Quantitative Methods in Geography: Post 1: Tornadoes

This is a study of the spatial distribution of tornadoes in Kansas and Oklahoma, the middle of "Tornado Alley". Tornadoes do not occur in just part of this region, but rather their distribution changes with the progression of time. In order to best to determine what areas are most at risk, it is necessary to investigate where tornadoes have occurred and if the locational trends will allow for the prediction of future tornado occurrences. The States' of Kansas and Oklahoma desire to build storm shelters in areas likely to encounter more tornadoes. In order to determine those areas, it is necessary to weigh tornado frequency, tornado size, as well as changing weather patterns throughout time.

To determine the locations of future storms, several points and distances will be calculated. The Mean Center of The tornado locations will be calculated, to determine the average location for all tornadoes in a time period. This will provide a simple midpoint from which future observations will be based. Another point to be calculated is the Weighted Mean Center; a more complex average of the tornado locations based off of their widths. After the mean center and weighted Mean center are calculated, the standard distance and weighted standard distance may be calculated. The standard distance is the spatial equivalent to the standard deviation, and allows the map-reader to more closely identify the spatial trends of the data around the mean center. The weighted Standard distance shows how data is distributed around the weighted mean center.

These values will be calculated from data sets of tornado locations between 1995-2006, and 2007-2012. A data set showing the number of tornado occurrences per county between 2007-2012 will also be used.

As time progressed, the distribution of tornadoes varied, but not by much. In figure 1, tornadoes are seen in three groups: a band running from east to west across the middle of Oklahoma, a bear and running from north by northeast to south by southwest from Kansas to Oklahoma, and a third band and running from Northeast to Southwest across Kansas to the panhandle of Oklahoma. In figure 2, only two major groups are seen. There is a line of large tornadoes that occurred across Oklahoma in a pattern following east by north east to west by Southwest pattern. The second line of storms stretched almost perfectly east to west with the epicenter of storm activity directly underneath the weighted mean center. Figure 3 indicates that when will the locations of tornadoes they have changed throughout the different time periods, the location around which they are centered had not changed. Comparison between maps four and five shows how the distribution of tornadoes has become more centralized in recent years. In figure 6 this more visibly clear, as a majority of all major tornadoes occurred in the region of overlap between The 90s and 2000s weighted standard distances. Figure 7 shows how the frequency of tornado occurrences compares to the mean of 4.0, with a standard deviation of 4.3. Figure 7 shows that the concentration of tornado occurrences is most centered in Kansas, just north of the border with Oklahoma. The calculations suggest it is highly unlikely any counties will sustain the occurrence of more than 8.3 tornadoes within a five year period, but most will encounter at least four within the same time period.

The result of this analysis shows an extremely varied distribution of tornado locations throughout the region of Oklahoma and Kansas. The patterns of storm system occurrences have varied significantly, but within a limited area. When collating the weighted standard distance of the 1990s tornado locations with the weighted standard distance of the 2000s tornado locations, it becomes more evident that the area where the two intersect is a hotbed of storm activity. While many of the counties do not wish to build storm shelters, it would seem prudent to require them in the counties with tornado counts well above average, and strongly suggest the construction of them in the other counties within both weighted mean centers.