Scattered thunderstorms developed over west central and north central Indiana Saturday evening along a northward-moving warm front. A couple of the storms became severe with numerous wall clouds and funnel clouds.
Every event with a place to put it. Tap one for its entry below.
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.
Scattered thunderstorms developed over west central and north central Indiana Saturday evening along a northward-moving warm front. A couple of the storms became severe with numerous wall clouds and funnel clouds. One storm produced a brief tornado in the town of Forest in northeast Clinton County, causing significant damage to a fire station and a pole barn. Another storm produced a brief tornado in Boone County. The tornadic threat transitioned to a heavy rain and flash flooding threat in the Howard County area. Widespread flash flooding was reported in the Kokomo area with many roads impassible and some water rescues.
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 20, 5:37 PM EST, 1 hour 3 minutes earlier.
Area Forecast Discussion National Weather Service Indianapolis IN 637 PM EDT Sat May 20 2017 .UPDATE... The AVIATION Section has been updated below. && .SYNOPSIS... Issued at 302 PM EDT Sat May 20 2017 A cold front will slide east across central Indiana overnight and Sunday. The front will interact with a warm, moist and unstable airmass and result in widespread thunderstorms. The storms will be ending from west to east overnight and Sunday morning. High pressure will usher in seasonably dry weather through Monday. Then, an upper low pressure area will bring more showers and thunderstorms and cool temperatures to the area through the middle of next week. Warmer temperatures and more showers are possible next weekend as another frontal approaches from the west. && .NEAR TERM /Tonight/... Issued at 302 PM EDT Sat May 20 2017 Main focus tonight will be on timing and coverage of thunderstorms. Models in good agreement that an upper low will lift from Nebraska to the northern Plains by 12z Sunday. In response, a surface low will lift from southwestern Iowa northwestern Wisconsin. The thunderstorm complex, that went through central Indiana earlier, has now moved into northern Indiana. Satellite was showing breaks in the cloud cover which should allow the southern Indiana front to move northward and the atmosphere to de-stabilize once again ahead of a cold front, that was sagging south from the surface low, across western Missouri and the southern Plains. The front should be just to the west of a Kokomo to Indianapolis to Bedford line by daybreak. The front will interact with the very moist and unstable atmosphere and should result in numerous thunderstorms. The thunderstorms will be ending overnight west of the front and continue east of the front. Pre-frontal precipitable water values will be near-record around 1.70 inches at ILX and ILN. In addition, central Indiana will be within the right rear entrance of a 105 plus knot jet streak over western Wisconsin. All this suggests heavy rain is possible. In addition, 30-40 knot 1000-500 bulk shear suggests a few strong or severe storms are possible, mainly during the late afternoon and early evening, when surface base CAPES should exceed 1000 j/kg. Blend lows in the lower and mid 60s look good tonight with the cooler temperatures in the wake of the cold front. && .SHORT TERM /Sunday through Tuesday/... Issued at 302 PM EDT Sat May 20 2017 Main challenge for the short term will be timing the showers and thunderstorms out of the area in the wake of the cold front and also will be on timing and coverage of the return of unsettled weather associated with an approaching upper low. Models are in good agreement that the showers will be ending near and west of a Kokomo to Indianapolis to Bedford line by 12z Sunday and over with across all of central Indiana by 18z, as the front moves into Ohio. Skies will be decreasing Sunday afternoon with seasonable blended highs in the lower and mid 70s looking reasonable. It will be cool Sunday night under high pressure. Some areas may dip to the 40s. Look for slightly below normal temperatures Monday despite a good deal of sunshine expected. Models then in good agreement that an upper low will rotate southeast across the western Great Lakes by late Tuesday. This will promote more showers by Tuesday. Although areas near and west of Tipton and Terre haute could see an overnight storm Monday night. For now chance pops look good for most of the forecast area, but chances look a little better northwest. With extensive cloud cover, below normal temperatures are a good bet. && .LONG TERM (Tuesday night through Saturday)... Issued at 150 PM EDT Sat May 20 2017 There is good confidence it will rain either Tuesday night or Wednesday, and that Friday should be dry. Otherwise there is much forecast uncertainty. The American and European models disagree on the timing of