textproduct: Central Illinois

KEY MESSAGES

- There is a Marginal Risk (level 1 of 5) for severe weather west of I-57 tonight. The primary risk will be isolated damaging wind gusts between 9pm and 3am.

- Another round of strong to potentially severe thunderstorms may accompany a strong cold front late Thursday afternoon and evening. The most recent SPC outlook highlights locations along and south of the I-72 corridor.

- Much cooler weather will settle into the region this weekend, potentially resulting in frost both Saturday and Sunday mornings.

DISCUSSION

Issued at 127 PM CDT Tue Oct 13 2026

A slow-moving cold front has sagged into the region early this afternoon...with 18z/1pm analysis showing the boundary extending from southern Lake Michigan to just north of Kansas City. To the south of the front, record warm temperatures in the upper 80s and lower 90s prevail across south-central Illinois into much of Missouri. Meanwhile to the north, readings have dropped into the 60s across central/northern Iowa. Aside from isolated convection on the cool side of the boundary in western Iowa, the regional radar mosaic is presently mostly blank. This will change after dark as a 30-40kt 850mb jet streak oriented from Texas to Kansas triggers widespread convection near the front across eastern Kansas into northern Missouri/southern Iowa. This activity will gradually spread E/NE into parts of central Illinois late this evening into the overnight hours, bringing the risk for isolated damaging wind gusts and localized downpours. The CAMs have generally been trending slower with convective arrival east of the Mississippi River, so the primary time frame for a couple strong storms will be from about 9pm through 3am. After that, instability will wane and the scattered storms will gradually weaken toward sunrise.

The frontal boundary will drop further south on Wednesday, focusing the most widespread showers/storms along and south of I-70 during the morning and early afternoon. After that, rain chances will steadily decrease from north to south across the area as the front sinks south of I-70. High temperatures on Wednesday will be considerably cooler than today, but still above normal for this time of year...ranging from around 70 degrees from the Peoria area northward to the lower 80s south of I-70.

After a lull in precip chances Wednesday evening, a short-wave trough interacting with the tail end of the departing front will bring an increased wave of convection late Wednesday night into Thursday morning. While parameters do not support severe weather at that time, it appears this will be the wettest period of the upcoming forecast with widespread showers and a few thunderstorms lingering through midday Thursday. After that, we will need to keep a close eye on radar and instability trends, as models suggest the front will lift north of the region and showers will become much less numerous. If partial clearing and sufficient destabilization can occur in the warm sector Thursday afternoon/evening, strong 0-6km bulk shear of 40-50kt may provide the fuel for strong to severe thunderstorms along an advancing cold front. CAMs that extend to that particular time frame such as the 3km NAM and RRFS are not particularly robust with storm development, but think this may be underdone given the strength of the shear and the approaching front. SPC currently highlights locations along/south of I-72 with a Marginal Risk (level 1 of 5) for severe. Stay tuned to later forecasts for additional details.

Once the cold front passes, a much cooler airmass will arrive by the end of the week. High temperatures will drop below normal into the upper 50s/lower 60s for both Friday and Saturday before rebounding nicely back into the 70s by next Monday/Tuesday. The coolest night of the forecast period will be Friday night when 12z Oct 13 models show surface ridging overhead...leading to excellent radiational cooling and the potential for frost. The 00z Oct 13 LREF shows a 5-15% chance of lows dipping below 32F along/north of I-72. Temps will be a few degrees warmer Saturday night as the high moves east and southerly return flow commences:however, there is a 5-10% chance of lows below 32F east of I-57.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1219 PM CDT Tue Oct 13 2026

A cold front will slowly sag south across the area today and tonight. SW to W winds ahead of the front today will become light and variable within the frontal trough, then set up out of the NE behind the front Wednesday. Meanwhile, scattered thunderstorms are expected late this evening and overnight with the latest guidance favoring storms impacting the northern most terminals (PIA/BMI) tonight. Additional showers and storms are expected during the day Tuesday with the greatest coverage expected near and south of I-72.

CLIMATE

Issued at 1220 AM CDT Tue Oct 13 2026

Record high temperatures:

Location Tuesday Latest 90 deg. High ======== ======= =================== Bloomington 91/1899 October 15, 1899 Champaign 86/1989 October 14, 1899 Charleston 87/2017 October 15, 1897 Decatur 90/1899 October 15, 1938 Jacksonville 91/1899 October 30, 1950 Olney 93/1928 October 22, 1953 Peoria 88/1899 October 15, 1897 Springfield 88/1975 October 12, 2026

ILX WATCHES/WARNINGS/ADVISORIES

None.