The graphic above gives a general idea of what conditions you can expect through the race. It will start off partly cloudy, but the clouds will be increasing through the afternoon. By sunset (which is around 4:40 PM), clouds should be covering the sky and temperatures will fall into the 40s. The main weather feature that is bringing rain is a disturbance in the mid and upper levels of the atmosphere. Rain with the system is expected to start between 2 AM and 5 AM, and I'm confident that it will be raining before sunrise (which is around 7:20 AM). The period of heaviest rainfall is expected to be between 5 AM and 9 AM.
Rain should start to decrease late Sunday morning, but there will likely still be some showers around the track through the end of the race, which is at noon. The total amount of rain expected during the race is between a tenth and a quarter inch.
I'll do my best to have live weather updates through the race on my Twitter account (@Race4caster). You can always check the radar using the link at the top of the website.