Tornado Watch & Tornado Warning
A tornado watch means that conditions are favorable for producing a particular weather event, but that it has not formed yet. Watches alert the public that they need to pay closer attention than usual to the weather, just to be safe. A tornado watch is issued when atmospheric conditions could cause tornadoes to form, although none have formed yet.
A tornado warning means that a particular weather event has formed and that it threatens the area under the warning. A tornado warning means that a tornado is actually present and moving in the warn vicinity. Residents should take immediate shelter in a tornado warning.