A cold front is still on track to cross the area on Saturday, which will bring a better chance of rain. The best chance of rain appears be mainly in the late afternoon and evening hours, although I can't completely rule out a shower at any time. The amount of rain still does not look especially heavy, and will most likely be in the range of a tenth ot a quarter inch. Still, there is some potential for up to a half inch through the afternoon and evening if multiple heavy showers pass over the raceway. I think this is unlikely though, and the race should be able to continue through any rain showers.