Why do ratings from the original F-scale differ between SPC and others tornado records?
Both original F-scale and the Enhanced F-scale are based on a subjective judgment of damage intensity, but the EF-scale has very specific guidelines for rating an assortment of damage targets. By contrast, the F-scale only specified “well built homes” with all else left to guesswork. Consistency was a major problem as well, because hundreds of people rated tornadoes for Storm Data during the F-scale era. Currently and in recent decades, damage ratings for the “official” database are made by meteorologists at each local forecast office where tornadoes are reported. Sometimes, first-hand damage surveys are done, but because of travel budget constraints, ratings often must be made from spotter, chaser and/or media accounts. In order to assign F-scales to tornadoes from before about 1978 (the year varies from state to state), NSSFC contracted with college students to cross reference the NSSFC file with newspaper articles. When information that conflicted with Storm Data were uncovered, a j
