Fujita Scale Explained: The Enhanced Fujita Tornado Ratings

From the original F scale to the EF scale

The original Fujita scale classified tornado intensity using observed damage and estimated wind speeds. The Enhanced Fujita, or EF, scale became operational in the United States on February 1, 2007. It revised how surveyors relate damage to estimated winds and incorporated more types of structures and vegetation.

Historical reports may use F ratings, while current U.S. reports generally use EF ratings. The estimated wind ranges are not interchangeable: an F3 in an older record and an EF3 in a newer report use different numerical wind estimates. Read the scale and date associated with the source.

Enhanced Fujita scale chart

The National Weather Service lists EF0 at 65–85 mph, EF1 at 86–110 mph, EF2 at 111–135 mph, EF3 at 136–165 mph, EF4 at 166–200 mph and EF5 above 200 mph. These values represent estimated three-second gusts at the point of damage, rather than a continuous measured wind at every location.

Weather Service materials often group EF0 and EF1 as weak, EF2 and EF3 as strong, and EF4 and EF5 as violent. These are intensity groupings, not statements that a so-called weak tornado is safe. Even an EF0 can injure people and damage property.

How survey teams assign a rating

After a tornado, trained surveyors examine the damage and compare it with recognized damage indicators and degrees of damage. Indicators include different building types, structures and trees. Surveyors consider how the observed damage relates to the likely wind and the construction involved.

The goal is to assign a rating reflecting the highest estimated wind in the surveyed damage path. That rating does not mean every location experienced the same intensity. A home at one point can experience much less or more damage than another building along the track.

Estimated wind is not always measured wind

The EF scale is primarily a damage-based estimate. The presence or absence of well-built structures and other indicators affects what surveyors can assess. A lack of severe observed damage does not automatically prove that no high winds occurred in an area with few suitable indicators.

A radar measurement or an instrument reading may provide additional information, but the published EF rating should be understood according to the agency’s survey and methodology. Do not infer an exact wind at your house simply from the tornado’s overall rating.

The scale is not a forecast

A tornado’s final rating is generally determined after damage is assessed; it is not a way to decide whether to shelter during a warning. Tornadoes can change intensity along their path, and the future rating is not known when someone receives an alert.

When a tornado warning is issued, follow National Weather Service guidance immediately. Go to a basement or a small interior room on the lowest floor of a sturdy building, away from windows. Protect your head and follow local emergency instructions.

Tornado ratings versus hurricane categories

The EF scale describes estimated tornado gusts using damage indicators. The Saffir-Simpson Hurricane Wind Scale classifies hurricanes using maximum sustained wind. The two scales measure different quantities over different time intervals and should not be compared as if their numbers were equivalent.

Neither rating summarizes every danger from a storm. A hurricane category does not measure storm surge or rainfall flooding; an EF rating does not describe the full range of local hazards during a severe thunderstorm. Read the warnings relevant to your location.

Reading a damage report

A published survey may describe the tornado’s track, path width, estimated peak wind and examples of damage. Preliminary information can be revised as more evidence becomes available. Distinguish the survey’s measured or estimated quantities and its limitations.

Avoid making structural or insurance decisions from a rating alone. Have qualified professionals assess the particular building and document visible conditions when it is safe. An intact exterior does not rule out hidden damage, and a damaged structure may be unsafe to enter.

Safety after a tornado

Stay clear of downed power lines, leaking utilities, unstable walls and broken glass. Listen to emergency officials before entering a damaged area or using roads. If water has entered the building, do not approach wet electrical equipment.

Contact emergency services for immediate hazards, notify your insurer when appropriate and preserve reports and photographs. Recovery decisions should follow a site-specific safety assessment rather than the category number printed in a news report.

Types of tornadoes versus EF categories

NOAA describes tornadoes associated with rotating supercell storms and non-supercell tornadoes associated with storm lines or forming landspouts. Waterspouts occur over water. A dust devil is a different phenomenon and is not a tornado. These formation descriptions do not tell you a tornado’s eventual EF rating.

Terms such as rope or wedge describe a visible shape, which can change during the event; appearance alone does not establish wind speed or danger. Some tornadoes have no fully visible condensation funnel. When an alert is issued, seek shelter immediately rather than trying to classify the storm.

Hurricanes and tornadoes: key differences

A hurricane is a large tropical cyclone whose hazards can include storm surge, flooding, destructive winds and tornadoes. A tornado is a much smaller rotating column connected to a storm and the ground. Hurricanes can persist for days; individual tornadoes often last minutes, although duration and size vary.

The Saffir–Simpson scale classifies hurricanes using sustained wind, while the EF scale estimates tornado wind from surveyed damage after an event. Neither scale describes every hazard. Follow evacuation guidance for hurricane surge and flooding, and take immediate sturdy shelter when a tornado warning applies.

Is there an F6 tornado?

There are no official U.S. F6 or EF6 tornado ratings in the operational F0–F5 and EF0–EF5 classifications. Historical theoretical extensions or informal uses of F6 are not official storm ratings; preliminary reports can also change after survey. The six current categories start at EF0, not EF1.

Flying debris and failing buildings are dangerous at any rating. During a warning, shelter immediately in a basement or small interior room on the lowest floor of a sturdy building, away from windows, and protect your head. Never wait for a rating, which is assessed after the event.

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