An upper-level wave and its associated weak surface low tracked slowly northward from the Ozarks around midday January 2nd into northern Indiana by the early morning of January 3rd. The system brought widespread light snow to central Illinois, with amounts of 2 to 5 inches common east of the Illinois River and north of I-70.
Every event with a place to put it; 3 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS ILX wrote it up.
An upper-level wave and its associated weak surface low tracked slowly northward from the Ozarks around midday January 2nd into northern Indiana by the early morning of January 3rd. The system brought widespread light snow to central Illinois, with amounts of 2 to 5 inches common east of the Illinois River and north of I-70. As the wave slowed and pivoted out of the region, a mesoscale snow band persisted across a small portion of central Illinois until the pre-dawn hours of January 3rd. As a result, much heavier snowfall totals of 5 to 10 inches were focused across Macon, DeWitt, and Piatt counties.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Lincoln, IL wrote its last area forecast discussion before the first event at Jan 2, 5:20 PM CST, 1 hour 55 minutes earlier.
Area Forecast Discussion National Weather Service Lincoln IL 520 PM CST Sat Jan 2 2021 .SYNOPSIS... Issued at 305 PM CST Sat Jan 2 2021 Light drizzle will continue to impact the region through the evening as the next weather system moves through the area tonight. This will bring another chance for accumulating snowfall to location se of the Illinois River Valley, with upwards of 2 inches by Sunday morning. The best chance for snowfall exists across eastern Illinois, while locations in central Illinois will see upwards of 1 inch. Cloudy skies will also persist through the overnight, along with the return of dense fog conditions northwest of the I-55 corridor. Behind this system, High pressure arrives to end the weekend and begin next week. && .SHORT TERM...(This evening through Sunday) ISSUED AT 305 PM CST Sat Jan 2 2021 Low clouds continue to impact the Midwest as more moisture is ushered into the region tonight. This is evident on radar as light bands of precip are currently pushing through the state. As this evening progresses, the upper level Low pressure system will track towards the Ohio River Valley from the lower Mississippi River Valley. This will track mostly snowfall through the region overnight, as temperatures will drop below freezing after sunset. Some light mixed precip could occur to begin, south of the I-70 corridor, as temps are slightly above freezing...however this will change to snowfall as the Low passes south of the area. With winds coming out of the ne currently, low clouds are expected to linger throughout the overnight into the morning. This will finally begin to shift out of the area Sunday as winds shift to the west behind Low pressure passage and exit. As with most winter time clouds, expecting lingering low ceilings through Sunday morning. Issued a Dense Fog Advisory for tonight through Sunday morning, as these clouds are expected to persist throughout the period. With the light winds lingering into Sunday morning, will have the chance to hold the clouds in place. Only question this afternoon was the possibility of clouds increasing as the Low pressure slides through the region. Thinking was that it will be far enough southeast that the low clouds and excessive moisture would be enough to hold fog in place. This system will slide out of the region Sunday, allowing for the return of High pressure to the area. && .LONG TERM...(Sunday night through Saturday) ISSUED AT 305 PM CST Sat Jan 2 2021 Weak High pressure slides through the Midwest late Sunday into the start of the week. However there is some model depiction of another weak frontal system to track through the upper Midwest Monday night into Tuesday. This could swing another weak frontal boundary through the region late Monday. The big question here will be if there is enough moisture to spark a few showers throughout the area. The best energy looks to be east of the Midwest, however some models hint at a chance for precip. Currently left the mention of any precip out of the forecast, as this is a weak system, and not expected to bring any precip to the area. Behind this boundary, a stronger High pressure system slides into the area from the south. Unfortunately, this week's setup really will be a mixed bag. Heading into mid-week, a large-scale Low pressure system develops across the central Plains and tracks slowly eastward. This will bring the next weather maker to the Midwest Wednesday evening through Thursday. However, models do have some hint that this system might slide south of the area, so there is some detail that needs to be worked out over the next couple of days. If High pressure takes dominance over eastern Canada mid-week, this will help to push the system south of the Midwest Wednesday night, moving the best chance for precip across the se US. If High pressure cannot hold control, then this system is likely to slide into the Tennessee Valley, which would provide some precip to southern Illinois during the second half of the week. Models have differing solutions heading into the weekend, so this will need to be held of for now. But High pressure looks to take control again, as of now Saturday looks dry. