A decaying Mesoscale Convective Vortex (MCV) pushed north into Indiana during the late afternoon hours of May 24th and interacted with a line of thunderstorms moving across Illinois. Initially these storms produced pockets of damaging winds with widespread sub-severe 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.
A decaying Mesoscale Convective Vortex (MCV) pushed north into Indiana during the late afternoon hours of May 24th and interacted with a line of thunderstorms moving across Illinois. Initially these storms produced pockets of damaging winds with widespread sub-severe winds. Later into the evening, outflow boundaries from these storms initiated one larger storm that produced isolated large hail across the southern Indianapolis metro.
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 May 24, 3:40 PM EST, 20 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Indianapolis IN 440 PM EDT Fri May 24 2024 .KEY MESSAGES... - Scattered to numerous thunderstorms through the early overnight, isolated severe threat - Thunderstorms, possibly severe on Sunday/Sunday Night/Monday - Shower chances and cooler temperatures Tuesday-Wednesday - Dry and Seasonable Thursday and Friday && .MESOSCALE UPDATE... Issued at 440 PM EDT Fri May 24 2024 Multiple lines of thunderstorms have developed across W and NW central Indiana this afternoon ahead of two separate lifting mechanisms. The first is a west to east moving outflow boundary from prior day convection over C IL. The second is a SW to NE moving pressure trough from a decaying MCV. Thermodynamically, sufficient amounts of CAPE still exist over western portion of central Indiana, with greatest values along the MCV pressure trough. This is likely the reasoning behind the higher storm tops and greater updraft strength with these cells. This instability drops off over east central Indiana. Wind shear will be the main mitigation factor, with effective shear values ranging from 25kts over western central Indiana to 15kts over eastern central Indiana. This will likely inhibit organization with most cells failing to sustain themselves. As these previously discussed lines merge, locally enhanced shear could allow for a quick uptick in storm tops and a briefly increase threat of damaging winds/large hail. This is primarily a concern over Vermillion, Fountain, and Montgomery counties, but could extend eastward if both lines are able to keep structural integrity. Outside of this, the main threat will be isolated severe downbursts within strongest cores over the next 3 to 4 hours. Given the lack of shear and weaker instability over eastern central Indiana, the threat should decrease as the convection moves over these areas. && .SHORT TERM (This evening through Saturday)... Issued at 227 PM EDT Fri May 24 2024 Rest of Today/Tonight. Storms have begun to initiate along the outflow boundary from the late overnight/early morning derecho that moved across Iowa as surface instability continues to increase. As of 2PM, Hi-Res models are showing upwards of 1500-2000 J/kg of surface based CAPE across central Illinois which is where the better axis of effective bulk shear. Across western Indiana values are generally less than 20kts with the weaker flow aloft. This will improve a bit closer to 00Z as the LLJ begins to ramp up but with a lack of shear the severe threat looks minimal without a more organized cold pool developing across Illinois which could push things eastward. The other potential concern for this evening/early overnight is a residual MCV from yesterday's convection across the Southern Plains as it pushes further into Arkansas and Tennessee and gets ingested into the LLJ and turns more northerly. So far the storms associated with this system have been brief and sub-severe with a lack of instability along and ahead of the MCV limiting the threat. Hi-Res models are picking up on the locally enhanced shear, but this seems rooted more in the 700-500mb layer which has generally been higher than the storms have been able to tap into so far. The tornado threat that often is enhanced by an MCV doesn't look to be the case this time around with observations not showing a stronger easterly wind component compared to what would normally be seen. Thoughts going into the evening hours are that the disorganized convection across Illinois will push in and gradually weaken after 3-4PM with additional pulse thunderstorms caused by forcing from the MCV across the southern half of the state through the early evening. It doesn't look likely that the southern storms will be able to root into the better shear aloft with a lack of instability and the lack of shear across the northwest will keep the severe threat minimal with lightning and a brief gust of wind from downburst as the primary threats. Isolated to scattered showers will continue through the rest of the night with dry weather by tomorrow morning. Saturday. A brief break in the more active weather is expected for Saturday as the parent upper level low from the Friday system pushes into Canada and the next low ejects from the Rockies. This low is expected to bring more widespread and intense strong to severe storms but that will be covered in the long term section below. For Saturday expect pleasant conditions as the skies clear through the morning and northwesterly surface flow keeps temperatures in the upper 70s to low 80s with dewpoints in the low to mid 50s for all but the southern third of the state which will be closer to 60. && .LONG TERM (Saturday night through Friday)... Issued at 227 PM EDT Fri May 24 2024 Saturday Night... Models shows moderate southwest flow in place aloft with little in the way of forcing dynamics present through the evening hours along with a dry forecast column. Surface high pressure will be set up over the southeastern states and low pressure is expected over Kansas. The low is expected to extend a warm frontal boundary across MO to Indiana. Dry weather will be expected in the evening, however overnight convection over middle Mississippi valley associated with