Being ready for severe weather isn't just about having a well-stocked supply kit. It's also important to understand the terminology used in severe weather situations! One of the most common questions people ask me is, "What's the difference between a Watch and a Warning?" I can understand why it's confusing, especially since the two seem to often be right on top of each other! But it's not as tough as it may seem.
A Severe Thunderstorm Watch means that severe thunderstorms are likely to happen during the Watch timeframe. It does not mean that a severe storm is actually happening at the moment. It might be completely dry in your neighborhood when a Severe Thunderstorm Watch is issued, or it might be raining, or perhaps there is even a thunderstorm over your town.
A Severe Thunderstorm Warning means that a thunderstorm is happening in the designated area (see the picture below).
|An example of Watches and Warnings in our area. The light yellow shading is for the Watch,|
and the opaque shading indicates areas where Severe Thunderstorm Warnings are in effect.
A storm is considered severe if its winds are 60mph or stronger, or if the hail is quarter-sized or larger. So, it's possible to have a thunderstorm in your area without a Severe Warning in effect, because that storm cell might not have one of the severe characteristics I described above.
The same rules about a Watch and a Warning apply for tornado alerts. A Tornado Watch means that a tornado is possible within the watch timeframe. A Tornado Warning, however, is much more serious, because it means that a tornado has either been spotted by a trained observer, or that rotation has been detected by Doppler radar.
If you're watching WUSA9 and a Warning message is displayed on your TV screen, but it's not raining in your town, that means there is a severe storm occurring elsewhere in our viewing area. (Our area is huge- we cover from Southern Maryland all the way to Hagerstown and points west!) Take note of the county or counties included in the Warning. Some of the counties in our area, like Prince George's and Fauquier, are so big that a severe storm could be occurring in one part of the county, while another part of the county is dry. You can always check out the radar if you're unsure whether a warning affects you. Or, even better, you can sign up for First Alert Weather Call. If you have this service, you'll only get a phone call if you're directly in the path of a severe storm.