Slow Moving Storm Brings Steady Rain & Flooding Concerns to the Stateline

I wouldn't put the rain gear away just yet. The same storm system that brought scattered thunderstorms to the Stateline on Tuesday, will be behind shower chances we see today.

To get into "the why", we'll have to take a gander higher up in the atmosphere, roughly 16,000 to 18,000 feet up. A slow moving mid-level low is pivoting across the Midwest, while the surface low is currently parked on top of northern Illinois. The mid-level low is going to become what we call "closed off" from flow in the mid-levels by the time it reaches the Great Lakes region. In meteorological terms, a closed off low typically means that there it is incapable of being steered by the mid-level flow. With this low then sitting just to our east, and nothing to steer it away, this is going to place the Stateline in a prime spot for rain chances.

As an abundance of moisture pivots around the surface low, that has already lead to scattered showers and an isolated thunderstorm or two for areas east and northeast of Rockford. Showers are going to become more widespread by late morning, turning into a more steadier rain by this afternoon and evening, with pockets of moderate to heavy rain also possible. This will lead to 1-2" of rainfall in some locations, with totals up to 3" in a few localized areas. And since the region is going to be so close to the surface low, today also features very windy conditions. Winds will pick up our of the north-northwest as we close in on the afternoon hours, and gusts could top off near 30 to 35 MPH. This could lead to loose objects being blown around, and even a few weakly snapped tree branches. As far as when we will see a break from the rain, a few spotty showers may linger into Thursday. But the rainy start will give way to drier conditions by late tomorrow afternoon and evening, but breezy weather is going to persist.

Now, there is a concern for flooding with the rain that we will see over the next 24 hours. For that, the National Weather Service has issued an areal flood watch until midnight Thursday morning. This is for the eastern portions of the viewing area, including Boone, DeKalb, and McHenry Counties in northern Illinois, and Walworth County up in southern Wisconsin.

In these locations, as much as 2" of rain has already fallen. Another 1" to 2" of rain could fall between early Wednesday and Thursday. Once we see this showery stretch come to an end come to an end, rises in rivers and streams are likely, with flooding being a possibility in poorly drained areas.