Friday appears to have the best chance of rain, but there are big differences in the models about where the rain will fall due to their different tracks of the low pressure system. The wettest model (ECMWF) takes the low across the southern Great Lakes, and produces a lot of rain at the track on Friday - over one inch. The GFS model has a weaker low that tracks much farther south, along the Ohio River. It keeps the bulk of rain well to the south of Mid-Ohio, with only some light rain at the track, if any at all. Another model (Canadian) is somewhere in between. So with this uncertainty, I will go with a 50/50 chance of rain at the track on Friday. It's too early to forecast rainfall amounts at this time due to the wide spread in the models. Temperatures will depend on how much rain and cloud cover there might be, but lower 80s appear to be the most likely scenario.
My low confidence continues into Saturday, but it generally looks like it will have a lower chance of rain than Friday. Even though the surface low pressure system will be east of Ohio by Saturday, there will still be an upper level trough that will track across the region, as well as a lingering boundary at the surface. This may bring some showers at the track, but at this time, I expect that they will be few and far between. The majority of the day will likely be dry, with high temperatures in the lower 80s.
There is some model agreement that Sunday will be dry, and although I'm not 100% confident that it will be, I think that a dry day is the most likely scenario. The upper level trough should be east of Ohio by this time, with drier air aloft and surface high pressure building in from the west. With fewer clouds and more sunshine likely, temperatures should be a little warmer, with highs in the mid 80s.
Stay tuned for updates through the week, as this forecast is likely to be adjusted in the next few days.