Tornadoes are among Earth’s most powerful and destructive natural phenomena. These rotating columns of air vary significantly in their intensity and physical dimensions. Understanding these events is important for comprehending their potential impact.
Understanding the Enhanced Fujita Scale
Tornadoes are classified using the Enhanced Fujita (EF) Scale, which assesses intensity based on damage. This scale ranges from EF0 to EF5, with EF5 as the highest rating. The EF Scale, which became operational in the United States on February 1, 2007, updated the original Fujita Scale to more accurately correlate observed damage with estimated wind speeds.
When a tornado strikes, trained personnel survey the damage and compare it to a list of “Damage Indicators” (DIs) and “Degrees of Damage” (DoD). This process helps to estimate wind speeds. The EF Scale uses 28 different damage indicators, accounting for factors like construction quality and building types. For instance, an EF0 tornado has estimated wind speeds between 65-85 mph, causing light damage like stripped roof shingles, while an EF5 signifies incredible damage. The EF Scale provides estimated wind speeds in 3-second gusts at the point of damage, recognizing these are estimates rather than direct measurements.
Defining the Physical Scale of an EF5 Tornado
An EF5 tornado represents the pinnacle of tornado intensity, characterized by extreme wind speeds and significant physical dimensions. Estimated EF5 wind speeds exceed 200 miles per hour (322 kilometers per hour). While the original F5 rating had a wind speed range of 261-318 mph, EF5 classification recognizes winds over 200 mph cause extreme damage.
The width of an EF5 tornado can vary considerably, but they are often very large. While the average tornado is about 50 yards (46 meters) wide, EF5s can range from hundreds of yards to over a mile in width. Some of the widest tornadoes on record, though not all rated EF5, have reached widths of 2.5 to 2.6 miles (4.0 to 4.2 kilometers).
The path length of an EF5 can also be extensive, traveling for many miles, potentially dozens. For strong to violent tornadoes (EF2-EF5), the average path length is about 23.9 kilometers (14.9 miles), and for the strongest F5 tornadoes, path lengths can exceed 50 kilometers. Its scale combines devastating wind speeds, substantial width, and extended track length.
The Destructive Impact of an EF5 Tornado
The destructive power of an EF5 tornado is immense, leaving catastrophic damage. At this intensity, well-built and well-anchored homes are often swept cleanly off their foundations, leaving only bare concrete slabs. Structures are pulverized; large, steel-reinforced buildings, like schools, can be completely leveled.
Vegetation suffers extreme destruction; trees are debarked, snapped off, or entirely uprooted. Low-lying grass and vegetation can be shredded. Vehicles become projectiles, shredded and thrown for miles. The impact zone often becomes unrecognizable, demonstrating immense destructive power.
Rarity and Significance of EF5 Tornadoes
EF5 tornadoes are exceptionally rare events, a tiny fraction of all tornadoes globally. Historically, F5/EF5 tornadoes comprise a minuscule 0.1% of all recorded twisters. Between the EF Scale’s 2007 operational date and 2017, only nine confirmed EF5 tornadoes occurred in the United States.
Their extreme rarity underscores their significance. While many tornadoes can cause substantial damage, EF5s are statistical outliers, requiring extreme atmospheric conditions and specific damage indicators for their top rating. Despite their infrequency, EF5 tornadoes cause a disproportionately high number of fatalities and extensive destruction, highlighting their devastating power.