Numerous early afternoon convective cells over north-central central Indiana quickly transformed into a strong squall line over northeastern central Indiana, which produced damaging winds.
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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 IND wrote it up.
Numerous early afternoon convective cells over north-central central Indiana quickly transformed into a strong squall line over northeastern central Indiana, which produced damaging winds.
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 Indianapolis, IN wrote its last area forecast discussion before the first event at Aug 11, 1:04 PM EST, 51 minutes earlier.
Area Forecast Discussion National Weather Service Indianapolis IN 204 PM EDT Wed Aug 11 2021 ...Updated Aviation Discussion... .Forecast Update... Issued at 1006 AM EDT Wed Aug 11 2021 Forecast is currently on track to be a hot day with the potential for storms. At the moment radar shows thunderstorm complexes to the NW in Illinois and to the NE in Ohio, but the radar over central Indiana is clear for now. Uncertainty remains as to whether storms will be able to get going today given the lack of large scale forcing, but if some do, the amount of potential instability is enough that they could produce severe weather. Temperature trends are on track to reach the low 90s by this afternoon and with the influx of southerly moisture, heat indices into the 100s will likely come to fruition this afternoon. && .Short Term...(Today through Thursday) Issued at 300 AM EDT Wed Aug 11 2021 ...HOT AND HUMID WITH CONTINUED CHANCES FOR STRONG TO SEVERE STORMS... Today Early this morning, an upper trough will moving through Lower Michigan, creating showers and thunderstorms that stretch down to the northern border of the forecast area. An outflow boundary from these storms was across the far northern forecast area. Additional showers were across southern Illinois. VAD 850mb winds show speeds of 35kt. With the 850mb winds remaining up and an outflow boundary in the area, wouldn't be surprised to see scattered convection continue to pop up at times in the pre-12Z time frame. In addition, thunderstorms will be developing in northern Illinois thanks to the 850mb flow. Some of these may get into the northern forecast area late in the pre-first period or early in the Today period. Will go with chance PoPs north and slight chance PoPs south, some continuing into the early Today period. During the remainder of the day today, there isn't much forcing around with the near zonal flow aloft and no large scale surface features. However, smaller scale features such as the leftover outflow boundaries will remain. Warm temperatures will remain in the mid-levels, with temperatures of 10-12C, adding some capping. Thus, feel any convection that gets going today will be from mesoscale features or small impulses in the upper flow that are hard to diagnose. Given the lower coverage of rain on Tuesday with the warm mid levels, will just go with some slight chance PoPs this afternoon. Strong instability will lead to a threat of severe storms if anything can get going. The other issue will be heat. The current mid level clouds should mix out this morning, and cirrus from convection should thin out as well. The sunshine plus dewpoints in the mid to upper 70s will lead to heat indices up to around 105 again today. Will continue Heat Advisory and expand it to the remainder of the forecast area. Tonight Some upper energy will move through the lower Great Lakes tonight, likely sparking thunderstorms there. The question is will any of these survive into central Indiana. While there will be instability, the mid levels will remain warm. The source of forcing will remain well to the north as well. Pretty much all CAMs weaken or even dissipate the line before it impacts central Indiana. Thus have low confidence in convection. If the storms do survive, they will still have a threat for severe, especially in the evening with the high instability. Thursday Thursday should be similar to today, with no significant sources of forcing but strong instability around. Storms could fire on remnant outflows or even if there are any MCVs from previous convection. Mid levels remain warm. Given these, will just go with some chance PoPs once again, with the highest PoPs in the north nearest the most likely locations of remnant outflows or MCVs. With little change in airmass and sunshine, another hot and humid day is expected. Depending on what happens tonight with the storms, may have to extend the Heat Advisory into Thursday in later issuances. && .Long Term...