Another round of heavy rain is not exactly what the Stateline needs, but it's possible this evening.
Southerly winds continue to draw up a warmer and more humid air mass through Wednesday afternoon. PWAT (or precipitable water/available moisture) values will be again rather high today. Numbers go up to about 2" which means it's possible for 1.50" to 2" of rain to fall across the area. In general, it will be more probable for about 0.50"-1.00" of rain, with locally higher amounts in the stronger storms.
The axis of heaviest rain though has shifted to the south, around the Quad Cities, south to Peoria, and near Des Moines.
This is where the National Weather Service has issued a Flash Flood Watch, which includes Whiteside county in the Stateline. In this area its possible for up to 2.5" to 3.0" inches.
An isolated storm or two is possible in the mid to late afternoon, around 3/4pm, but the higher chance for strong storms with heavy rain will arrive closer to 6/7pm from the west and will continue through midnight. A few lingering storms will continue through Thursday morning, but the severe threat will be low. An isolated shower will be possible in the afternoon, as there will be a bit of instability present with cooler air arriving.