Revisiting tornado watch #211 - a spatial analysis of the May 31, 1985 tornadoes using present-day data for the state of Pennsylvania

On the evening of 31 May 1985, a devastating and deadly tornado outbreak impacted Ohio, Pennsylvania, New York, and Ontario, Canada. A total of 41 tornadoes occurred resulting in 88 fatalities: the deadliest tornado outbreak of the 1980s. Pennsylvania experienced the greatest number of tornadoes with 21 affecting the Commonwealth, causing 65 fatalities. Despite its severity, Pennsylvania’s deadliest tornado outbreak has not been spatially analyzed in academic literature. With the outbreak occurring nearly 40 years ago, one must consider the potential impacts today in comparison to the 1985 time-period. Has the natural and built landscape changed to the extent that the population would be further impacted both directly and indirectly? To assist in answering this question, this study performs a Geographic Information System (GIS) analysis of Pennsylvania’s historical and present-day land cover, census, and building data in locations impacted by the 1985 tornadoes. Data between the two time periods is compared and analyzed to quantify changes since 1985 to estimate if the impacts would be lesser or greater in relation to the expanding bull’s eye effect. This includes estimating the number of fatalities that would occur in the present-day.