DISCUSSION: In light of the recent severe weather event which impacted many parts of the south-central United States, there was strong outflow emanating from the leading-edge of certain severe thunderstorms which impacted parts of southern Missouri. As you can clearly see in the image attached above, a neat cloud referred to as a "roll cloud" was observed by many people across the region as a particular thunderstorm. It is worth noting that roll clouds form as a result of very strong and efficient lifting of warm moist air ahead of an approaching strong-to-severe thunderstorm line. As this warm, moist air was quickly lifted over the leading-edge, the roll cloud formed as a consequence of rapid condensation of low-level moisture aggregating into what could be visualized as a roll cloud as shown above. Hence, in any situations wherein a roll cloud moves through a given region out ahead of a strong-to-severe thunderstorm, a roll cloud is typically an indication of a powerful thunderstorm approaching the given region.
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©2017 Meteorologist Jordan Rabinowitz