SKYWARN 2018, a storm spotter class was presented by David Cavanaugh, Warning Coordination Meteorologist for the National Weather Service, in Little Rock, on March 8, 2018. The Sun Times attended the two hour class held at the Cleburne County Library.
Cavanaugh detailed why storm spotters are critical due to the limitations of Radar. The radar that serves this area is located at the North Little Rock airport. Radar works by sending out energy and when this energy hits something, some of it is returned to the radar and an image is made. It strike's whatever is falling from the sky, in a thunderstorm, rain and hail. Doppler radar can measure the speed of whatever is going either towards it or away from it. Radar cannot see clouds, so a whole picture cannot be made with radar alone. It primarily measures upper and mid level disturbances and misses what is happening near the ground and thus storm spotters become necessary. They can see what is happening on the ground and this added with the information radar collects creates a more complete picture of the storm. Radar can measure rotation but can't spot a tornado. Cavanaugh states "We basically need eyes on the storm to tell us what's happening near the ground". Radar only indicates something is falling from the sky but can't differentiate between rain, hail, sleet or snow.
Cavanaugh talked about the different kinds of thunderstorms and how to identify them. For a thunderstorm, to work, it must contain heat, instability, lift, humidity, and to be dangerous, wind shear, which is a change in wind direction or speed with height. There are three types of thunderstorms. The Single Cell is a weak storm that only creates a small localized threat, it normally goes straight up, produces rain and collapses straight down. It is usually brief, weak, and contains no wind shear, although localized damage can occur. The Multi Cell, Multi Cell Line, or Multi Cell cluster, can create moderate damage from winds and hail, flash flooding, and occasionally produces a weak tornado. The Super Cell is almost always a violent storm with rain, hail, high winds and tornadoes. It's very similar to to a single cell except as the warm air is rising it begins to rotate allowing the storm to be much stronger, to produce hail and possibly a tornado. To. produce a tornado a storm must contain an updraft.
Participants learned how to visually identify which clouds indicate updrafts and downdrafts and other potential signs of a tornado, and how to report these sightings to the NWS. Cavanaugh stressed the importance of having an emergency radio, cell phone or other means to get emergency weather alerts. The latest weather forecast can be found at www.weather.gov/LZK.