Here's a timeline for you:
At 9:27 PM EDT on May 30, NWS issued a Tornado Warning for NORTHERN HENDRICKS, SOUTHEASTERN MONTGOMERY, NORTHEASTERN PUTNAM COUNTY. (Sorry for the all caps...I'm cutting and pasting from NWS text products.)
At 10:11 PM EDT, NWS issued a Severe Thunderstorm Warning for SOUTHERN BOONE, SOUTHERN HAMILTON, HENDRICKS, MARION COUNTY.
From The Indianapolis Star:
The National Weather Service said the twister touched down at 10:27 p.m. at 42nd Street and Post Road, and traveled 2.5 miles to East 38th Street and Black Locust Drive just east of German Church Road in the next three minutes.
At 10:32 PM EDT, NWS issued a Severe Thunderstorm Warning for SOUTHEASTERN HAMILTON, HANCOCK, SOUTHERN MADISON COUNTY.
At 10:34 PM EDT, NWS issued a Tornado Warning for NORTHWESTERN HANCOCK COUNTY.
At 10:47 PM EDT, NWS issued a Tornado Warning for NORTHEASTERN HANCOCK, SOUTHEASTERN MADISON, WESTERN HENRY COUNTY.
The tornado that touched down at 42 and Post was apparently not spotted by anybody before it hit. There was a funnel cloud spotted near North Salem, Indiana, in northwestern Hendricks County about an hour before the tornado touched down in northeastern Marion County. One of our spotters in north central Hendricks County thought he was seeing a lowering of the cloud base which might have been a tornado. This was reported to NWS. As you scan through the storm reports on the NWS web site, you see lots of heavy rain and high wind reports from northern Hendricks and northern Marion Counties, but no wall clouds, funnel clouds, or tornados.
We have been spoiled by all of the tornado videos we are seeing on television these days. Most of those are shot in Kansas, Oklahoma, and Texas where the tornados are very easy to spot because the supercells that are generating the tornados don't produce a lot of rain. In this part of the country, we get a lot of high precipitation supercells. It's very easy for a tornado to be "rain wrapped" making it nearly impossible to see, especially at night.