PEORIA, IL — A lot of rain is on the way for Illinois over the coming days as a moisture surge from Hurricane Polo moves into the Midwest. Wednesday will be soggy for areas north of Springfield. Another wave hits the northern half of the state on Thursday, and rain spreads into the southern half on Friday. The heaviest rain is expected across the northern third of Illinois, where 2 to 4 inches are likely and pockets of 5 inches are possible. No severe weather is expected with this system.
Northern Illinois Takes the Brunt of the Rain
The five-day rainfall forecast, covering September 29 through October 4, puts the heaviest totals over northwest and north-central Illinois. Sterling and the Quad Cities are each forecast near 3.6 inches, and Rockford is close to 3.4 inches. DeKalb is projected near 3.2 inches, Princeton about 3.1 inches, and Galena around 2.8 inches.
A pocket of the 4 to 6 inch range shows up on the forecast map just south of Rockford and near Sterling, and it extends west across the Mississippi River into eastern Iowa. These are the areas most likely to see 5-inch totals if heavier bands keep hitting the same places.
Chicago Area and Illinois River Valley Also Soaked
The Chicago metro area is also in line for a significant soaking. Chicago is forecast near 2.3 inches and Joliet about 2.2 inches. Along the Illinois River Valley, LaSalle is projected near 2.6 inches and Galesburg about 2.4 inches.
Farther south and east, totals drop off. Macomb is near 1.6 inches, Peoria about 1.5 inches, Bloomington–Normal around 1.4 inches, and Pontiac and Kankakee each near 1.3 inches. Havana is close to 1.2 inches. In western Illinois, Quincy is projected near 1.4 inches and Jacksonville about 1.0 inch.
Lighter Totals for Central and Southern Illinois
Across central and southern Illinois, rain totals are expected to be much lighter. Springfield and Champaign are each forecast near 0.9 inch, and Decatur is around 0.8 inch. Charleston and Olney are near 0.6 inch, and Carlinville, Effingham and Vandalia are about 0.5 inch.
In southern Illinois, Carbondale is projected near 0.9 inch, McLeansboro about 0.8 inch, and Mount Vernon and Marion around 0.7 inch. Sparta and the St. Louis metro area are near 0.6 inch. Just across the Ohio River, Paducah is forecast near 1.1 inches.
Timing the Waves of Rain
The rain will come in several waves instead of one continuous storm. Wednesday brings the first round, mainly north of Springfield, with soggy conditions for Peoria, Bloomington, the Quad Cities, Rockford and Chicago.
On Thursday, a second wave moves across the northern half of Illinois, adding to totals where the ground is already wet. By Friday, the rain shifts into the southern half of the state, reaching Springfield, Decatur, Champaign, Effingham, Mount Vernon and Carbondale.
Flooding Concerns in the North
With 2 to 4 inches, and locally up to 5 inches, falling across northern Illinois, ponding on roads, standing water in low-lying areas and rising creeks and streams are all possible. The Rock River, Pecatonica River, Kishwaukee River and Illinois River basins could see water levels rise over the next several days.
Drivers should slow down on wet roads and never try to cross flooded roadways. Homeowners should clear gutters and storm drains and make sure sump pumps are working.
No Severe Weather Expected
There’s some good news in this forecast: no severe weather is expected. The main concern is simply the amount of rain, not damaging winds, hail or tornadoes. Even so, heavy downpours can quickly cut visibility and make travel difficult, especially during the morning and evening commutes.
For continuing coverage of heavy rain in Illinois and weather developments across the Midwest and the United States, visit diamondprowl.com.
