A potent low pressure system tracked from eastern Oklahoma and western Missouri into northern Illinois and the Great Lakes region, from December 28th to the early morning hours of the 29th. An unseasonably warm and moist airmass interacted with the system to produce heavy mixed precipitation across western Illinois. Heavy snow, sleet accumulations up to 2-4 inches, and a glaze ice amounts over a quarter inch were reported across the region. The ice and strong winds gusting up to 50 mph resulted in widespread downed trees and powerlines, and power outages. The hardest hit areas, with glaze ice amounts of 1/4-1/2 inch, were located along and south of Interstate 80. The highest amounts of combined snow and sleet, in the 3-5 inch range, occurred in northwest Illinois.

Winter Storm in ROCK ISLAND, ILLINOIS
From 28-DEC-15 03:00:00 to 29-DEC-15 01:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Precipitation began as freezing rain and transitioned to sleet and snow during the early evening hours.  Snow and sleet accumulations were 2 to 3 inches in Rock Island and Moline. The official NWS observation at the Moline Quad Cities Airport was 2.5 inches.

Winter Storm in HENRY, ILLINOIS
From 28-DEC-15 03:00:00 to 29-DEC-15 02:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported 0.20 inches of freezing rain in Kewanee. There were no reports of sleet in Henry County but reports from neighboring counties indicate that up to an inch was possible in western portions of Henry County.

Winter Storm in BUREAU, ILLINOIS
From 28-DEC-15 03:00:00 to 29-DEC-15 02:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter near Princeton reported a tenth of an inch of ice accumulation.

Winter Storm in MCDONOUGH, ILLINOIS
From 28-DEC-15 00:00:00 to 28-DEC-15 20:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

The AWOS at Macomb and radar suggest that freezing rain began shortly after midnight and ended around noon when it changed over to all rain.

Ice Storm in HANCOCK, ILLINOIS
From 28-DEC-15 00:00:00 to 28-DEC-15 12:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law Enforcement reported that branches and power lines were down due to ice accumulation in La Harpe.

Ice Storm in HENDERSON, ILLINOIS
From 28-DEC-15 01:00:00 to 28-DEC-15 22:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotters in neighboring counties reported ice accumulations between a sixteenth and a quarter of an inch on trees and power lines.

Winter Storm in WHITESIDE, ILLINOIS
From 28-DEC-15 04:00:00 to 29-DEC-15 02:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotters reported sleet and snow accumulations between 1 to 3 inches.

Winter Storm in CARROLL, ILLINOIS
From 28-DEC-15 05:00:00 to 29-DEC-15 01:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reports between 3 to 4 inches from east to west across Carroll County.

Ice Storm in WARREN, ILLINOIS
From 28-DEC-15 01:00:00 to 29-DEC-15 22:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter, near Monmouth, reported more than a quarter of an inch of ice accumulation with numerous powerlines, power poles, and trees down.

Winter Storm in MERCER, ILLINOIS
From 28-DEC-15 02:00:00 to 28-DEC-15 22:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter in Sherrard reported freezing rain with 4 to 6 inch tree limbs down. The COOP observer in Aledo reported 1 inch of accumulation.

Winter Storm in STEPHENSON, ILLINOIS
From 28-DEC-15 06:00:00 to 29-DEC-15 01:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reports ranged from 2.5 to 3.5 inches of snow and sleet across the county from southeast to northwest.

Winter Storm in JO DAVIESS, ILLINOIS
From 28-DEC-15 06:00:00 to 29-DEC-15 02:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

COOP Observer reported 5.0 inches of sleet and snow accumulation in Stockton and Galena.