect property.  Tornado warnings can be issued with or without a Tornado Watch already being in effect.  Tornado warnings are usually issued for a duration of 30 minutes

Tornado Safety Rules

• In a home or building, move to a pre-designated shelter, such as a basement.
• If an underground shelter is not available, move to a small interior room or hallway on the lowest floor and get under a sturdy piece of furniture. Put as many walls as possible between you and the outside. Stay away from windows.
• Do not try to outrun a tornado in your car; instead, get out of the vehicle and leave immediately for safe shelter.
• If caught outside or in a vehicle and safe shelter is not available, locate a nearby ditch or depression, lie flat in it and cover your head with your hands.
• Be aware of flying debris. Flying debris from tornadoes causes most fatalities and injuries.
• Mobile homes, even if tied down, offer little protection from tornadoes. You should leave a mobile home and go to the lowest floor of a sturdy nearby building or storm shelter.

Kids' Guide to Tornadoes

• Kids' Guide to Tornadoes