Looking into Saturday morning temperatures are expected to bottom out near 30 F and be on the rise throughout the day, due to warm air advection by the high pressure system skirting by to the south of Indiana as seen in Figure 1, peaking in the mid to upper 40s. Due to some remaining moisture from the previous day or two in the atmosphere as well as some positive pressure advection, leading to rising motion, partly sunny skies will dominate much of Saturday and begin to clear out come Saturday night. (Pressure advection can be seen in Figure 2).
Moving into Sunday morning a low pressure system is expected to form off to the west over the Montana/Canadian border, inducing a ridge pattern over Indiana, as seen in Figure 3. This ridge pattern will lead to some strong warm air advection pushing temps into the lower 50s on Sunday and temporarily lowering the moisture levels in the upper atmosphere to allow for sunny skies.
Figure 1: Modeled 2 meter temperatures at 18z Saturday from the NAM. 10 meter wind barbs have been overlaid as well as MSLP contours.
Figure 2: 300K Isentropic Pressure Advection map derived from GFS and sourced from http://www.atmos.albany.edu/student/tburg/analysis/loop.html
Figure 3: 850mb Dewpoint Temperatures overlaid with isobars and wind vectors.