TORNADO WATCH Conditions are favorable for the development of tornadoes in and close to the watch area. Watches are usually in effect for several hours, with 6 hours being the most common.

TORNADO WARNING Tornado is indicated by radar or sighted by storm spotters. The warning will include where the tornado is and what towns will be in its path.

SEVERE THUNDERSTORM WATCH Conditions are favorable for the development of severe thunderstorms in and close to the watch area. Watches are usually in effect for several hours, with 6 hours being the most common.

SEVERE THUNDERSTORM WARNING Issued when a thunderstorm produces hail 3/4 of an inch or larger in diameter and/or winds which equal or exceed 58 mph. Severe thunderstorms can result in the loss of life and/or property. Information in this warning includes: where the storm is, what towns will be affected, and the primary threat associated with the storm.

SEVERE WEATHER STATEMENT Issued when the forecaster wants to follow up a warning with important information on the progress of severe weather elements.

FLASH FLOOD WATCH Indicates that flash flooding is possible in and close to the watch area. Those in the affected area are urged to be ready to take quick action if a flash flood warning is issued or flooding is observed.

FLASH FLOOD WARNING Signifies a dangerous situation where rapid flooding of small rivers, streams, creaks, or urban areas are imminent or already occurring. Very heavy rain that falls in a short time period can lead to flash flooding, depending on local terrain, ground cover, degree of urbanization, degree of man-made changes to river banks, and initial ground or river conditions.

Source: National Weather Service: Louisville, KY

http://www.crh.noaa.gov/lmk/sev.htm