High pressure will dominate the weather for Friday and Saturday, and with that happening, you will notice a rise to those afternoon highs. We'll have mostly clear skies on both days with Friday's high topping out around 80 degrees, and Saturday's high in the upper 80s. An approaching low will cause a tightening in the pressure gradient on Saturday, so winds will be a little breezy out of the southwest averaging 10-15 MPH.
That approaching low over the Dakotas may allow for a few isolated showers to form nearby during the late afternoon and into the early evening hours, and one may pass over the track before the end of the race day on Saturday, but the chances of that occurring will be around 20%.
Sunday will be another very warm day with breezy winds as that low pressure center weakens and moves across the southern parts of Minnesota. This will continue to be the catalyst for a few isolated showers to develop during the afternoon hours. Rain chances at this point are still very small, around 20%. Afternoon highs will be back up into the mid-80s with winds out of the southwest at 10-15 MPH.