Thunderstorms with heavy rainfall occurred during the peak heating hours late in the afternoon. The storms formed in a very moist but weak southwest wind flow at the surface and aloft.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS PAH wrote it up.
Thunderstorms with heavy rainfall occurred during the peak heating hours late in the afternoon. The storms formed in a very moist but weak southwest wind flow at the surface and aloft. A weak 500 mb shortwave over the lower Ohio Valley contributed to the generation of the storms.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Paducah, KY wrote its last area forecast discussion before the first event at Aug 18, 2:23 PM CST, 3 hours 7 minutes earlier.
Area Forecast Discussion National Weather Service Paducah KY 323 PM CDT Wed Aug 18 2021 .SHORT TERM...(Tonight through Friday night) Issued at 321 PM CDT Wed Aug 18 2021 Convective activity, especially across west Kentucky, was a little more prominent than anticipated by some of the CAM guidance, but was suggested by the deterministic Canadian/European short and medium range guidance. The upper forcing and zone of enhanced vorticity along the eastern side of the positively tilted trough (just north of the WFO PAH forecast area) is aiding in the development of showers and thunderstorms across southern sections of the Purchase/Pennyrile region of west Kentucky this afternoon. SPC still has a marginal risk for severe thunderstorms (mainly damaging wind potential) across this area, but any strong/severe threat should diminish quickly by late this afternoon/early evening. With the main upper trough axis and forcing moving through the area this evening and overnight, reduced the rain chances significantly west of the Ohio River overnight. Given the lack of significant evaporation and mixing, introduced patchy/areas of fog back across the area overnight. For Thursday, an approaching low and middle level amplitude ridge/shear axis to the west, vorticity lobes rotating around the broad southwest to northeast trough axis aloft, deeper moisture to the south and east, and calm to weak divergent surface flow at the surface will also serve to create a less than ideal set up for widespread rain chances. Given the relatively stable boundary layer set up in the morning (fog development overnight), it will take more focused lift and boundary interaction to generate updrafts sufficient for more than widely scattered to scattered convection Thursday. Kept the best chances for rain along the ridge shear axis over southeast MO and across the eastern Pennyrile ahead of the focused lift ahead of the trough. By Thursday night, ridging aloft and weak flow at the surface will mitigate any widespread precipitation development along a diffuse boundary setting up over southeast MO and western KY. With the ridge axis moving over the WFO PAH forecast area early on Friday, agree with my western NWS offices in reducing rain chances during the morning hours until the better forcing and lift comes into play Friday afternoon and evening. However, the ridge remains relatively strong Friday evening, mitigating any meaningful chances for rain Friday evening. By the midnight hour, the forcing increases enough to generate a better chance for rain by Saturday morning. .LONG TERM...(Saturday through Wednesday) Issued at |321 PM CDT Wed Aug 18 2021 The main theme this weekend into early next week will be a strengthening upper-level ridge centered over the south central states. This building ridge will bring a surge of late summer heat, along with much lower chances of convection. Elevated rain chances will gradually diminish over the weekend. The models have trended a little slower and stronger with an upper-level low, which is forecast to stall briefly over the upper Ohio Valley Saturday. This upper low is now forecast to capture Tropical Storm Henri and bring it closer to the East Coast. Although this will have no practical implications for our weather, it may delay the timing of the upper-level ridge over our area. Highs Saturday will be mainly in the upper 80s, with a good chance of more showers and storms. Later in the weekend, a weakening cold front is forecast to move east-southeast across our region. There will be very little upper- level support for precipitation. However, given the weak surface trough and lack of a strong ridge aloft, will maintain low chance pops in the forecast for Sunday. The front will have no practical effect on our weather, other than a brief wind shift to northwest and a slight lowering of dew points into the lower 70s Sunday. Monday through Wednesday, the 500 mb high will expand and broaden across much of the southern two-thirds of the nation. This will allow heat to return. Daily highs will be in the lower 90s, with overnight lows in the lower 70s. Generally rain-free conditions are expected, however there is some model variability on Wednesday. A surface cold front could sag far enough south to justify slight chance pops for Wednesday. && .AVIATION... Issued at 1258 PM CDT Wed Aug 18 2021 For the WFO PAH 18z Wednesday WFO PAH TAF issuance, a disturbance running along the lower and middle Mississippi Valley region will produce mainly VFR ceilings today and through the midnight hour. Did add a mention of vicinity thunderstorms to all except the KMVN TAF site, even though the probability may be less near KEVV. Given the recent lightning strikes to the north earlier this morning north of KEVV, decided to keep a mention of thunderstorms in. Overnight, introduced MVFR visibilities and VFR ceilings over the TAF sites. With a frontal boundary nearby in southeast Missouri and west Kentucky, also added IFR ceilings in the 10z-13z Thursday time frame. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && SHORT TERM...Smith LONG TERM...MY AVIATION...Smith
Hazardous Weather Outlook National Weather Service Paducah KY 335 PM CDT Wed Aug 18 2021 ILZ075>078-080>094-INZ081-082-085>088-KYZ001>022-MOZ076-086-087- 100-107>112-114-191000- Jefferson-Wayne IL-Edwards-Wabash-Perry IL-Franklin-Hamilton- White-Jackson-Williamson-Saline-Gallatin-Union-Johnson-Pope- Hardin-Alexander-Pulaski-Massac-Gibson-Pike-Posey-Vanderburgh- Warrick-Spencer-Fulton-Hickman-Carlisle-Ballard-McCracken-Graves- Livingston-Marshall-Calloway-Crittenden-Lyon-Trigg-Caldwell- Union KY-Webster-Hopkins-Christian-Henderson-Daviess-McLean- Muhlenberg-Todd-Perry MO-Bollinger-Cape Girardeau-Wayne MO-Carter- Ripley-Butler-Stoddard-Scott-Mississippi-New Madrid- 335 PM CDT Wed Aug 18 2021 This Hazardous Weather Outlook is for portions of southern Illinois, southwest Indiana, western Kentucky, and southeast Missouri. .DAY ONE...This Afternoon and Tonight A marginal risk of severe storms remains for the remainder of this afternoon and early evening, mainly across parts of southwest Kentucky. Damaging winds will be the main severe weather hazard, while heavy rain and lightning will be more commonplace with the storms. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday Almost daily storm chances will be highest during the peak heating hours of the afternoon and early evening, especially Thursday through Saturday. Storm chances gradually diminish thereafter. Locally heavy rain and lightning will be the main hazards. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated at this time, but a basic weather watch is still appreciated. Smith
The national radar mosaic for the moment the first event began.
1 flood. Local standard time, as filed.
Water was over State Route 1831, a lightly travelled road near State Route 405. Water was also over a couple of lightly travelled county roads east and northeast of Utica.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Kentucky in 2021Every state in 2021This day in weather historyWarnings in Kentucky, August 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 971620.