On May 20, 2013, a devastating EF5 tornado carved through Moore, Oklahoma. It left 24 people dead, injured hundreds, and caused billions in damage. It also marked the last time an EF5 tornado was officially recorded in the United States.
Today, we mark the 12th anniversary of that storm—and the longest stretch in recorded history without an EF5-rated tornado. Known as the “EF5 drought,” this period has prompted deep scientific reflection, widespread controversy, and a reckoning with the Enhanced Fujita (EF) scale itself.
The EF Scale and Its Limits
The Enhanced Fujita scale, introduced in 2007, is used in the United States and a handful of other nations to estimate tornado intensity based on the damage caused. Ratings are determined by on-the-ground surveys using Damage Indicators (DIs) and Degrees of Damage (DoD) guidelines.
The problem? Damage is a proxy for wind speed—and an imperfect one at that. A tornado may exhibit EF5-level winds but, if it tears through empty farmland or poorly constructed buildings, it may never be rated EF5.
From Moore to Silence
Since the Moore EF5, the National Weather Service has not rated a single tornado EF5, despite multiple events producing wind speeds that qualify.
Some examples include:
- 2013 El Reno Tornado: Initially rated EF5 based on radar-measured wind speeds near 300 mph. Later downgraded to EF3 due to lack of damage indicators.
- 2014 Mayflower–Vilonia, Arkansas: Damage swept clean, but homes lacked proper anchoring. Rated EF4.
- 2021 Western Kentucky Tornado: Destruction was extensive, but building quality issues led to an EF4 rating.
- 2023 Rolling Fork–Silver City Tornado: Estimated winds near EF5 levels, but lacked sufficient structural damage to confirm it.
- 2024 Greenfield, Iowa Tornado: Measured winds exceeded 300 mph. Rated EF4.
Each time, the same pattern: extreme wind speeds, contextual damage, but no EF5 rating.
The Rating Controversies
Numerous experts have raised concerns over the Enhanced Fujita scale:
- Construction Bias: Tornadoes that strike poorly constructed buildings often receive lower ratings.
- Subjectivity: Rating is heavily reliant on interpretation by individual surveyors.
- Wind vs. Damage: Some tornadoes with documented EF5-level wind speeds fail to receive the rating because the wind didn’t hit a robust structure.
Timothy P. Marshall, one of the country’s most renowned tornado damage surveyors, has called several recent events “EF5 candidates.” But a “candidate” is not the same as a designation.
A Statistical Anomaly
In 2025, researchers at the University of Oklahoma and the National Severe Storms Laboratory released a landmark study: the odds of going 11 full years without an EF5 tornado were just 0.3%.
The study questioned the EF scale’s effectiveness and argued that tornado ratings should perhaps reflect total impact rather than wind speed alone. The 2011 Super Outbreak, which included four EF5s, was used as a case in contrast.
EF5 Wind Speeds, EF4 Ratings
According to Doppler data, debris analysis, and damage assessments, many tornadoes over the past 12 years could’ve warranted EF5 ratings:
- 2015 Rochelle–Fairdale, IL: Winds over 200 mph
- 2020 Bassfield–Soso, MS: High-end EF4; possibly EF5
- 2023 Didsbury, Alberta: EF4 damage but wind speeds suggesting EF5
- 2024 Greenfield, Iowa: Doppler measured up to 319 mph
But in each case, either construction flaws or lack of damage indicators led to an EF4 verdict.
International Friction
Outside the U.S., the International Fujita scale (IF) and Doppler radar-based techniques are sometimes used to augment ratings. In Canada, the 2018 Alonsa and 2020 Scarth tornadoes had radar-confirmed EF5-level winds, but were rated EF3 or EF4 due to survey criteria.
The 2021 South Moravia tornado in the Czech Republic was one of the strongest in European history, reaching IF4. Weak construction connections again prevented an IF5 designation.
Has the EF Scale Outlived Its Usefulness?
More scientists and engineers are calling for a modernization—or even replacement—of the EF scale.
- Do we need to incorporate radar data into official ratings?
- Should we focus on wind speed over damage?
- Is a rating system tied to construction standards inherently flawed?
As we face more frequent and extreme weather events, these questions are growing louder.
Conclusion: The Drought Continues
Over 4,000 days have passed without an EF5 tornado in the U.S. That’s more than a decade of storms stopping just short of the highest classification.
But it’s not because the wind has gone silent. It’s because our tools to measure it may no longer be sufficient.
As the U.S. enters another severe weather season, the EF5 drought remains intact—but the conversation around how we rate tornadoes may finally be shifting.
