A cold front will pass through central Indiana Sunday evening. It will remain warm and humid before the front passes. There will also be a chance for a couple rounds of rain and thunderstorms.
Sunday morning will bring a chance for rain, with an embedded thunderstorm, to central Indiana. This round of rain looks to move in from the southwest starting as early as day break.
The morning round of rain will play a major impact on the chance for afternoon thunderstorms. If the rain arrives later in the morning, keeping the atmosphere a little cooler/stable, and holding clouds around the area, that will keep temperatures down for the afternoon and limit the threat for severe thunderstorms. However, I think we could see breaks in the clouds, allowing temperatures to climb to near 80°. Combine that with dew point temperatures in the low 60°s the atmosphere will begin to destabilize.
If you don't like strong/severe thunderstorms, root for clouds to stick around Sunday!
Computer models suggest a narrow corridor of instability will develop in the western/southern half of the state by mid-afternoon. This would allow thunderstorms to quickly strengthen once they develop.
The Storm Prediction Center has placed all of central Indiana in a "Slight Risk" for severe thunderstorms. I think the window for severe thunderstorms in the CBS4 viewing area is between 2:00 p.m. and 6:00 p.m. Sunday.
The main threat from thunderstorms will be strong winds. A secondary threat with a few thunderstorms will be damaging hail. As the storms move in to eastern Indiana, nearing the Indiana/Ohio state line, the tornado threat may begin to tick up as there is better support for tornado development in the upper-levels of the atmosphere (more divergence allowing air parcels to evacuate lower levels).
TROUBLE FOR THE TRACK
The threat of rain Sunday could make it difficult for the "Fast Nine" and the "Last Row Shootout" at the Indianapolis Motor Speedway.
While we are not expecting all day rain, rain in the morning could delay the start of qualifying the last row of the field of cars. The further qualifications get pushed back, the higher the chance for thunderstorms to impact the track during the afternoon.
I'm throwing a red flag for much of the day at IMS. That doesn't mean there couldn't be time to complete qualifications, but I think it will be difficult.
By mid-week an upper-level hot dome is projected to build in from the south, allowing temperatures to soar to the warmest levels of 2019. High temperatures are forecast to top out in the upper 80°s. I think there could be some locations reaching the low 90°s on Friday.
Along with the heat, the humidity will begin to increase. Dew point temperatures are projected to rise to the upper 60°s and lower 70°s. That means one thing. A return of the "mugglies". Right now the heat index is projected to climb in to the lower 90°s Thursday and Friday. If you plan to attend Carb Day Friday, do yourself a favor and start hydrating your body (with water) starting Wednesday.