By Lynne Huntting
The Thursday morning weather started out beautiful at Indianapolis Motor Speedway where the MotoGP teams were settling in for this weekend's inaugural Red Bull Indianapolis GP.
There were blue skies, warm weather and a nice breeze. Happy fans were streaming through the huge circuit, which is looking forward to celebrating its Centennial.
However, the weather started clouding over and by afternoon's end the skies were completely grey and the forecast was looking grim, literally and figuratively.
A drizzle hit and ran, freshening up the air. Two hours later it bucketed.
Friday's forecast calls for 90 percent chance of rain - Thunderstorms. The temperatures will be mild, ranging from 67F/19C to 77F/25C with southwest winds 5 mph/8 kph.
Weather is always crucial at Indy because among other things, it is so changeable.
Another interesting variable to look out for is the track surface, which changes from corner to corner and even within some corners.