Tackling Tornado Trends

STA 313 - Spring 2024 - Project 1

Team Two

Introduction

Our primary dataset is the tornadoes dataset:

  • contains characteristics of tornadoes within the US and US territories (e.g. date and time of occurrence, magnitude, path length)
  • sourced from TidyTuesday that uses the NOAA’s data related to tornadoes from 1950 to 2022

We are only analyzing tornadoes in the contiguous US 48 states and D.C.

Goals:

  • explore the characteristics of tornadoes and how they change based on their environmental conditions

  • dig into the negative impacts on populations across the country

Questions

  1. How may the nature of tornadoes vary by the location they occur in?
  2. How may the nature of tornadoes vary by the season they occur in and over time?

Figure 1: Tornadoes With Greater Magnitudes Often Have Larger Path Lengths

Tornadoes with greater magnitudes often have larger path lengths. Figure 1 is a ridgeline plot that visualizes the distribution of tornado path lengths for each category of magnitude on the Enhanced Fujita scale from zero to five with the path length on the x axis and magnitude categories on the y axis. The plot is faceted by region, so these path length distributions can be seen by magnitude categories across each of the five regions in the United States. There is a positive correlation between the path length, which is an indicator of the distance travelled by tornadoes, and the magnitude of tornadoes across all regions. Certain regions like the Midwest, Southeast, and Southwest tend to have tornadoes of greater magnitudes compared to regions like the Northeast, which has not had any tornadoes of magnitude 4, and the West, which has not had any tornadoes of magnitude 4 and 5.

Figure 1: How do tornado magnitude and path length relate and vary by region?

Figure 2: Average Magnitude and Frequency of Tornadoes Across U.S. States

Figure 2 is a simple features plot in the form of two side by side map plots that represent the contiguous United States. One map has states colored by the average magnitude of the tornadoes that have originated there, and the other map has states colored by the amount of tornadoes that have originated there. These maps show that grouping trends in tornado severity and frequency by region is oversimplifying and generalizing such trends too much. Instead, tornado trends are more similar in states along the same longitudes. For example, tornadoes in states along close longitudinal lines in the center right of the U.S., such as Texas, Kansas, Oklahoma, and Iowa, tend to have similar and some of the highest tornado frequencies and average magnitudes even though they span different regions.

Figure 2: How do tornado magnitude and frequency vary by state?

Figure 3: Greatest Amount and Magnitudes of Tornadoes have Consistently Occurred in Spring

The figure is a stacked bar chart titled “Greatest Amount and Magnitudes of Tornadoes have Consistently Occured in Spring over Time” that displays the proportion of tornadoes at each different level of magnitude that happened in each season in each decade. Specifically, across the horizontal axis (which is the proportion of tornadoes in each season as a percentage), each column represents tornadoes at different magnitudes in a given decade, whereas across the vertical axis (which is the magnitude of the tornado), each row represents tornadoes at a given magnitude that happened in different decades. Additionally, the bar chart is also colored by season to show the proportion of tornadoes that happened in each season. We observe that the tornadoes that happened in Spring have consistently the greatest proportion over time over most of the different magnitude levels. Besides, the higher the magnitude, the larger the proportion of tornadoes that happened in Spring over time, and in the past two decades (the 2000s - the 2010s), all tornadoes of magnitude 5 (highest magnitude) happened in Spring.

Figure 3: How do tornado magnitude and frequency vary by season and decade?

Figure 4: Spring Consistently has the Most Average Fatalities per Decade

This figure is a combined plot consisting of a line chart and a stacked column chart, titled “Spring Consistently Has the Most Average Fatalities per Decade”. The horizontal axis is the decade in which tornadoes happened, and the vertical axis on the left-hand side is the average yearly fatalities caused by tornadoes. We also added a secondary vertical axis on the right-hand side for the line chart and it represents the average magnitude of all tornadoes that happened in each decade. Additionally, we also color both charts by the season where the tornado occurred. Based on the stacked column chart, we can see that Spring is consistently the season with the highest fatalities, and the total fatalities generally decreased from the 1950s to the 2000s, but have rebounded slightly from the 2000s to now. Based on the line chart, we observed the same trend that the average magnitude of tornadoes generally decreased from the 1950s to the 2000s and rebounded slightly from the 2000s to now. Additionally, Winter has consistently been the season with strongest average tornado magnitude.

Figure 4: How does tornado damage vary by season and decade?