By Doug Schneider
The forecast for the 100th Indianapolis 500 was a mixed bag of hits and misses. The general pattern throughout the events was a southerly flow of warm, moist air that provided weak instability and hit-or-miss showers each day. There wasn't a well-defined low pressure system or front that moved across the area to provide organized showers and thunderstorms, which is part of what made the precipitation forecast difficult. I knew there would be some showers around each day, but the question was whether they would hit the Speedway. Given the weather pattern, fans at the Speedway were very fortunate to dodge most of the showers through the event.
Showers and thunderstorms rolled through Speedway in the early afternoon on Thursday, producing around a quarter inch of rain. The early arrival of the rain kept temperatures in the 70s all day, a little cooler than forecast. Friday turned out to be a dry day, and my 50% rain chance was definitely too high. The abundant sunshine on Friday raised temperatures into the mid 80s, a bit above my initial forecasts. There were some showers around central Indiana on Saturday, but they managed to just avoid the Speedway. A trace of rain was recorded at the airport on Saturday. In retrospect, a 50-60% rain chance in the forecast was probably on the high side, but at least there was some rain in the area.
The Indy 500 on Sunday was SO close to being interrupted by thunderstorms. Around 2 pm, a thunderstorm passed just a few miles north of the Speedway. While there was an extended caution flag period for light sprinkles, the weather didn't cause any problems or significant delays, as I had been expecting. But it was very, very close. I was sweating it out there for a while, keeping one eye on radar and one on the race.
For the month of June, Scott will be busy preparing the forecasts at all the Road America events as part of our partnership with them. I'll be forecasting for the rest of the events on our schedule, including Le Mans.