Fact Check: Are EF5 tornadoes rare?

Are EF5 Tornadoes Rare?

Introduction

The claim that "EF5 tornadoes are rare" has gained traction in discussions about severe weather phenomena, particularly in the context of climate change and tornado frequency. EF5 tornadoes, which represent the highest classification on the Enhanced Fujita scale, are characterized by their extreme wind speeds and destructive potential. This article aims to explore the validity of this claim by examining available data and expert opinions on the frequency of EF5 tornadoes in the United States.

What We Know

Definition and Classification: EF5 tornadoes are classified as those with estimated wind speeds exceeding 200 mph, capable of causing "incredible" damage, including the complete destruction of well-built houses 1 4.
Historical Data: According to the National Weather Service, since 1950, there have been a total of 50 tornadoes rated F5 before 2007 and 9 rated EF5 since the scale was introduced 1 10. This indicates a total of 59 EF5 tornadoes over a period of more than 70 years.
Current Trends: Research indicates that there has been a notable decline in the frequency of EF5 tornadoes in recent years. For example, the last EF5 tornado occurred in Moore, Oklahoma, on May 20, 2013 2 4.
Tornado Frequency Statistics: A study analyzing tornado frequency from 1995 to 2014 found that only 0.57% of all tornadoes in the U.S. were classified as violent (EF4 or EF5) 8. This suggests that while tornadoes are common, the most severe classifications are significantly less frequent.
Geographic and Temporal Distribution: Tornadoes are more likely to occur in certain regions, notably the central U.S., often referred to as "Tornado Alley." However, the frequency of EF5 tornadoes has not followed the same trends as weaker tornadoes, which have been more common 3 9.

Analysis

The claim that EF5 tornadoes are rare is supported by empirical data, which shows a low occurrence rate relative to the total number of tornadoes. The National Weather Service's data and the analysis by Elsner et al. 8 provide a quantitative basis for this assertion. However, the rarity of EF5 tornadoes can also be contextualized by considering the following factors:

Data Reliability: The sources of data, such as the National Weather Service and NOAA, are generally regarded as credible and authoritative in meteorological research. However, the Wikipedia entry 2 may not be as reliable due to its open-edit nature, which can introduce inaccuracies.
Methodological Concerns: The transition from the Fujita scale to the Enhanced Fujita scale in 2007 could impact the comparability of data across time periods. The criteria for EF5 ratings may have changed, potentially affecting the reported frequency of these tornadoes 4.
Potential Bias: Some sources may have an inherent bias based on their focus or the agendas of their authors. For instance, articles discussing climate change may emphasize the rarity of EF5 tornadoes to argue for or against specific climate policies.
Need for More Information: Additional longitudinal studies that analyze the frequency of EF5 tornadoes over a longer time frame, as well as their relationship to climate variables, would be beneficial in providing a more comprehensive understanding of trends.

Conclusion

Verdict: True

The claim that EF5 tornadoes are rare is substantiated by historical data indicating that only 59 EF5 tornadoes have been recorded in the United States since 1950. This represents a small fraction of the total number of tornadoes, with only 0.57% classified as EF4 or EF5 from 1995 to 2014. The last recorded EF5 tornado occurred in 2013, further emphasizing their infrequency.

However, it is important to acknowledge the limitations of this conclusion. The transition from the Fujita scale to the Enhanced Fujita scale may affect the comparability of historical data, and potential biases in reporting could influence perceptions of tornado frequency. Additionally, while the data is derived from reputable sources, the need for ongoing research into tornado trends and their relationship to climate variables remains critical.

Readers are encouraged to critically evaluate the information presented and consider the nuances surrounding the rarity of EF5 tornadoes, as well as the broader implications of tornado frequency in the context of climate change.