WeatherWeather Blog


Thunderstorm Development and Severe Criteria

Posted at 1:47 PM, Mar 27, 2018
and last updated 2018-03-28 08:41:29-04

Thunderstorms are common occurrences across Nebraska and Iowa, and we have already started experiencing storms this year. As you know, a thunderstorm is a rain shower that contains thunder and lightning. But what is the process for thunderstorm development? 

The first stage of development is the cumulus stage. Rising air, called an updraft, pushes the cumulus cloud upward and it begins to look like a tower. There is not much, if any, rain during this stage, though there may be a little bit of lightning.  

Next, is the mature stage. As the updraft feeds the storm, rain begins to fall, which makes a downdraft. The downdraft and rain-cooled air reach the ground and spread out, forming a line of gusty winds, called the gust front. During this stage is mostly likely when you will experience heavy rain, frequent lightning, hail, strong winds, and tornadoes. 

Finally, thunderstorms begin the dissipating stage as the downdraft becomes stronger than the updraft. The gust front is farther ahead of the storm and cuts off the warm moist air that was feeding the storm. Rain begins to let up, but lightning can still be dangerous during the dissipating stage. 

During the mature stage, a thunderstorm may become severe if it produces quarter size hail or larger, winds at least 58 MPH, and/or a tornado.  

While not every severe thunderstorm produces a tornado, it is still best to shelter inside your safe room when a warning is issued. During a thunderstorm that is not severe, you should stay inside and away from windows, pipes, and corded electronics. 

Severe Weather Awareness Week continues this week with the following topics: 

Wednesday: Tornadoes 
Thursday: Lightning 
Friday: Flooding 
Saturday: How to Report Severe Weather