an approaching wave aloft will push forcing dynamics toward Central Indiana overnight. Forecast soundings overnight are trending toward saturation late as the earlier convection advects east. Models are differing a bit on the timing, but for now at least chance pops during the overnight, especially across the west seem appropriate. With Central Indiana within the warm sector, lows will be in the middle and upper 60s. Sunday, Sunday Night and Monday... Confidence is high for a precipitation event on Sunday and Sunday Night. Confidence for precise timing of the showers/storms is much less so. Models suggest the moderate trough aloft pushing east into the middle Mississippi and Ohio Valleys. The trough looks to become slightly negatively tilted aloft as it pushes toward Indiana. Ample forcing dynamics appear present. After the possible morning convection, another round is suggested during the afternoon hours. Models suggest CAPE present ranging from 1500 to 3000 J/kg across the forecast area as a favorable atmosphere for convection will present. Thus with the warm frontal boundary in place to across Central Indiana and much of the forecast area within the forecast area. Thus we will include high pops through the course of the day on Sunday, although there still will be periods of dry weather. More precise timing will come into focus in the next 24-36 hours. On Sunday Night and into Monday, the upper low is expected to push northeast toward the Great Lakes and drag another trough axis across Indiana. Again this feature has ample forcing with plentiful CAPE available on Sunday night through early Monday. The associated surface low pressure system expected to push through the Great Lakes on Monday and will also drag a cold front across Central Indiana, exiting by late afternoon. Thus will need to keep some chance pops for the time period on Monday when our area resides within the warm sector ahead of the front. Tuesday and Wednesday... Strong ridging aloft is expected to build across the plains in the wake of the front. This will allow an area of cool, Canadian high pressure to settle across Indiana on Tuesday through Wednesday. Forecast soundings on these days show a dry column with little to no instability present. Thus will trend toward a dry forecast, partly cloudy days and mostly clear nights with seasonable temperatures. Thursday and Friday... Models suggest the strong ridging looks to remain over the mid section of the CONUS, but this will allow for the development of a weak Omega block, with the front end low setting up over the middle Atlantis States. This will bring cyclonic flow aloft over Indiana, influenced by the upper low to the east. Meanwhile at the surface, strong surface high pressure centered over the Great Lakes with cool easterly flow will be present across Central Indiana. The lower levels are not a favorable set-up for precipitation, but the cyclonic flow aloft cannot rule precipitation out. Thus it is likely that at least some small chance pops will be included at that time for now. && .AVIATION (18Z TAF Issuance)... Issued at 1256 PM EDT Fri May 24 2024 Impacts: -MVFR to IFR cigs 09Z to 14Z -MVFR to IFR vsbys during showers/storms -Best chance for TSRA from 22Z to 03Z Discussion: Convection is likely across much of central Indiana from the 22Z to 03Z timeframe with low confidence on the exact timing. MVFR to briefly IFR vsbys expected during periods of heavier rain but remaining VFR outside of those short periods. Cigs will gradually drop to MVFR during the late overnight hours with highest confidence from 09Z to 14Z. Winds will occasionally gust to 20kts this afternoon but otherwise will be light and variable at 4-8kts. && .IND WATCHES/WARNINGS/ADVISORIES... None. && MESOSCALE...Updike SHORT TERM...White LONG TERM...Puma AVIATION...White
Hazardous Weather Outlook National Weather Service Indianapolis IN 233 PM EDT Fri May 24 2024 INZ021-028>031-035>049-051>057-060>065-067>072-251845- 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- 233 PM EDT Fri May 24 2024 This Hazardous Weather Outlook is for Central Indiana. .DAY ONE...Through Tonight. Weather hazards expected... Elevated lightning risk. DISCUSSION... Scattered to numerous thunderstorms with isolated severe weather through the early overnight. The primary threat is damaging wind gusts. Locally heavy rainfall and hail are also hazards. Storm motion will generally be from the southwest at 20-30 mph .DAYS TWO THROUGH SEVEN...Saturday through Thursday. Thunderstorms are possible at times through Tuesday. Strong to severe thunderstorms are likely on Sunday. Damaging wind gusts and large hail are the primary threats, but tornadoes are also possible. Locally heavy rainfall may also be a threat. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report severe weather through the weekend. && This product in graphical format...along with other weather... hydrological and climate information...at: http://www.weather.gov/erh/ghwo?wfo=ind http://www.weather.gov/ind WFO IND
The Indianapolis radar (KIND), 56 km away, was scanning. The volume nearest the first event began at 20:58 UTC.
7 hail, 6 thunderstorm wind. Local standard time, as filed.
Several reports from dispatch of trees and powerlines downed by thunderstorm wind gusts across the eastern portion of the county.
Tree downed by thunderstorm wind gusts across US 231.
Several large tree limbs downed by thunderstorm wind gusts.
A hog barned was damaged by a locally stronger thunderstorm wind gust.
An 18 inch diameter and 40 foot fall healthy tree was snapped by thunderstorm wind gusts. Several other reports of damage across the county.
Tree downed by thunderstorm wind gusts onto a house. Other trees in the yard snapped.
Large volume of hail.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Indiana in 2024Every state in 2024This day in weather historyWarnings in Indiana, May 2024
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: 1168972, 1168971, 1168973, 1168976, 1168974, 1168994, 1168975, 1168978, 1168979, 1168980, 1168981, 1168983, 1168984.