textproduct: Central Illinois

KEY MESSAGES

- Dangerous cold persists through tonight across central IL, with wind chills as cold as 12 to 22 degrees below zero at times north of I-70.

- Areas of blowing and drifting snow are possible late tonight into early Monday afternoon. This could result in localized, sharp visibility reductions, as well as drifting of snow onto roadways. The greatest impacts will be on east-west oriented roads due to south southwest winds gusting 25 to 30 mph on Monday.

- A warming trend is expected this week, with highs in the mid 40s to mid 50s on Thursday.

DISCUSSION

Issued at 230 PM CST Sun Dec 14 2025

We continued the cold weather advisory for a good chunk of central IL through 6 am Monday morning. Continued to side with colder lows this evening in the single digits below zero and a few spots in east central IL approaching 10 below due to clear skies, light winds and fresh snow pack. Temps to increase overnight with temps in the single digits above zero by daybreak Monday as south winds gradually increase. We will issue a Special Weather Statement addressing the blowing and drifting snow and reduced visibility concern late tonight after 4 am into early Monday afternoon with SSW winds increasing with gusts 20-30 mph on Monday, though diminishing by late Mon afternoon.

The 20Z/2 pm surface map shows strong 1041-1043 mb arctic high pressure over central/northern MO and west central IL and providing sunny skies but very cold conditions. Temps at 2 pm were in the single digits over central IL and 10-13F from highway 50 south where little or no snow pack. Winds have gradually lightened up during the day as strong high pressure built into west central IL. But still some biting cold wind chills of 5 to 15 below zero with Champaign the coldest wind chill of 16 below.

Arctic high pressure to drift into the mid MS and lower Ohio river valley by midnight and into the Gulf Coast and Southeast States Monday afternoon. As ridge shifts se of IL, will see SSW winds increasing later tonight with brisk conditions on Monday with gusts 20-30 mph. This will likely cause some blowing and drifting of our fresh snow pack over central IL (deeper snow pack from Macomb to Springfield to Mattoon northeast) on Monday especially on east- west oriented roadways along with sudden reduced visibilities. Highs Monday in the mid to upper 20s over central and ne CWA and lower 30s southeast IL and west central IL. A disturbance moving se over the Great Lakes on Monday to give more clouds to ne CWA though still a partly to mostly sunny day with ample sunshine again over sw CWA. Lows Mon night in the mid to upper teens, with lower 20s in west central IL and far southeast CWA.

A semi-zonal upper air flow during Tue and Wed to bring in more of a Pacific air mass into IL for mid week. Continue SSW flow on Tue though not as strong as Monday with not as tight of pressure gradient. Highs Tue closer to normal in the mid 30s to lower 40s. Highs near 45F over far SW CWA near Winchester/Scott county and Flora/Clay county. A bit milder Wed with highs mostly in the 40s, with some upper 30s from BMI and CMI northeast.

A strong storm system off the Pacific Northwest to eject a strong surface low pressure to upper MS river valley by dawn Thu and pass ne of the Great Lakes by sunset Thu, while pushing a cold front east across IL during Thu. This will likely bring a period of rain showers to area late Wed night and Thu with WPC moderate QPF of 0.35 to 0.60 inches. Strong SW winds ahead of this front could gust to 35 mph or higher. Thu appears to be the warmest day this week with highs in the upper 40s northern CWA and mid 50s in southeast IL. Weak high pressure moves into IL on Friday returning dry and colder weather. Models have trended colder on Fri with lows Thu night in the teens (upper single digits by Galesburg). Highs Fri in the upper 20s/lower 30s which is cooler than normal.

Temperatures to bounce back on on Saturday with breezy SSW winds, with highs in the mid 40s to lower 50s. Though another cold front to pass se through IL late Sat and Sat evening bringing next chance of precipitation and cooler temps for next Sunday (highs in upper 30s/lower 40s central IL and mid 40s southeast IL).

07

AVIATION

(For the 18z TAFs through 18z Monday Afternoon) Issued at 1122 AM CST Sun Dec 14 2025

VFR conditions will persist through this evening as surface high pressure settles directly over the central Illinois terminals, keeping skies clear and winds light and variable. The gradient wind will begin to pick up beyond 06z/Midnight as high pressure drifts east of the region. At that time, winds will shift southerly and gradually increase to 10-15 kts by Monday morning with occasional gusts between 20-25 kts.

Given the fresh snowpack and blustery south winds into Monday morning, we have introduced BLSN (blowing snow) into this round of TAFs, but opted against including LLWS (low-level wind shear). If surface gusts do not increase as quickly as anticipated, then we may need to add LLWS at KPIA, KSPI and KBMI sometime between 12z-16z, for 40 kts and heights around 2 kft.

MJA

ILX WATCHES/WARNINGS/ADVISORIES

Cold Weather Advisory until 6 AM CST Monday for ILZ027>031- 036>038-040>046-048-051>057-061>063.