(Thursday night through Tuesday) Issued at 300 AM EDT Wed Aug 11 2021 The pattern will finally begin to shift at the start of the long term period as this continued pattern of daily storm chances and 90 degree temperatures will come to an end after a seasonably strong frontal system moves through. During the overnight hours Thursday night, a strong closed low pressure system will be moving through the Hudson Bay area with a strong jet stream across the Northern United States. A surface cold front associated with this system is expected to pass through the area during the daytime hours on Friday bringing additional thunderstorm chances and a relief from the heat. The severe weather threat with this system is going to be dependent on the exact timing, but current indications are that the front should pass through during peak heating which would suggest that at least a few strong to severe storms are possible. The best shear and instability though look out of phase with the best shear across the post-frontal areas while the best instability looks to be out ahead of the front. Will continue to monitor the threat going forward, but do think that scattered thunderstorms are likely with lower confidence on the severe threat. Dry and cooler weather is then expected for the weekend with strong subsidence at the surface along with a 1026mb surface high across the area through Sunday night. Small chances for precipitation returns Monday and Tuesday as the surface high breaks down and the remnants of the frontal system from the previous week begin to slowly meander back to the north. Earlier model guidance also suggested there may be some moisture from the incoming tropical cyclone, but latest runs have backed off on the moisture getting caught up in the westerlies and rather keeping the moisture across the south well into next week. && .Aviation...(18Z TAF Issuance) Issued at 203 PM EDT Wed Aug 11 2021 IMPACTS: - Mainly isolated convection possible through the period. - Wind gusts over 20kt possible this afternoon, otherwise speeds generally 10-15kt from 200-230 degrees. - Low level wind shear threat overnight and possibly into tomorrow morning DISCUSSION: VFR conditions are expected outside of any convection. Odds of organized convection and coverage of other convection are too low to mention TSRA in most TAFs, although it will be more likely at LAF overnight. MVFR or worse conditions are possible in any storm. Gusty winds are possible this afternoon with gusts diminishing in the evening. There will be a threat of low level wind shear overnight and into tomorrow morning. && .IND WATCHES/WARNINGS/ADVISORIES... Heat Advisory until 8 PM EDT this evening for INZ021-028>031- 035>049-051>057-060>065-067>072. && Update...KH Short Term...50 Long Term...White Aviation...KH
Hazardous Weather Outlook National Weather Service Indianapolis IN 349 AM EDT Wed Aug 11 2021 INZ021-028>031-035>049-051>057-060>065-067>072-120800- Carroll-Warren-Tippecanoe-Clinton-Howard-Fountain-Montgomery-Boone- Tipton-Hamilton-Madison-Delaware-Randolph-Vermillion-Parke-Putnam- Hendricks-Marion-Hancock-Henry-Vigo-Clay-Owen-Morgan-Johnson-Shelby- Rush-Sullivan-Greene-Monroe-Brown-Bartholomew-Decatur-Knox-Daviess- Martin-Lawrence-Jackson-Jennings- Including the cities of Delphi, Flora, Williamsport, West Lebanon, Lafayette, West Lafayette, Frankfort, Kokomo, Attica, Covington, Veedersburg, Crawfordsville, Lebanon, Zionsville, Tipton, Fishers, Carmel, Noblesville, Anderson, Muncie, Winchester, Clinton, Newport, Rockville, Greencastle, Plainfield, Brownsburg, Danville, Indianapolis, Greenfield, New Castle, Terre Haute, Brazil, Clay City, Spencer, Martinsville, Mooresville, Greenwood, Franklin, Shelbyville, Rushville, Sullivan, Linton, Bloomfield, Bloomington, Nashville, Columbus, Greensburg, Vincennes, Washington, Loogootee, Shoals, Bedford, Mitchell, Seymour, Brownstown, and North Vernon 349 AM EDT Wed Aug 11 2021 This hazardous weather outlook is for central Indiana. .DAY ONE...Today and Tonight. Thunderstorms are possible through tonight across much of central Indiana. Isolated severe storms are possible, mainly this afternoon and tonight across areas along and north of Interstate 70. The primary severe threats will be damaging winds and large hail. Lightning, gusty winds, and heavy rainfall are possible with any storm. Storm motion will be generally from the west or southwest at around 30 mph. Heat indices will reach up to around 105 degrees this afternoon. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Thunderstorms are possible over all or parts of the area Thursday and Friday. A few of the storms on could become strong to severe, with damaging winds and large hail the primary severe threats. Locally heavy rain is possible with any storm. Peak heat indices will remain in the upper 90s to around 105 degrees for most locations through Thursday. .SPOTTER INFORMATION STATEMENT... Spotter activation is possible at times today into Friday. && More information, along with other weather, hydrological and climate information can be found at http://weather.gov/ind
The Indianapolis radar (KIND), 90 km away, was scanning. The volume nearest the first event began at 18:52 UTC.
1 thunderstorm wind. Local standard time, as filed.
Report of partial collapse of an unoccupied metal warehouse structure.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Indiana in 2021Every state in 2021This day in weather historyWarnings in Indiana, 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: 971333.