In my experience with historic newspapers, it seems that "tornado" wasn't a word used fairly universally until the latter half of the 20th century. Some newspapers would refer to them as "storms," "winds," or (quite commonly) "cyclones."

Perhaps this has something to do with the fact that there was a policy in place at the Weather Bureau (forerunner to today's National Weather Service) that banned the use of the word "tornado" in any of their official products until 1950. It was feared that use of the word could create a mass panic. Only after the ban's lifting were tornado warnings broadcast.
The fact that they believed that the word alone could cause panic seems to indicate that there was some general understanding of what a tornado was; however, the ban means that they were probably not discussed in the media quite as plainly. So, I would argue that this date marked a significant turn in the public's knowledge about tornadoes.