1920 Palm Sunday Tornado Outbreak - Overview

Overview

According to meteorologist and weather historian Charles Merlin Umpenhour, climatic conditions were favorable on Palm Sunday 1920 for all the atmospheric ingredients to come together needed to create the classic setup needed for long-track tornadoes. However, forecasting, communications technology, and public awareness about Severe Weather was nearly nonexistent in 1920 and would not begin for another 33 years, when the U.S. Weather Bureau would implement its public Watch (the word ‘forecast’ was used until 1966) and Warning program in 1953.

For the residents of the Great Lakes region and Ohio Valley areas, the only source of weather information was the rather vague forecasts that were issued in the local newspaper the day before or by word of mouth. The use of the word "tornado" was strictly prohibited in public weather forecasting until the 1950s because of the fear and panic it might cause. This policy would come under-fire in the years to come especially after the Tri-State Tornado in 1925 that stands today as the deadliest tornado in American history.

Weather forecasters and the public alike in the Chicago, Dayton, Ohio, Fort Wayne, Indiana, Lansing, Michigan, South Bend, Indiana, and Toledo areas were unaware that the stage was set that day for a significant tornado outbreak that would follow a balmy and seemingly tranquil Palm Sunday afternoon. The weather maps in use in March 1920 showed a rather large and deep cyclone over northern Iowa that was forecast to move across central Lower Michigan by nightfall with a trailing cold front. Meteorologists knew rain showers and perhaps a thundershower was a good possibility, but were unaware that the helicity, lifted index, and upper level winds were being guided by a strong jet stream with a probable negative-tilt that would create favorable conditions for the development of tornadoes.