(WKBN) — Despite the wintry conditions this morning, the first day of spring is tomorrow and that means severe weather season is right around the corner.

Ohio severe weather awareness week starts today and will last through Saturday. During this week, the Storm Team 27 weather team will inform you of important information that will assist you in the event of severe thunderstorms.

Arguably the most destructive type of severe weather is tornadoes. Therefore, it is important to understand how the intensity of tornadoes is measured by meteorologists.

The Fujita scale was invented in 1971 by Dr. Ted Fujita in collaboration with Allen Pearson from the Storm Prediction Center and was used to rate tornadoes until 2007. This scale had categories F0-F5 with 0 being a weak tornado and 5 being a significant tornado. The original categories were: F0 (40-72 mph winds), F1 (73-112 mph winds), F2 (113-157 mph winds), F3 (158-206 mph winds), F4 (207-260 mph) and F5 (261-318 mph).

However, in 2007, this scale was decommissioned in favor of the Enhanced Fujita (EF) scale. Now, the EF scale is used to measure the damage and intensity of tornadoes. The original Fujita scale overestimated the winds necessary to cause certain types of damage.

The EF scale is an improvement over the original scale because it accounts for the integrity of structures and defines what winds cause structural failure. Basically, the EF scale better aligns wind speeds from a tornado with the damage from the storm itself.

Enhanced Fujita scale vs. the original Fujita scale. Image courtesy of NOAA.

History of Ted Fujita and the Fujita scale

Dr. Ted Fujita is one of the most influential meteorologists of all time and his story is eventful. Dr. Fujita was born in Japan in the year 1920 and was attending undergraduate school during World War II. During the war, he was living in the town of Kokura, Japan which was the original target city for the “Fat Man” plutonium bomb.

However, smoke from a nearby city caused the United States to pick their secondary target: Nagasaki. Dr. Fujita studied the blast patterns and damage caused by the atomic weapons and this research assisted in his development of the original Fujita scale. He would then go on to attend the University of Tokyo where he would earn his doctorate degree. Dr. Fujita was then invited to work at the University of Chicago where he developed the Fujita Scale.

Most people know the Fujita scale goes from F0-F5, but did you know that the original Fujita scale actually had 13 categories? He designed the scale this way to connect it to the Beaufort Scale (old scale used for hurricanes) and the Mach Scale (used for speed of sound).

However, he only intended that the scale go from F1-F5 for tornadic activity with F0 accounting for winds weaker than that of a hurricane. Fujita did, however, include an F6 category for what he considered to be an “inconceivable tornado”. Ohio actually has some experience with this category, but more on that later…

Not only was Fujita a brilliant scientist, but he was also a fantastic artist. He would travel to the United States after tornado outbreaks and produce artistical and complex drawings of tornado paths. Below is an example of his drawing of the Grand Island, Nebraska tornadoes of June 3, 1980.

Drawing of the Grand Island, Nebraska tornadoes on June 3, 1980 by Dr. Ted Fujita. Image courtesy of NOAA.

The F6 tornado of Xenia, Ohio in 1974

Previously, I mentioned that Dr. Fujita made an F6 category for what he considered to be an “inconceivable tornado.” Well, on April 3, 1974 the inconceivable happened when one of the strongest tornadoes ever recorded destroyed the town of Xenia, Ohio.

Picture of the tornado that hit Xenia, Ohio on April 3, 1974. Image courtesy of the National Weather Service.

Dr. Fujita analyzed the damage of many tornadoes from what would become known as the “Super Outbreak of April 3-4 1974” including the tornado that hit Xenia. After viewing the aerial photos of the storm damage in Xenia, Fujita officially rated the tornado as an F6. This was the second and last time that a tornado was rated as an F6. The other F6 tornado occurred in Lubbock, Texas in 1970. However, both tornadoes were officially downgraded to F5 by the National Weather Service.

Aerial damage photo from Xenia, Ohio after the F5 tornado hit the town. Image courtesy of the National Weather Service.

May 31st, 1985 Tornado Outbreak

The Valley is no stranger to intense tornadoes. On May 31, 1985, an F5 tornado devastated the towns of Newton Falls and Niles, OH and many other communities in Trumbull and Mercer counties.

Video of F5 tornado that affected Trumbull and Mercer counties on May 31, 1985.

This tornado was on the ground for 41 miles and was responsible for numerous fatalities. The tornado outbreak on May 31 included 41 tornadoes in Canada and the United States — 21 of which occurred in northeast Ohio and western Pennsylvania. This outbreak is still the deadliest tornado outbreak in Pennsylvania history.