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 519 PM CST Sat Jan 2 2021 While widespread ceilings of a few hundred feet are present over much of central Illinois, areas from KCMI east and south have recently seen MVFR ceilings rise over 2,000 feet at times. Deterioration there is expected later this evening as light snow moves into the area, reducing visibilities down below a half mile. Elsewhere, there has been some periods of light snow or drizzle recently, but more widespread light snow is expected toward mid evening. No real improvement in ceilings expected through the period, though perhaps getting closer to 1,000 feet at KPIA/KBMI westward Sunday afternoon. && .ILX WATCHES/WARNINGS/ADVISORIES... Dense Fog Advisory until noon CST Sunday for ILZ027>031-036>038- 040>042-047>051. && SYNOPSIS...Baker SHORT TERM...Baker LONG TERM...Baker AVIATION...Geelhart
Hazardous Weather Outlook National Weather Service Lincoln IL 403 PM CST Sat Jan 2 2021 ILZ027>031-036>038-040>042-047>051-031200- Cass-Fulton-Knox-Logan-Marshall-Mason-McLean-Menard-Morgan-Peoria- Sangamon-Schuyler-Scott-Stark-Tazewell-Woodford- 403 PM CST Sat Jan 2 2021 ...DENSE FOG ADVISORY IN EFFECT UNTIL NOON CST SUNDAY... This Hazardous Weather Outlook is for portions of central Illinois and west central Illinois. .DAY ONE...TONIGHT... Areas of dense fog will develop this evening and continue through tonight. In addition, light snow accumulations up to an 1 inch are expected tonight, mainly after 7 pm. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY... Areas of dense fog will continue through Sunday morning. There is a chance for light snow accumulations Wednesday night. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated through tonight. ILZ043>046-052>057-061-031200- Champaign-Christian-Coles-De Witt-Douglas-Edgar-Macon-Moultrie- Piatt-Shelby-Vermilion- 403 PM CST Sat Jan 2 2021 This Hazardous Weather Outlook is for portions of central Illinois and east central Illinois. .DAY ONE...TONIGHT... Snow accumulations between 1 and 2 inches are expected tonight, mainly after 8 pm, and will diminish by early Sunday morning. Untreated roads could become slippery. Areas of fog will continue throughout tonight, with locally dense fog possible. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY... Areas of fog, locally dense, will continue through Sunday morning. There is a chance for light snow accumulations Wednesday night. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated through tonight. ILZ062-063-066>068-071>073-031200- Clark-Clay-Crawford-Cumberland-Effingham-Jasper-Lawrence-Richland- 403 PM CST Sat Jan 2 2021 This Hazardous Weather Outlook is for portions of east central Illinois and southeast Illinois. .DAY ONE...TONIGHT... Light snow accumulations less than 1 inch are possible tonight. Areas of fog will develop this evening and continue tonight, with locally dense fog possible. Minor flooding is occurring on the Little Wabash River at Clay City. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY... Patchy fog, locally dense, will continue through Sunday morning. Minor flooding is forecast to continue on the Little Wabash River at Clay City through Monday morning. There is a chance for light snow accumulations Wednesday night. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated through tonight. 37
The national radar mosaic for the moment the first event began.
3 heavy snow. Local standard time, as filed.
Numerous observers measured 5 to 8 inches of snow across Macon County...including 8.0 in Decatur and Mt. Zion, 7.0 1 mile south of Oreana, and 6.2 in Forsyth. Roads became hazardous and snow-covered.
Numerous observers measured 6 to 8 inches of snow across DeWitt County...including 6.0 1 mile southwest of Clinton. Roads became hazardous and snow-covered.
Numerous observers measured 7 to 10 inches of snow across Piatt County...including 9.8 in Cisco and 8.0 in Monticello. Roads became hazardous and snow-covered.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2021Every state in 2021This day in weather historyWarnings in Illinois, January 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 936683, 936682, 936684.