An upper level trough will be exiting the region today. The clouds from this trough will gradually be decreasing through the day, with some sun peeking through by the late afternoon. High pressure from the surface through the midlevels of the atmosphere will be building over central Indiana tonight and Friday. Weather for Carb Day and Legends Day continue to look absolutely perfect, with plenty of sunshine and highs in the lower to mid 70s. Clouds may be be increasing Saturday afternoon as a low pressure system develops over the Plains.
The models are trending slower with the development of the low pressure system over the Plains, and are keeping the high pressure ridge over Indiana a little longer than previous models runs. The chance of rain on Sunday appears to hold off until the afternoon, and the majority of that rain chance will probably be late in the afternoon after the end of the race. Although I have a 40% chance of rain on Sunday (covering 8 am to 8 pm), I would put the chance of rain during the race at only 20%. A mix of clouds and sun is expected to start the day, with clouds becoming predominant by the afternoon. This should keep high temperatures in the 70s.
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