The Enhanced Fujita Scale: How meteorologists categorize tornadoes

ROCHESTER, N.Y. (WROC) — On July 10, 2024, the National Weather Service (NWS) in Buffalo issued 18 tornado warnings for parts of Western New York. Prior to that, the greatest number of tornado warnings issued in a single day was 7, back on June 2, 1998. As of today, there were 7 tornadoes confirmed from July 10, ranking as either an EF0 or EF1 tornado. Have you ever wondered how tornadoes are classified or what EF stands for? Let’s break it down.

Tornadoes can occur in all different shapes and sizes ranging from a few yards to over one mile in width. However, according to the NWS, “the shape and size of a tornado does not necessarily say anything about the tornado’s strength or it’s capability to inflict damage.” In fact, unlike hurricanes, which can be categorized before making landfall, tornadoes cannot be categorized until the damage caused is assessed.

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The Enhanced Fujita Scale or EF Scale is the method used to assign a tornado a ‘rating’ based on estimated wind speeds and related damage, according to the NWS. This scale become operational on February 1, 2007. Prior to this date, the original Fujita Scale was used to categorize tornadoes. According to the NWS, the EF Scale was revised from the original Fujita Scale to reflect better examinations of tornado damage surveys so as to align wind speeds more closely with associated strong damage. The new EF Scale now has more to do with how structures are designed and built. Below is the EF Scale ratings and wind speeds associated with the rating:

The EF Scale winds are derived from engineering guidelines but are still only judgmental estimates. This is because:

• Nobody actually knows the “true” wind speeds at ground level in most tornadoes, and
• The amount of wind needed to do similar-looking damage can vary greatly, even from block to block or building to building, based on how they are built.

It is not only wind speeds that categorize tornadoes; it’s also the amount damage that is caused by the tornado. The photos below explain some of the damages that can be seen with each EF Scale category:

Click here to learn more about the EF Scale.

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