Map of rainfall totals across NWS Paducah's area of responsibility (western Kentucky, southern Illinois, and southeastern Missouri) for the period July 18–19
In a two-day period from July 18 to July 19,2023,significant flooding occurred across western portions of Kentucky,southern Illinois,southeastern Missouri,and northwestern Tennessee caused by stalled heavy thunderstorms which brought high rainfall rates to numerous locations across western Kentucky. The flooding event also inundated locations previously hit by the 2021 Western Kentucky tornado. Numerous homes were flooded across western Kentucky,and several flash flood emergencies were issued for locations in western Kentucky and southern Illinois as well.[1][2]
Showers and thunderstorms developed ahead of a mesoscale convective system along a low-level convergent axis on the afternoon of July 18 across portions of southeast Missouri.[3] Favorable precipitable water values around 1.7-1.9 inches,along with wind shear around 50-60 knots,and most-unstable convective available potential energy (CAPE) in the 2000 values,yielded conditions for the developed thunderstorms to intensify and produce heavy rainfall.[3]
The next day,a moderate risk of excessive rainfall was issued by the Weather Prediction Center,and a flood watch was issued for Kentucky,Illinois,Tennessee,and Missouri.[4] Convection initiated in the vicinity of the Tri-state area in the early morning hours of July 19,and precipitable water values increased from the previous day to 1.8-2.3 inches,and a strong boundary layer moisture convergence from an isentropic ascent,combined with the same CAPE values from the previous day,allowed a strong low level jet and training convection to rapidly increase in coverage across central Missouri and head southeastward along a stationary front,causing heavy rainfall.[5][6][1] Another mesoscale convective system developed several hours later,leading to additional high rates of rainfall.[7] Convection continued to form on the afternoon of July 19 as 850-millibar inflow at 20-30 knots and favorable thermodyamics led to additional rainfall across southeast Missouri,southern Illinois,western Kentucky,and northwest Tennessee.[8]
The Weather Prediction Center's excessive rainfall outlook for July 19.
Near Mayfield,11.28 inches (287mm) of rain fell,setting a new record rainfall in Kentucky.[18][20][6]6.9 inches (180mm) of rainfall fell in Paducah,Kentucky,which was the second—highest daily record there.[6][21] The event was also considered a 1 in a 1,000-year event.[6]
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