Latest from the website:
"Friday, April 22 update (4:30pm):
Wow, it quit raining. It's a Good Friday miracle! The radar looks clear now; there's still a chance of some rain overnight but it seems to be decreasing. Tim says if we don't get a bunch of rain overnight, and it's clear in the morning, he can fix the track. Perfect track? Nope, not tomorrow. But it'll be pretty good for Michigan in the springtime. The pits will be worse than the track, so try to bring smaller rigs (if the gas prices haven't already convinved you).
Check back in the morning just in case we get soaked overnight. "