Comprehensive Analysis of Tornadic Daily Cycles from 1979 to 2013.
Mentor 1
John Frye
Location
Union Wisconsin Room
Start Date
24-4-2015 10:30 AM
End Date
24-4-2015 11:45 AM
Description
Tornadoes can occur at any time throughout the diurnal cycle; however, the probability of them occurring is not constant throughout that cycle. Historically, tornado occurrences peak in the United States during the mid-afternoon between noon and sunset. The first stages of this research were 1) to verify the exact timing of the diurnal peak for tornadoes from 1979-2013 and 2) to analyze the variations in the spatial patterns of tornado occurrences throughout the diurnal cycle. Once that stage was completed additional research questions emerged and further investigation was needed. The primary question that emerged was whether a significant change in the timing and diurnal distribution of tornadoes across the United States had occurred. To analyze this question the tornado events were divided into three temporal groups (1979-1989, 1990-2000, and 2001-2013). The Kruskal-Wallis and Mood’s Median tests were then employed to determine the changes in the diurnal pattern across space and time. When examining all tornado events, it was found that the afternoon (noon through 6 pm local time) and evening (6 pm to midnight) showed a statistically significant increase in tornado frequency since 1979. However, when limiting the occurrences by region, season, or damage-scale rating, the changes in the frequency did not follow the same statistically significant pattern.
Comprehensive Analysis of Tornadic Daily Cycles from 1979 to 2013.
Union Wisconsin Room
Tornadoes can occur at any time throughout the diurnal cycle; however, the probability of them occurring is not constant throughout that cycle. Historically, tornado occurrences peak in the United States during the mid-afternoon between noon and sunset. The first stages of this research were 1) to verify the exact timing of the diurnal peak for tornadoes from 1979-2013 and 2) to analyze the variations in the spatial patterns of tornado occurrences throughout the diurnal cycle. Once that stage was completed additional research questions emerged and further investigation was needed. The primary question that emerged was whether a significant change in the timing and diurnal distribution of tornadoes across the United States had occurred. To analyze this question the tornado events were divided into three temporal groups (1979-1989, 1990-2000, and 2001-2013). The Kruskal-Wallis and Mood’s Median tests were then employed to determine the changes in the diurnal pattern across space and time. When examining all tornado events, it was found that the afternoon (noon through 6 pm local time) and evening (6 pm to midnight) showed a statistically significant increase in tornado frequency since 1979. However, when limiting the occurrences by region, season, or damage-scale rating, the changes in the frequency did not follow the same statistically significant pattern.
