Kansas and Oklahoma Tornado Shelters

Introduction:

This particular investigation is related to the frequency and sizes of tornadoes in Kansas and Oklahoma. Data has been provided for the location and size of each tornado for the years from 1995-2012. The data is broken up into two different block groups. The first being year 1995-2006 and the second being 2007-2012. The second block group also has the number of tornadoes for each county along with the location and size. There is a debate of whether or not to build tornado shelters in particular locations. Some of the public believe that there is a pattern as to where tornadoes are occurring with a higher frequency, while another group believes just the opposite. The other opinion is that not all places see tornadoes and therefore, it is an unnecessary waste of money to build these shelters. The state believes it is better to build the shelters in order to be on the safe side in case disaster strikes.

Methodology:

There were multiple tools that needed to be used in order to accurately assess whether or not shelters should be built. When modeling the data, it was broken up into the two different block groups. The first statistic to be mapped was the mean center. Each tornado location has an X coordinate and Y coordinate attached to it. In order to find the mean distance, all of these different points needed to be added up. The average from all the X points and Y points make up the two final points that represent the mean center. This shows where the exact middle is from all of the data points provided.

Figure 1 show the locations of Tornadoes in Kansas and Oklahoma for the years of 1995-2006. The locations are shown on the map by the size of the tornado's width in feet. The mean center and weighted mean center are also shown

The next tool used, which is very similar to mean center, is weighted mean center. Instead of only taking the average of the points, the weighted mean center also takes into consideration different frequencies of the grouped data. In other words, the points are weighted by frequencies which will most likely cause a different result than the mean center. 

Figure 2 show the locations of Tornadoes in Kansas and Oklahoma for the years of 2007-2012. The locations are shown on the map by the size of the tornado's width in feet. The mean center and weighted mean center are also shown

These two maps above (Figures 1 and 2) show the locations of tornadoes for the different years as well as the different mean centers and weighted mean centers. When looking at Figure 1, you notice that there is a shift of the weighted mean center to the south. This shows there were more tornadoes to the south of the mean center, rather than to the north of it. Figure 2 had a similar phenomena happen as what was shown in Figure 1. The one difference is the shift was in more of a southeastern direction, rather than straight south. 

Figure 3 show the locations of Tornadoes in Kansas and Oklahoma for the years of 1995-2012. The locations are shown on the map by the size of the tornado's width in feet. The mean center and weighted mean center are also shown

The map above (Figure 3) is the compilation of both Figure 1 and 2. When comparing the two results, the mean center has shifted north from the first block year to the second, but the weighted mean center has continued to move to the south. 

The second set of tools that were used involved standard distance. The standard distance is the spatial equivalent to the standard deviation. The standard distance shows where a particular percentage of tornadoes will occur around a particular point. For this example, 1 standard distance was used. The weighted mean center was the point used as the center maker for the standard distance. Since the weighted mean center was used, the map created was actually the weighted standard distance. You cannot create a weighted standard distance if there is not a weighted mean.

Figure 4 shows the tornado locations from
1995-2006 as well as where the weighted
standard distance is located. 

Figure 5 shows the tornado locations from
1995-2006 as well as where the weighted
standard distance is located. 

 The map to the left (Figure 4) shows the result of creating a weighted standard distance around the mean center. The map to the right (Figure 5) also shows the weighted standard distance. 

When comparing Figures 4 and 5, it is interesting to see the results. The map below (Figure 6) shows both maps combined together. Although Figure 3 had previously shown a shift to the south and east from the mean center to the weighted mean centers, The shift of weighted standard distance is to the northeast. Although this is the opposite of Figure 3, it is reasonable result. It is only comparing the results of the weighted mean center from the first block group to the second. Since it is only using these two points, the shift is understandable. 

Figure 6 is a compilation map of the weighted standard distance maps with the tornado locations overlaid to show where all the tornadoes have occurred from 1995-2012.

The last set of tools used was to find the standard deviation of the number of tornadoes that occurred. The data provided only had occurrences from the year 2007-2012, so the results will not reflect the two block groups that have been used for the duration of this project. The standard deviation shows allows you to see what areas are above or below the average number of tornado occurrences. The map below (Figure 7) shows how the standard deviation varies across the two different states. 

Figure 7 shows the standard deviation for the amount of tornadoes that occured from 2007-2012. The mean of this data set was four tornadoes. The map shows a large portion of tornadoes that occurred above the average were in central Kansas. 

Results:

While looking at the results of all the different, the assignment also called for finding Z scores for three different counties. The counties were Russel, Co, KS, Caddo, Co. OK and Alfalfa, Co. OK. The Z score results for the counties were the following:

Russell: 4.80

Caddo: 2.09

Alfalfa: .23

After looking at the Z score for those three counties, the assignment also wanted to know how many tornadoes will occur 70% and 20% of the time for the next five years. The results are as follows:

There is a 70% chance that one tornado will occur over the next five years in the study area. There is a 20% chance that seven tornadoes will occur over the next five years in the study area. 

Conclusion:

When looking at all of the maps and the numbers associated with them, the findings were interesting. When looking at the probability of tornadoes occuring, according to the Z scores, the number seems very low. This would mean that it would not be a necessity to build shelters. On the other hand, when analyzing the different maps, it seems as if some areas are more prone to tornadoes and it may be a good investment to build storm shelters. 

Overall, it is hard to estimate where shelters should be built due to the large size of the study area. In order to get a more accurate representation of where shelters should be located, multiple maps may need to be made in specific locations within Kansas or Oklahoma.