textproduct: Central Illinois

KEY MESSAGES

- There is a Slight Risk (Level 2 of 5) for severe weather for areas east/southeast of a Jacksonville to Havana line late tomorrow morning into the evening hours. All hazards are possible. - Cooler weather returns this weekend with a very low chance (20% or less) of light snow. On Monday morning, there is a 30-60% chance of apparent temperatures less than 10 degrees.

UPDATE

Issued at 817 PM CST Wed Feb 18 2026

Made a couple forecast updates for the overnight and morning hours. Low level moisture will rapidly increase tonight as low 50s dewpoints over southern IL surge north. As this occurs, a subtle shortwave currently over eastern KS will approach. Recent CAM runs have shown isolated to scattered convection developing over east central IL, primarily in a 06-12z window. Added some 20-40% PoPs to account for this. Increasing moisture advection will also cause in increase in low clouds and fog as well, and added a mention of areas of fog, primarily southeast of I-55 for late tonight and Thursday morning. Will need to watch fog trends later as some guidance shows dense fog developing after 10z and a Dense Fog Advisory may eventually be needed for portions of the CWA.

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DISCUSSION

Issued at 205 PM CST Wed Feb 18 2026

Sunny skies and breezy winds have helped to lift temperatures to the upper 60s with some sites reaching 70, challenging record warmth. Winds have been breezy with gusts to 20-30 mph today out of the west. The influx of dry air and strong mixing has allowed dew points to tank in northwestern portions of the forecast area. This combination lines up well with the Red Flag Warning area which remains in effect (see Fire Weather section below for more details). Temperatures will warm to the mid to upper 60s again on Thursday, with convective development likely limiting potential for records.

Westerly winds shift to southerly tonight as the strong low pressure system to our north tracks further northward. Another low pressure system in the elongated trough moves into the Central Plains Thursday morning and then tracks northeastward. Models, especially the hi-res models, have largely removed any potential of overnight rain, with conditions predominantly dry through mid- morning Thursday. There is variation in model timing, but late morning through the afternoon appears to be most favorable for the development of scattered showers and thunderstorms which start out as discrete storms and possible supercells. Later in the afternoon organization into a broken line is more likely with the storms towards eastern portions of the coverage area. The Day 2 SPC severe weather outlook has had a small westward expansion of the slight risk (level 2 of 5) area east/southeast of a line from Jacksonville to Havana with continuation of 5% tornado and 15% hail/wind areas. The environment continues to show very strong bulk wind shear of 50-75 kts, while CAPE varies among models but generally resides around 500-800 J/kg. While heavy rain may accompany thunderstorms, no training is anticipated and QPF is limited, so no flooding issues are projected.

Some models (such as the 18Z HRRR) break up the storm development into two phases with the first phase midday to early afternoon as a SSW to NNE oriented line moving towards Indiana, and the second phase late afternoon into the early evening as a NNW to SSE oriented line forming near the northern edge of the coverage area and tracking towards Chicago. Slight variations in position exist across the models. PoPs are somewhat limited through the day (peaking around 50-60% most places) because of the broken nature of these cells.

Strong cold air advection follows behind this system, sending temperatures much lower for the weekend, with highs dropping to the mid-30s by Sunday. Models have trended much weaker for precipitation potential Saturday, with only a slight chance of non-impactful snow remaining. Northwesterlies continue to bring cold air in late weekend, with Monday morning wind chills having a 30-60% chance of dropping below 10F. Dry weather begins next week, with a warming trend towards midweek.

PAH

AVIATION

(For the 00z TAFs through 00z Thursday Evening) Issued at 510 PM CST Wed Feb 18 2026

MVFR to IFR ceilings and visibilities are expected to develop along a warm front tonight over east central IL, then expand northwest past the I-55 corridor toward 12z. As of now confidence is low that KPIA will see the lower conditions so kept out of their TAF. Category is forecast to improve back to VFR by late morning/midday. A couple rounds of scattered storms are expected Thursday afternoon, but with low coverage (30% or less) and low confidence on exact timing opted to cover storms with a blanket PROB30 during the afternoon. If a terminal is impacted brief drops to IFR and gusty/variable winds will occur. Light winds through tonight will increase by late morning from the southeast, gusting near 20 kt at times.

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CLIMATE

Issued at 252 PM CST Tue Feb 17 2026

Record high temperatures for Wednesday and Thursday:

Location Wednesday Thursday ======== ========= ========= Bloomington 72 (2017) 70 (1930) Champaign 70 (2017) 68 (2017) Charleston 68 (1961) 72 (1930) Decatur 70 (1911) 66 (1930) Lincoln 67 (2017) 71 (1930) Olney 72 (1961) 72 (1930) Peoria 68 (2017) 71 (1930) Springfield 68 (2017) 71 (2017)

Geelhart

ILX WATCHES/WARNINGS/ADVISORIES

None.