Biology

11 Kentucky Mesonet at WKU stations recorded 15+ inches of rain in July 2016, well above normal statewide average of 4.43

State climatologist Stuart Foster spent his day Tuesday (Aug. 2) traveling across western Kentucky to get a closer look at the impact of July’s record-breaking rainfall.

State climatologist Stuart Foster toured areas of western Kentucky on Aug. 2 to document the impact of July’s record-breaking rainfall. While the extent of crop loss will not be known until harvest, flash flooding and ponding of water has damaged some crops like tobacco fields in Trigg County (top left) and near the Todd-Christian county line (top right). Pastures and other crops, like a soybean field in Caldwell County (above), have benefited from the rainfall. (Photos by Dr. Stuart Foster)

The statewide average for July rainfall is 4.43 inches, but nearly two dozen Kentucky Mesonet at WKU stations recorded more than 10 inches of rainfall in July (including 11 sites with more than 15 inches) and the preliminary Mesonet average was 9.69 inches, said Dr. Foster, who is director of the Mesonet and the Kentucky Climate Center at WKU. The Mesonet has 66 stations in 65 counties.

Mesonet sites recording the most rainfall in July were: Christian County, 18.26; Calloway County, 17.06; Logan County, 16.90; Hopkins County, 16.38; Marshall County, 16.25; Butler County, 16.05; Crittenden County, 15.87; Trigg County, 15.76; Ohio County, 15.75; Todd County, 15.68; and Muhlenberg County, 15.60. Similar totals were recorded at stations that are part of the National Weather Service Cooperative Observer Network.

“We are still analyzing data, but one thing is clear, rainfall totals for July 2016 shattered records at numerous locations,” he said.

For example, the cooperative observer station at Murray, which opened in 1926, recorded 18.43 inches, breaking the previous record by more than 7 inches. Interestingly, many of the records that were broken had been set in 2015.

The weather pattern for July was characterized by many periods of unsettled weather. High humidity and soil moisture, coupled with the lack of a strong jet stream over the region, contributed to the repeated development of slow-moving thunderstorms that dumped copious amounts of rain.

“In most years, a given location in western Kentucky does not record a single day in July with a total rainfall exceeding 2 inches,” Dr. Foster said. “On average, such an event occurs about once every four or five years. In 2016, many locations received 2 inches or more of rain on four different days of the month, more than in any July on record.

“While this marked the second consecutive July that produced record-breaking precipitation, this is an event that we probably won’t see again in our lifetime,” he said. “Given concerns about projections of a changing climate, however, it’s important not just to look at the data showing how much rain fell but to document the impact of that rain and what it meant for the communities and areas that experienced that rainfall.”

Critically, given the time of year and the location of the heaviest rainfall, widespread river flooding did not occur. Instead, the heavy rain caused flash flooding that damaged roads and crops in several counties. While the extent of crop loss will not be known until harvest, ponding of water in low-lying areas and on poorly drained soils will reduce yields. In upland areas, crops, including tobacco, planted on sloping fields were vulnerable to being washed out. But during his trip across the region, Dr. Foster noted that corn, soybeans and pastures in many areas are benefiting from the above-average July rainfall.

Talking with farmers and local officials to document the impact from July’s record rainfall is important as the region experiences more extreme climate and weather events, Dr. Foster said.

“We’ve seen some extreme fluctuations in climate conditions for Kentucky in the past decade,” he said. “The ability of things to swing back and forth is evidenced by looking at 2011 and 2012.”

In Kentucky, 2011 was the wettest year on record (statewide average of 64.34 inches) with heavy rains in April and May causing major flooding along the lower Ohio River, he said.

“Then one year later in 2012 we had record warmth in March followed by intense heat and drought concentrated in the western part of the state,” Dr. Foster said. “We went from extreme wet to extreme drought within a year.”

Does that mean 2017 will be a dry year? It’s too early to tell, he said.

“Many of our recent droughts in Kentucky have occurred during La Niña events. As the strong El Niño of last winter has waned, the outlook is for La Niña conditions to develop into the fall and winter,” he said. “However, the uncertainty of this outlook from the Climate Predication Center has increased over the past several weeks.”

Kentucky Mesonet at WKU stations with July 2016
precipitation totals of more than 10 inches

            County  Total   

• Christian 18.26
• Calloway 17.06
• Logan 16.90
• Hopkins 16.38
• Marshall 16.25
• Butler 16.05
• Crittenden 15.87
• Trigg 15.76
• Ohio 15.75
• Todd 15.68
• Muhlenberg 15.60
• Barren 14.87
• McLean 14.24
• Caldwell 13.62
• Simpson 12.02
• Warren 11.74
• Marion 11.68
• Adair 11.22
• Campbell 10.92
• Henderson 10.57
• Casey 10.51
• LaRue 10.48
• Union 10.32

About the Kentucky Mesonet at WKU: State Climatologist Stuart Foster is director of the Kentucky Mesonet at WKU and the Kentucky Climate Center. Dr. Rezaul Mahmood, professor of Geography and Geology, is associate director of the Mesonet and the Kentucky Climate Center. The project was initially funded with a $2.9 million federal grant for the Kentucky Climate Center, part of WKU’s Applied Research and Technology Program. The first station was installed at the WKU Farm in May 2007. The Mesonet’s statewide network includes stations in Adair, Allen, Barren, Bath, Boone, Breathitt, Breckinridge, Bullitt, Butler, Caldwell, Calloway, Campbell, Carroll, Casey, Christian, Clark, Clinton, Crittenden, Cumberland, Fayette, Franklin, Fulton, Graves, Grayson, Hardin, Harlan, Harrison, Hart, Henderson, Hopkins, Jackson, Johnson, Knott, Knox, LaRue, Lawrence, Letcher, Lewis, Lincoln, Logan, Madison, Marion, Marshall, Mason, McLean, McCreary, Meade, Mercer, Metcalfe, Morgan, Muhlenberg, Nicholas, Ohio, Oldham, Owen, Owsley, Pike, Rowan, Shelby, Simpson, Taylor, Todd, Trigg, Union and Warren counties.

Contact: Stuart Foster, (270) 745-5983