Fact Sheet - Kentucky's Mean First Snowfall
David Sander Research Assistant and Glen Conner
State Climatologist Emeritus for Kentucky
 
The first snowfall of the winter season is a highly anticipated event throughout Kentucky. The first measurable snowfall of the winter season, though, falls at various times in different areas of the state. Kentucky weather is often sporadic, and it is often difficult to make long-term predictions concerning when or where significant snow will fall. For this reason, a map showing the first measurable snowfalls of a winter season is helpful.

A measurable snowfall is defined as 0.1 inch or greater. Using data collected from the Midwestern Climate Center, all measurable snowfall events from 1996-1996 were collected for twenty-eight Kentucky stations from the state's four climatic divisions. The first snowfall of each winter season was then extracted from the data, and the mean first snow event was taken for each station. The thirty year mean first snowfall was entered into the Surfer mapping program. With the mapping program, a contour map was created showing the average date of the first measurable snowfalls throughout the state.

The final map shows a clear distribution of the first measurable snowfall days across the state. For example, eastern regions of the state saw a much earlier winter snowfall on average than the western regions. Likewise, the more northern portions of the state had an earlier first snowfall date than the southern areas. Of all the stations examined, Covington, located in the far northern part of Kentucky, had the earliest average "first of the season" snowfall. Its mean date was November 20th. Elkton, located in a more southwestern part of Kentucky averaged the latest first snowfall on December 29th. The overall average first snowfall date of all stations examined was December 16th. For the most part, the southern half of the state saw snowfalls after mid-December, while the northern half saw the first snow before the middle of December.

For many individual stations, the first snow event of the year varied for as much as three months. The average snowfall dates between stations, however, varied by just over a month. Variance of the thirty-year mean around the state was significantly less than yearly variance for a particular station. No well-defined patterns of variability were evident, but the west seemed to show a greater variability between winter seasons than the eastern regions of the state. The farther west and south one traveled in the state, the more random the first winter snowfall is likely to be.

With a map of the average first measurable snowfalls in Kentucky, one can now have some idea of when and where the first snows may fall throughout the state with the coming of each winter season. The map confirms what many would have expected from the winter season in Kentucky. Earlier first snows are common in the Northern regions and in the mountainous Eastern regions of the state, just as later average first snows are common in the southwestern areas of Kentucky. While past data is a good indicator of future snowfall events, the state's snowfall is still quite random wherever one may be in the state.

REFERENCES:
Climatological Data. Kentucky. July 1992: NOAA. Vol. 87 No. 7.
Climatological Data. Kentucky. July 1995: NOAA. Vol. 90 No. 7.
Midwestern Climate Center. University of Illinois: Champaign.
Surfer for Windows. Golden Software, Inc. 1994.