textproduct: Central Illinois

KEY MESSAGES

- A chilly weekend is in store with highs in the 30s and overnight lows in the teens. Wind-chill values will dip into the single digits both tonight and Sunday night.

- An upper-level disturbance will bring a few snow flurries to parts of central Illinois today and tonight. There is a low probability (10-30% chance) for measurable snowfall along and northeast of a Bloomington to Paris line.

DISCUSSION

Issued at 1243 AM CST Sat Feb 21 2026

The primary forecast concern for today is the potential for afternoon flurries. Early this morning, mid-level water vapor imagery shows a strong shortwave trough lifting across the Plains. Short-term models agree this feature will cross the mid- Mississippi Valley by midday.

However, the 00z RAOB indicates very dry air ahead of this shortwave, which should limit surface precipitation this afternoon as much of the system's energy will be used to moisten the atmospheric column. Nevertheless, flurries have been included in the forecast as a safeguard against the atmosphere saturating more efficiently than model soundings suggest. Even with afternoon temperatures reaching the upper 30s, the surface wet-bulb temperature will be cold enough to support mainly snow if precipitation does reach the ground.

As the night progresses, a shortwave will begin to phase or consolidate with an upper low moving toward the Great Lakes. This consolidation, combined with anomalous high pressure building over the Northern Plains and a developing Nor'easter, will cause the surface pressure gradient to rapidly tighten. Consequently, winds will increase. Snow showers are also possible across northeast and east-central Illinois due to increasing moisture and synoptic ascent near the upper low, with lake effect processes potentially adding to the snow chances in that area. However, the most significant impact will be the return of single-digit wind chill values overnight and into Sunday morning.

Temperatures will be colder than normal for late February on Sunday and Monday, with daily averages expected to be 5-10 degrees below seasonal norms. Highs will be around 30 degrees, and lows will drop into the teens.

However, a rapid shift toward milder weather is expected to begin Monday night. A broad ridge axis will push across the central U.S., causing mid-level heights to increase quickly. This pattern will usher in a notable warming trend through the middle of next week. Warmer air will be advected into the Midwest, aided by compressional warming from down slope flow off the Rockies. The latest NBM guidance predicts afternoon highs in the 40s by Tuesday and climbing into the 50s by Wednesday.

A frontal system is expected to push through the area as a strong shortwave drops across the Mid-Mississippi Valley, causing mid- level heights to fall from Wednesday into Thursday. This is the period when our next potential precipitation event is anticipated. Currently, the NBM guidance suggests a weak QPF signal across much of Illinois, but this may be an artificially low projection due to inconsistencies in the timing and placement of the storm track across the various models.

Quiet and mild weather will return by the end of next week as a ridge of high pressure settles in behind the departing mid-week storm system. Temperatures for next Friday and Saturday look to be squarely in the 50s.

MJA

AVIATION

(For the 12z TAFs through 12z Sunday Morning) Issued at 530 AM CST Sat Feb 21 2026

Mid-level clouds are increasing from the west with an area of MVFR low stratus just north of here. Short-term guidance is struggling to depict the evolution of the low stratus. However, based on its movement and areal coverage it appears increasingly likely that it will continue spreading south over the next several hours and impact northern airfields. Confidence is low on how long it sticks around and therefore future updates will be needed to better pinpoint it. Another round of low stratus is possible toward the end of the TAF period as an upper-level disturbance swings through the Great Lakes Region overnight. Northwest winds become breezy this afternoon and are expected to remain elevated through tonight

NMA

ILX WATCHES/WARNINGS/ADVISORIES

None.