The main weather impact on Friday will be winds, which will be sustained from the south at 15 to 25 mph, gusting between 30 and 35 mph at times. This could lead to some teams choosing to have limited running time on Friday, due to the tricky conditions the winds may cause.
The forecast for Saturday is looking better than it was the last few days, as the approach of a cold front has slowed down. This will put the best chance of rain on Saturday night. Still, there is a chance of some showers and thunderstorms during the day, mainly late in the afternoon. The models are not in very good agreement on timing, and some keep the daytime hours completely dry. Hopefully there will be enough time to get qualifying done before rain arrives.
Showers and thunderstorms are likely Saturday night, then the front will pass through early Sunday morning. Some scattered showers are possible Sunday morning, but I expect that they will be gone by the time the Top 12 practice session starts at 12:30 pm. Temperatures will be cooler on Sunday behind the front, which could help produce some pretty high speeds for qualifying.