WRAL WeatherCenter Blog

Making warnings better

Posted March 5, 2010 12:24 p.m. EST
Updated February 7, 2011 8:05 p.m. EST

Watches and warnings are issued by the National Weather Service, and their primary purpose is to alert people who live in specific geographical areas of potentially dangerous weather conditions heading their way.

Watches are intended to alert citizens within a large area that widespread severe weather is expected to develop in the near future. If you live within the watch area, this is a good time to make sure you have a safety plan in place should a severe storm affect you directly. Warnings indicate that severe weather is imminent in the specific area outlined in the warning. It is then time to take immediate action to protect life and property to the extent possible.

Now we all know about "the boy who cried 'wolf.'" Well, if warnings are not specific enough, then someone like you may frequently hear about warnings in your county, but unless there is a loss of life or property near you, you chalk it up to yet another false alarm. In recent years, the National Weather Service has made significant strides in trying to narrow down the threat area.

At one time, severe weather warnings were issued for entire counties. Here’s why that is no longer done! Above is a map of Wake county, including Raleigh. The area of Wake county is 832 square miles. Now, let’s imagine a 1 mile wide tornado, destroying virtually everything in its path. This tornado is taking a path across Wake county that measures almost 44 miles (43.71 miles to be exact). After some basic math, one concludes that the area covered by this tornado is about 44 square miles. This means that the tornado only affects 5% of the entire county! So if a tornado warning is issued for all of Wake county, 95% of this county’s inhabitants will view the warning as a false alarm.

Thankfully, the National Weather Service is now issuing what is referred to as “storm based warnings”. This means that they are zeroing in on a specific storm, and issuing a warning based on the area likely to be affected by that storm. This warning area is still larger than the area that will end up being affected, but it is still a huge improvement, and one that leads to far fewer false alarms. It is worth noting that if two distinct storms are classified as severe in the same county, there will be 2 separate warnings issued within one county. Thus it is very important to listen to the details of a given warning, so as to make sure you know if you are in or out!

Warnings can be issued for tornadoes, severe thunderstorms or floods. And remember, a warning means that there is an immediate threat to property, and perhaps life within the warned area.  When a warning is issued for your area, take action immediately!

One way to stay ahead of severe weather is with WRAL WeatherCall. For a nominal fee, WRAL WeatherCall will monitor your home, workplace, or child's school 24 hours per day, 7 days per week. If severe weather threatens, Greg Fishel will call you with information about the storm and how to stay safe. Learn more about WRAL WeatherCall and sign up today!