18) Times of Cell Mergers Associated with Tornadogenesis Relative To Tornado Start Time.pdf

During the cell merger analysis, all 208 cases were examined twice. The first examination pass identified cell mergers that occurred closer to the tornado start time. Within this first pass, clustering within the distribution was found at two time periods. The first was found to occur just a few minutes prior to the tornado start time. A second was found further out in time, generally between five and ten minutes prior to the tornado. During the first examination, it was observed that another cell merger was commonly occurring more than 10 minutes prior to the tornado start time. And this cell merger was often happening just before the start of the RFD surge. As a result, a second pass through the 208 cases was completed to identify cell mergers further out before the tornado start time. The cell merger that was identified during the second pass was called cell merger one, while the two cell mergers that were identified during the first pass were called cell merger two and three. After all the analysis was done, a cell merger two was found in more cases than a cell merger one. This is because a cell merger midway through the tornadogenesis process was slightly more common than a cell merger near the beginning of the tornadogenesis process. The first and second examinations were completely independent of each other, which revealed more detail concerning the distribution. Using the three periods of cell merger clustering, average times prior to the tornado start time were computed. The 208 case average of those times are listed below, with the number of cases identified for each time, and the percent of occurrence listed in Table 1. Read less