Differences Between Storm Warnings & Watches

Governmental Agency

• Located in Norman, Oklahoma, the Storm Prediction Center, or SPC, monitors rain, snow, fire, thunderstorms and tornadoes for the continental US. The SPC issues watches, but not warnings, for potentially dangerous weather conditions. The SPC is the only organization that issues severe thunderstorm, tornado and winter storm watches. The National Weather Service has local offices all over the US. This agency issues precise warnings for particular locations. The National Hurricane Center issues watches and warnings for tropical storms and hurricanes.

Advance Notice

• Watches are issued early enough so that people in affected areas have a chance to prepare. For example, winter storm watches indicate that there is a possibility of severe winter weather in the next 12 to 36 hours. Similarly, the National Hurricane Center issues hurricane watches 48 hours in advance. With advance notice, you have a chance to get supplies, board windows and evacuate, if necessary. In contrast, the average warning time for a tornado is 15 minutes. Once a warning is issued, you need to seek shelter immediately.

Geographical Area

• Watches typically affect 25,000 square miles. Because warnings are issued by local National Weather Service offices, warnings are much more geographically accurate. Local radar allows the National Weather Service to track precisely the path of the storm.

Degree of Certainty

• Watches indicate the potential for severe weather events while warnings indicate that severe weather is expected or has already been observed.

Severity

• Some people believe that one of the differences between a storm watch and a storm warning is the severity of the storm; however, there is no difference in severity between storms identified in a watch and a warning.