The low pressure center will track east across central Florida on Thursday, followed by a cold front. This will keep rain showers and possibly a few thunderstorms going through the day, although the rain amounts on Thursday will likely be less than Wednesday, probably around a quarter inch or so. But the question remains, when will the rain end? The majority of the models show a cold front moving through the Daytona area in the afternoon, and dry air builds in shortly after, ending any chance of rain in the evening. There is one model (the NAM) that is much slower with the cold front and drier air, keeping rain over Daytona until early Friday morning. I favor the faster model consensus, and I think the majority of the rain on Thursday will come in the morning, with decreasing rain chances through the afternoon, and any rain chance ending before midnight. This is what I've been forecasting since Sunday, and I'm going to stick with it. While there will be a chance of rain all day on Thursday, the afternoon qualifying sessions are more likely to take place than the morning practice sessions.
Here is the forecast rainfall amount map from the National Weather Service for Wednesday through Thursday night (again, the majority of this rain will fall on Wednesday). That's about 2 inches at Daytona (the white dot).
The forecast graphic in Celsius: