Surface high pressure was sitting over the Lower Ohio Valley, but as an upper shortwave and trough passed overhead, it provided the forcing to drive slow moving efficient rainfall. This produced a couple reports of isolated flooding over the two day period.
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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 LMK wrote it up.
Surface high pressure was sitting over the Lower Ohio Valley, but as an upper shortwave and trough passed overhead, it provided the forcing to drive slow moving efficient rainfall. This produced a couple reports of isolated flooding over the two day period.
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 Louisville, KY wrote its last area forecast discussion before the first event at Aug 18, 1:01 PM CST, 2 hours 34 minutes earlier.
Area Forecast Discussion National Weather Service Louisville KY 301 PM EDT Wed Aug 18 2021 .Short Term...(This evening through Thursday) Issued at 248 PM EDT Wed Aug 18 2021 Tonight our region will be situated near the entrance of an upper jet streaming from the Midwest to the St Lawrence Seaway while a 500mb vort max moves into the Ohio Valley ahead of the base of an upper shortwave trough extending from the Great Lakes to the middle Mississippi Valley. Southern Indiana/central Kentucky are also expected to be on the nose of a weak 850mb jet from Arkansas to the Pennyrile. These factors will interact with precipitable water amounts of 2-2.2", K index in the mid 30s, deep warm cloud depths, and some weak isentropic lift, resulting in increasing likelihood of rain, especially after midnight and into Thursday morning. Enough instability will be present for some embedded surface-based thunderstorms. Though there will be a broad east-west surface trough to our north, it will be weakening through the night and the regional surface pressure pattern will be rather flat, leading to little if any wind (outside of thunderstorms). In the moist, stagnant atmosphere some patchy fog may develop early Thursday morning. Shower and thunderstorm coverage should decrease Thursday afternoon as the upper wave moves off to the east and we lose moisture, especially in the mid and upper levels. Muggy lows tonight should be around 70. High temperatures tomorrow are tricky since they will depend on shower coverage and how much sun we'll be able to realize in the afternoon. For now will go with readings generally in the 80-85 degree range (with some spots in the east remaining in the 70s), which is about five degrees cooler than normal. && .Long Term...(Thursday night through Wednesday) Issued at 259 PM EDT Wed Aug 18 2021 Thursday Night - Friday Night... Upper level shortwave trof axis shifts east of the forecast area Thursday night, and drier air in the mid levels wraps in behind it via northwest flow. The upper low pivots southeast over Ohio on Friday, with mid-level vorticity lobes rotating around it. PWATs will be at a relative minimum during this time frame, around 1.1-1.4 inches. Compared to Thursday, conditions should dry out a fair amount Thursday night with only isolated activity possible into the early morning hours of Friday. Cyclonic flow aloft and associated weak ascent in conjunction with diurnal heating could result in isolated to widely scattered showers and perhaps a storm or two Friday afternoon. Instability looks weak to modest with weak flow aloft, so strong storms are not expected. Expect morning lows in the mid 60s to lower 70s with afternoon highs in the mid 80s. Saturday - Sunday... A strong storm system will lift northeast from Minnesota into Ontario on Saturday, and its trailing cold front will approach the region from the west. Though there is a deep, somewhat narrow plume of moisture ahead of the boundary, a building southern CONUS ridge will likely suppress vertical motion aloft. Think there is potential for scattered showers and storms Saturday afternoon and evening. Highs are likely to reach the mid 80s to upper 80s in a few spots. Lingering remnant frontal boundary may spark isolated to widely scattered convection Sunday afternoon. The mid and upper level ridge over the region will continue to strengthen, centered just off to the southwest over the Lower MS Valley. Expect hot, humid conditions with highs in the mid 80s to around 90. Heat indices could start pushing into the mid/upper 90s by Sunday afternoon. Monday - Tuesday... Robust upper level ridge will continue to influence the weather into early next week. Hot, humid summer weather is expected and generally drier. The ridge is forecast to retrograde westward over the southern Plains by Tuesday. There is at least a low-end chance for convection Tuesday, with likely increasing chances later next week. && .Aviation...(18Z TAF Issuance) Issued at 135 PM EDT Wed Aug 18 2021 IMPACTS: -Thunder at/near BWG -MVFR vsbys/cigs Thursday morning DISCUSSION: An upper wave moving northeastward out of the Ozarks will bring showers and storms to the Tennessee Valley this afternoon and evening, affecting primarily BWG. After a brief respite this evening, additional showers and embedded thunder will move through the entire region late tonight into Thursday morning as the upper wave advances into the Ohio Valley. This late night/early morning activity is expected to bring MVFR conditions. CONFIDENCE: Highest confidence is with wind speed/direction. Lowest confidence is with morning visibilities. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && Short Term...13 Long Term...EBW Aviation...13
Hazardous Weather Outlook National Weather Service Louisville KY 319 PM EDT Wed Aug 18 2021 INZ076>079-083-084-089>092-KYZ023>043-045>049-053>057-061>067- 070>078-081-082-191930- Orange-Washington-Scott-Jefferson-Dubois-Crawford-Perry-Harrison- Floyd-Clark-Hancock-Breckinridge-Meade-Ohio-Grayson-Hardin-Bullitt- Oldham-Trimble-Henry-Shelby-Franklin-Spencer-Anderson-Woodford- Fayette-Bourbon-Nicholas-Nelson-Mercer-Jessamine-Larue-Marion-Boyle- Garrard-Madison-Butler-Edmonson-Hart-Green-Taylor-Casey-Lincoln- Logan-Warren-Simpson-Allen-Barren-Monroe-Metcalfe-Adair-Russell- Cumberland-Clinton- Including the cities of Paoli, Salem, Scottsburg, Madison, Jasper, English, Tell City, Corydon, New Albany, Jeffersonville, Lewisport, Hawesville, Hardinsburg, Brandenburg, Hartford, Leitchfield, Elizabethtown, Shepherdsville, Louisville, La Grange, Bedford, Milton, New Castle, Shelbyville, Frankfort, Georgetown, Cynthiana, Taylorsville, Lawrenceburg, Versailles, Lexington, Paris, Carlisle, Bardstown, Springfield, Harrodsburg, Nicholasville, Winchester, Hodgenville, Lebanon, Danville, Lancaster, Richmond, Morgantown, Brownsville, Horse Cave, Greensburg, Campbellsville, Liberty, Stanford, Russellville, Bowling Green, Franklin, Providence, Scottsville, Glasgow, Tompkinsville, Edmonton, Columbia, Jamestown, Burkesville, and Albany 319 PM EDT Wed Aug 18 2021 /219 PM CDT Wed Aug 18 2021/ This hazardous weather outlook is for portions of south central Indiana and Central Kentucky. .DAY ONE...Tonight. Scattered thunderstorms will continue this evening, especially across southern Kentucky. Some of these storms could be strong with gusty winds and torrential downpours. Overnight, showers and isolated storms are expected to develop across the region. Locally heavy rainfall will be possible. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Showers and isolated thunderstorms will be capable of locally torrential downpours Thursday morning. .SPOTTER INFORMATION STATEMENT... Spotters are invited to report heavy rainfall and instances of localized flooding tonight into Thursday. 13/EBW
The Nashville radar (KOHX), 55 km away, was scanning. The volume nearest the first event began at 21:35 UTC.
2 flash flood. Local standard time, as filed.
Dispatch reported water over Kentucky 100.
Highway 127 flooded between Goodyear and Bojangles.
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: 981060, 981061.