For Friday and Saturday, the forecast hasn't changed much. Friday will start off mostly sunny, but clouds will be increasing through the day. There will probably be more sun than clouds from Friday afternoon through Saturday due to an easterly wind off the ocean. This moisture will be shallow enough that I don't think there will be any rain, at least not until Saturday night. I can't rule out a few sprinkles on Saturday night, but it expect that it would not have an impact on the race.
With Tuesday's update, I showed how two models were showing very different rainfall amounts between 10 am and 4 pm. Here are the same two models, from today's morning run, with their prediction for rainfall in the same period of time:
Here's an animation of another model, the NAM, and its depiction of rainfall between 7 am and 7 pm (each time step is three hours apart - 7 am, 10 am, 1 pm, 4 pm, and 7 pm):
So here's what I'm thinking today about what to expect on Sunday - there may be a few sprinkles early in the morning, but not enough to have any significant impact. Light rain showers (more than just sprinkles) are likely to arrive at the track in the mid to late morning, starting between 9 am and noon. Light on/off showers will continue from noon until the end of the race, with the rain getting heavier after the race ends, probably between 3 pm and 6 pm. The amount of rain from the time it starts to the end of the race will likely be between 0.05 and 0.15 inches. If that happens as expected, then the rain tires should be able to handle it, and I don't foresee the race having to be stopped.
There is still 72 hours and several more model runs before we get to Sunday afternoon, so this could change completely before then. But that's what I'm thinking right now. I'll have another update on Saturday at the latest.