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The Enhanced Fujita Scale: How tornado assessments have evolved

An EF-0 has winds of 65 to 85 mph. The weakest ranking for a tornado typically brings only minor damage. This can include damage to chimneys, broken branches, shallow-rooted trees pushed over, and damage to sign boards.
An EF-1 has winds of 86 to 110 mph. This rating produces moderate damage. Roof surfaces can be peeled away, mobile homes may get pushed off of their foundations or overturned, and moving automobiles can get blown off roads.
An EF-2 tornado contains a 3-second wind gust of 111 to 135 mph. This designation is considered to be significant, as it can cause considerable damage. An EF-2 can lead to roofs being torn off of frame houses, mobile homes being demolished, overturned boxcars, large trees snapped or uprooted, the generation of light-object projectiles, and cars being lifted off the ground.
An EF-3 is considered to be a severe tornado, with winds of 136 to 165 mph. Roofs and some walls can be torn off of even well-constructed houses, trains can become overturned, the uprooting of most trees in forests, and heavy cars being lifted off the ground and thrown.
Described as a devastating tornado, an EF-4 possesses winds of 166 to 200 mph. Damage often includes the complete leveling of well-constructed homes, structures with weak foundations blown away some distance, and the generation of large missiles in the form of thrown vehicles.
An EF-5 is the most rare of tornadoes, but it can do catastrophic damage at over 200 MPH. Strong frame houses can become leveled off foundations and swept away, automobile-sized missiles can be thrown in excess of 100 yards, trees can become debarked. Other incredible phenomena has been noted where EF-5 tornadoes rip through.

ROCKFORD (WREX) — Tornadoes can cause a great deal of destruction in a very short amount of time. The rating of tornadoes isn't solely based on wind speed, but the damage they cause.

The original Fujita Scale:

In 1971, Dr. Ted Fujita introduced the F-scale in collaboration with his peers at the University of Chicago. The ratings ranged from F-0 to F-5, with damage ranging from broken tree limbs to houses completely removed from foundations.

The rating of any tornado is based on the most severe damage to well-built structures. Through the years, research and discoveries have allowed for an updated version of the original Fujita Scale developed nearly 50 years ago.

Enhanced Fujita Scale:

The original Fujita Scale was decommissioned in 2007. The basic concept of the Enhanced Fujita Scale is the same as the original Fujita Scale developed in the early 1970s. The primary difference between the F-Scale and the EF-Scale is that it takes into account quality of construction and standardizes a different variety of structures.

The noticeable difference between the Fujita Scale and the Enhanced Fujita Scale is the wind speed changes, particularly regarding stronger tornadoes. It was discovered that more catastrophic damage can be done with lesser winds. For example, the original F-Scale put wind speeds of F-5 tornadoes at between 261 and 318 mph. The EF-Scale ranks any tornado with winds of 201 mph or more as an EF-5. The wind speeds of both F-Scale and the newer EF-Scale are based on three second gusts.

Other goals of the Enhanced Fujita Scale include data collection. Tornadoes are both well-documented, yet somewhat mysterious. The revised version of the Fujita Scale includes additional data which could provide huge insight into the inner-working of tornadoes. Survey crews are expected to collect the mean and maximum damage path width, a basis for damage assignment, latitude and longitudes of the start and end point, number of hours spend on the damage survey, and the names of the survey team members.

Survey crews go through a 28-point checklist to determine what type of damage occurs to a specific location along the tornado path. From that checklist, a rating can be given to a tornado at a point. As a reminder, a tornado can be assigned more than one rating along the entire path length. What typically gets reported is the highest rating assigned to the tornado at its most severe.

Justin Ballard

Justin Ballard joined 13 WREX as the weekday morning meteorologist. He’s a proud graduate of UNC-Charlotte and happy to call Rockford home.

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