What is the difference between a ‘warning’ and a ‘watch’?

Print Friendly
What is the difference between a ‘warning’ and a ‘watch’?
weather radar with green, red, blue zones

A weather watch indicates the possibility of hazardous weather, while a warning means that hazardous weather is occurring, is about to occur or is very likely to occur.

A watch is intended to provide people with enough time to set safety plans in motion for possible hazardous weather. A warning indicates that conditions pose a threat to life or property and people in the warning area should take appropriate protective action.

Watches and warnings outline areas where the weather may occur. Pinpointing the location of hazardous weather in advance is extremely difficult. For this reason, watches are usually issued for large regions, sometimes covering several states. Warnings are issued for much smaller areas, often only a county or two, because they are based on actual observations of hazardous weather.

The National Weather Service issues weather watches and warnings under specific weather conditions. A severe thunderstorm watch means that conditions are favorable for the development of severe thunderstorms in and near the watch area. A warning means that a severe thunderstorm has been sighted visually or indicated by radar and it is producing hail 0.75 inch or larger in diameter and/or winds of at least 58 mph.

Finally, a weather advisory may be issued when actual or expected weather conditions are not hazardous, but may cause inconvenience or concern.

Steven A. Ackerman and Jonathan Martin are professors in the Department of Atmospheric and Oceanic Sciences at UW-Madison, are guests on the Larry Meiller‘s WHA-AM radio show the last Monday of each month at 11:45 a.m.