Southern IL Forecast


HRRR precipitation depiction showing heavy rains moving in overnight tonight along the stalled boundary along I-70.

I have received just under an inch so far today here in Alton but we still have plenty of rain on the way. In fact, we have a chance to see rain every day for the remainder of the week. 

Focusing on today/tonight, southwest flow should continue to usher in moisture from the Gulf of Mexico ahead of a surface low tracking in from the Plains. The boundary will sink south and stall out near/along I-70 this evening. With the low-level jet ramping up overnight tonight and precipitable water values around 1.5″, our convection will be very efficient rain-makers. Not expecting anything severe out of this, but flash flooding/flooding is certainly possible and the NWS has Flood Watches in support of that notion. Widespread 2-3″ rainfall totals should exist through Tuesday night with isolated pockets of higher amounts. Carbondale to Evansville and points south will likely see 1-2″ of rain through Tuesday night with locally higher amounts. 

The wet pattern will continue as we will have multiple waves of energy move through the forecast area. After this current system moves out, a lobe of southern stream energy will propagate through our area late Wednesday into Thursday ushering in another round of showers and Thunderstorms along the front and the work week will end with the northern stream sending an impulse down the pipeline. 

It’s a little early to provide an estimate on rainfall estimates looking ahead to Wednesday night-Saturday morning since we still have some strength/placement/timing issues to iron out so expect those details in future outlooks.

Southern Stream lobe of energy that will bring precipitation chances Wednesday night into Thursday.
Northern Stream lobe of energy that will bring precipitation chances Friday.