Fact Sheet - High Winds Across Kentucky
A high wind event is classified as any wind of 50 knots or greater. In the U.S. it is assumed that at 50 knots, the potential for wind damage begins (Doswell 1994). High wind events are often associated with the central United States, specifically the Great Plains. While Kentucky's high wind events may not occur as frequently as those in the Plains, they do occur often enough to be of significance. The Storm Prediction Center provides a historical wind and wind damage archive, in which high winds of 50 knots or greater are recorded. For this project, the total number of high wind events by county was examined from 1983-1994. One might assume that the number of high wind events would decrease as one moved eastward toward the more mountainous regions of Kentucky. However, this research brought about much different results.
The data used were archived and made available on the Internet by the Storm Prediction Center. Because the counties vary greatly in size, it is not always accurate to compare the number of events within each county. To be valid, the data were normalized to the number of wind events per 100 square miles. After the numbers were entered in to the Surfer Map Viewer program, the counties with the most frequent wind events became quite evident. Jefferson, Hardin, Bullitt, Boone, Kenton, Campbell, Fayette, and Boyd counties had a significantly higher frequency of wind events. However, these counties are not all similar in latitude, longitude, or even physiography. What these counties do have in common, though, is their relation to a large city and consequently a larger population. Boone, Kenton, and Campbell counties are all on the outskirts of Cincinnati, whereas Hardin County has Elizabethtown and Fort Knox. Fayette County is home to Lexington, and finally Jefferson County, with the highest number of events, is home to Kentucky's most populous city, Louisville. Not only did Jefferson County report the most wind events, but Louisville has the record non-tornadic wind gust for Kentucky, at 81 miles per hour. By comparing the map of high wind events per 100 square miles (or total wind events per county), with that of population density in Kentucky, one can easily notice the similarities.
High wind events in less densely populated counties may go unreported when they do not produce reportable property damage. It is likely that high winds in larger cities would produce reportable damage. This relationship of reporting to population density accounts for some of the variance among counties. The eastern and western regions of Kentucky have a much lower population density than the central counties straddling I-65 from Jefferson County south to Simpson County. As expected, these counties had a much smaller record of high wind events.
The correlation between population and reported wind events is evident within many of the counties, not just those with a high population. For example, Lawrence County and many surrounding Eastern Kentucky counties have a low population density. That county, along with several other eastern counties has had four or less high wind events reported in the twelve year time period examined. While one could assume this is caused by the higher elevations impeding severe storms, a similar pattern is evident in the lower elevations of the west. Marshall, Calloway, Graves, and several other western counties have low population densities as well as a low frequency of reported high wind events. While the relationship between reported events and population holds true for many counties, it is not the rule. A few Kentucky counties, such as Simpson, have low population, but still have a high occurrence of reported strong wind events. Therefore, these data do not provide a firm basis for comparisons between or among counties.
Doswell, Charles. "Extreme Convective Windstorms: Current Understanding and Research". National Severe Storms Laboratory. Internet. http://www.nssl.noaa.gov/~doswell/barcelona/Barcelona_wind.html (May 24, 2000)
Storm Prediction Center. "Historical Convective Wind and Wind Damage Data". Internet. http://www.spc.noaa.gov/archive/wind/ (May 24, 2000).
U.S. Census Bureau. County Populations for Kentucky. 1990.