systems that would cause precipitation. The exception is they both have Indiana covered by dry high pressure Friday. Depending on which model ends up best, POP errors may be as high as 20 percent. The American and European models also disagree about cool Canadian air arriving in the Hoosier state. This makes temperature forecasts progressively more uncertain. Errors through Wednesday night should be 2 degrees or less. Errors late in the period could be 5 degrees. && .AVIATION /Discussion for the 210000Z TAFS/... Issued at 636 PM EDT Sat May 20 2017 Convection is starting to develop over eastern Illinois and western Indiana in advance of an upper level vorticity lobe pushing east across Illinois. Convective threat at the terminals looks be rather high throughout the evening and into the late night hours as this feature interacts with an unstable air mass locally and a diffuse frontal zone. Brief IFR visibility restrictions and gusty shifting winds in and near heavier cells. Short term model guidance suggests this feature will pass off to the east of the terminals around 210900Z, so should see convective threat diminish by that time. Otherwise, expecting lower ceilings 010-015 to develop towards sunrise Sunday in the wake of upper level feature. Surface winds 150-180 degrees at 8-11 kts this evening will gradually veer around to 200-230 degrees by sunrise Sunday. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && SYNOPSIS...MK NEAR TERM...MK SHORT TERM...MK LONG TERM....JK AVIATION...JAS
Hazardous Weather Outlook National Weather Service Indianapolis IN 419 PM EDT Sat May 20 2017 INZ021-028>031-035>049-051>057-060>065-067>072-212030- 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 Lafayette, Frankfort, Kokomo, Crawfordsville, Anderson, Muncie, Indianapolis, Terre Haute, Shelbyville, Bloomington, Columbus, Vincennes, Bedford, and Seymour 419 PM EDT Sat May 20 2017 This hazardous weather outlook is for central Indiana. .DAY ONE...Tonight. Outlook: Scattered thunderstorms will occur tonight. There is a slight risk of severe thunderstorms with damaging winds...large hail...lightning and heavy rainfall being the main threat. An isolated tornado is also possible. Hazards: Damaging winds...Large Hail...Heavy Rainfall...Lightning and an isolated tornado. Timing: After 500 pm for thunderstorms and associated impacts Discussion: Low pressure will track across the upper midwest towards the western great lakes tonight sweeping a cold front across Indiana. This will generate showers and thunderstorms across the area. .DAYS TWO THROUGH SEVEN...Sunday through Friday. Outlook: A few thunderstorms are possible over eastern sections early Sunday morning...all areas Tuesday and over southern sections Wednesday afternoon. None of these are expected to be severe at this time. Discussion: A cold front will move east into Ohio Sunday. Another cold front will move our way Tuesday and a closed upper low will move our way around the middle of next week. This will be followed by an area of high pressure which will move our way late Thursday and Friday. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed later today. && More information, along with other weather, hydrological and climate information can be found at http://weather.gov/ind PUMA
The Indianapolis radar (KIND), 59 km away, was scanning. The volume nearest the first event began at 23:41 UTC.
2 tornado, 1 flash flood. Local standard time, as filed.
A brief EF-1 tornado touched down west of Thorntown in Boone County. Winds estimated at 90 mph damaged a barn by removing a large section of roof and tossing it several hundred yards into a field. One of the barn's walls collapsed.
An EF-1 tornado briefly touched down in Forest, Indiana. The approximate 95 mph tornado winds caused significant damage to a fire station and a nearby pole barn. Some roof damage also occurred to a home.
Due to thunderstorm heavy rainfall, a report of multiple accidents and cars stuck in flood waters came in via Kokomo 911 scanner. Multiple road were deemed impassible.
Indiana Heights in Southern Kokomo was reportedly completely flooded in some areas, especially in the area between Chippewa Lane and Tomahawk Boulevard. The flooding was reported to be to the point that it was over the sidewalks, into some of the yards water was just below the mailboxes at a lot of places.
Indiana 26 was closed down for about two hours between Park Road and Indiana 931 because of flooding.
Tow trucks were sent to an area on East Boulevard Street and the plaza near the Indiana 931 and Boulevard Street intersection, where cars needed to be pulled from high waters. There was also standing water in the Chrysler parking lot.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Indiana in 2017Every state in 2017This day in weather historyThe tornado archive for Indiana, 2017Warnings in Indiana, May 2017
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: 703193, 703268, 704448.