A single-cell thunderstorm forms when there is not much windshear (neither in direction nor strength) with height. The storm will be poorly organized, and the updraft is followed by a downdraft of cool air and precipitation, cutting off the updraft and terminating the storm growth cycle. A single cell storm will typically last less than one hour. If there is windshear with altitude, the storm usually becomes multicellular, having several growth cycles and lasting longer.
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