A fast moving arctic cold front brought dangerous conditions to portions of the area. Rain, mixed with freezing rain and sleet moved into western Illinois during the morning, then as a cold front moved in from the west during the mid morning, the rain switched to snow. Strong winds and falling temperatures behind the front caused wet roads to quickly freeze.  Snow fell for several hours after the change over and became heavy at times, with widespread 2 to 6 inches of snowfall. Winds behind the front were 25 to 35 mph with gusts up to 45 mph during the afternoon and evening causing blowing snow in open areas. Whiteout conditions were seen in open areas, and some areas experienced periods of near blizzard conditions, especially across east central and  northeast Iowa. Significant drifting snow continued into Feb. 5.  Wind chills dropped to 5 below to 15 below zero late Thursday night and Friday morning along and north of I-80.
Key impacts: transportation delays, traffic accidents, and road closures.

Winter Storm in STEPHENSON, ILLINOIS
From 04-FEB-21 08:00:00 to 04-FEB-21 19:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Rain and wintry mix started the day, leading to snow (heavy at times), where snowfall reports ranged from 3.4 inches by a CoCoRAHS observer near Winslow to 5.1 inches by the COOP observer in Freeport.

Winter Storm in JO DAVIESS, ILLINOIS
From 04-FEB-21 08:00:00 to 04-FEB-21 19:00:00 (CST-6)
Reported by: COOP Observer

Rain and wintry mix started the day, leading to snow (heavy at times), where between 3 and 6 inches of snow fell throughout Jo Daviess County, with 4.5 inches reported in Elizabeth. Strong winds were also noted in the afternoon, with a peak gust at 42 mph reported at 3 NNE Stockton.

Winter Storm in CARROLL, ILLINOIS
From 04-FEB-21 08:00:00 to 04-FEB-21 19:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Rain and wintry mix started the day, leading to snow (heavy at times), where trained spotters reported between 3.4 inches in Milledgeville to 4.0 inches in Chadwick.

Winter Storm in WHITESIDE, ILLINOIS
From 04-FEB-21 08:00:00 to 04-FEB-21 19:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Rain and wintry mix started the day, leading to snow (heavy at times), where snowfall reports ranged from 2.0 inches of snow in Sterling to 3.0 inches by the COOP Observer in Morrison and Prophettstown.

Winter Storm in ROCK ISLAND, ILLINOIS
From 04-FEB-21 08:00:00 to 04-FEB-21 19:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Rain and wintry mix started the day, leading to snow (heavy at times), where snowfall reports ranged from 2.5 inches by a train spotter 1 mile south southwest of Cordova to 3.7 inches as the official NWS observation at the Moline-Quad Cities Airport. The peak wind gust measured at the Moline Quad Cities was 53 MPH.

Winter Storm in HENRY, ILLINOIS
From 04-FEB-21 08:00:00 to 04-FEB-21 19:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Rain and wintry mix started the day, leading to snow (heavy at times), where reports ranged from 1.3 inches  by a COOP observer 1 mile east of Kewanee to 3.5 inches by a trained spotter 1.9 miles southeast of Coal Valley.