May 11 • 1953 — What was already a costly season became far worse this afternoon when a tornado touched down SW of Lorena, McLennan Co, TX. It proceeded to move NE, sideswiping Hewitt, then plowing directly through downtown Waco. Hundreds of homes were ddamaged or destroyed, and hundreds of buildings were flattened in the downtown area, around Austin Avenue in particular. About 30 people died in one building — the R.T. Dennis Furniture Co. building — alone, as it was (by eyewitness accounts) twisted, then collapsed, probably because it was not made of steel-reinfoced concrete that might have held a little better to such stresses. 114 people were killed, the second-to-last single tornado to kill more than 100 people in the U.S. so far. It was rated F5; about two hours before this event, an F4 ripped through western San Angelo, destroying about 300 homes and damaging the Lake View School, where students crouched in the hallways as the roof blew off. Remarkably, less than 10 were injured there, but the tornado killed 11 and injured about 200 elsewhere.
• 1970 — An F5 tornado touched down on central Lubbock, TX, and moved generally N, devaststing neighborhoods as it went. 28 people were killed. Though its losses were severe, this tornado is more significant for the advances it made to tornado science. Professor Tetsuya Theodore Fujita of the University of Chicago made a detailed damage survey of this tornado's damage path, and from it:
—He refined the concept of multiple vortices later in the year — he realized that these could be little dust-devil-like vortices, and he now called the "suction spots." The next year, he would publish a paper with the entire concept, now "multiple suction vortices," mapped out.
—He conceived the Fujita wind damage scale. All the original examples of damage for each level on the Fujita scale were taken from the damage at Lubbock.* This, he felt, would be an easier way of caategorizing tornadoes and compiling a database of them. Allen Pearson, then director of the NSSFC, aggreed, and contributed classifications for path width and length that could also be used in a database — this was mainly because of the constraints of keeping records by punch-cards, and when they were phased out, so too were Pearson's components, because it was now easier to add the raw data for their categories.
*The originals can be seen in A.B.C. Whipple's Storm (Alexandria, VA: Time-Life Books, 1982). The examples published in Storm Data (this version is reprinted in Significant Tornadoes) use damage from Lubbock for F0–3, damage from Jordan, IA (6/13/1976) for F4, and damage at Birmingham, AL (4/4/1977) for F5.
