2021 12/07 Cort Scholten QLCS Tornadoes
Our speaker for this evening was our vice president, Cort Scholten, a lead forecaster at the local National Weather Service office. His topic was about tornadoes originating from non super cell thunderstorms.
The vast majority of tornadoes are produced by super cell thunderstorms but occasionally, small, weak, and short lived tornadoes can form in non super cell conditions. They occur within what is called a Quasi-Linear Convective System or QLCS. Quasi-linear because you rarely ever get perfectly straight lines in nature. A sample radar image may look like this.
These types of tornadoes are rare enough, small enough, and frequently obscured by rain resulting in the fact there has never been a photo of one taken in Michigan. Fortunately, they usually only last a few moments and are of F0 or F1 intensity, however, in extremely rare cases, can reach F3 intensity.
The parameters necessary for a non super cell tornado to develop are rather technical and require a good amount of training for a radar operator to recognize. Even when all the conditions seem to be met, only about 25% of the time will a tornado of this type occur. The NWS in a situation like this will usually issue a severe thunderstorm warning with the notation that a small tornado or brief spin-up is possible.
To see the entire presentation move your mouse over the image below and click on the arrow at the top right corner to "pop-out" the pdf.
Scholten_QLCS_Tornadoes.pdf