Dear Tom,
What is the difference between a tornado watch and a tornado warning?
— Joe Gilleran, Palatine
Dear Joe,
It’s been a record year for tornadoes in the Chicago area, so it is a very good idea to review the basic components of the warning system. A tornado watch is issued by the Storm Prediction Center in Norman, Okla., when forecasters feel that atmospheric conditions are primed for tornado development. The watch is often issued hours before the first storms develop, often when skies are clear. A tornado warning is issued by the local National Weather Service office when a tornado is sighted or when Doppler radar signatures indicate a high probability that a tornado has or is about to develop. For the public, a watch is a “heads-up” for possible severe weather, a warning means that severe weather is imminent and people in the path of the storm should take immediate cover.
