One of the more confusing things about the weather is the terminology we use. A forecaster’s goal is to make accurate weather predictions and communicate them clearly to the public so that everyone has an idea of what to expect of Mother Nature. When the weather is nice, the job is pretty easy. When the weather is threatening, the job is much more complicated. A forecast can be difficult enough to make accurately as far as timing and the geographic location of the worst of a storm. Clearly explaining the threats with that storm and how they will affect people can be a challenge in itself.
For decades, the National Weather Service has issued a plethora of products – 14 just for winter weather – to try to explain the potential dangers of a storm system to the masses. There are three that we in the Triangle see much more often than the others: advisory, watch, and warning. A Winter Weather Advisory is issued when conditions (current or imminent) could pose hazards that require people to be cautious such as slippery roads caused by black ice. A Winter Weather Watch is issued when the forecast is taking shape and there is potential for danger, but the exact timing or location of an event is still in question. A Winter Weather Warning is issued when a dangerous hazard is already happening or will be soon.
The advisory, watch, and warning definitions are similar for weather such as severe thunderstorms and tornadoes. A watch in those cases means that conditions are right for them to form, and a warning means that it is happening at the time the warning is issued. The watch can last for several hours, while a warning is typically made for a shorter time frame, usually an hour or less.
Despite how long these products have been used, the general public still seems confused by the terminology. There is a push within the field of meteorology to change the way these products are issued by simplifying the words and phrases and being more specific with the hazardous conditions expected. The National Weather Service is currently asking for feedback on a proposal for simplification. You can see the proposal and leave comments by visiting http://nws.weather.gov/haz_simp/ .