textproduct: Central Illinois

KEY MESSAGES

- Two areas of snow are forecast this morning, one north of I-74 and the other south of a Shelbyville to Paris line. In both areas, the probability of over one inch of snow is less than 20%.

- Temperatures will oscillate throughout the week, but generally feature highs in the 20s or 30s. The exception is Friday, when highs are forecast to reach the 40s. A more appreciable warmup is expected next week, with a chance (40-70%) for highs in the 50s.

DISCUSSION

Issued at 231 AM CST Tue Feb 3 2026

*** TODAY ***

A broad shortwave trough is approaching from the west and will offer snow chances today. Notably, there is a narrow band of snow ongoing just north of the ILX CWA. This band traversed IA during the late evening, and extended roughly from the Quad Cities to Kankakee, IL as of 0745z/145am. Visibility within this band has dropped as low as 1/2 mile at times, and in areas where it is most persistent a localized 1-2" of snow could occur. The strength of this band has been aided by steep lapse rates within the dendritic growth zone, with the 00z KDVN sounding sampling lapse rates approaching 8 degC/km within the DGZ. Guidance has had a poor handle on the evolution of this feature. While some models had hints of snow north of I-74 this morning, none had forcing of this magnitude, and even short-term analysis fields from the RAP are not accurately catching on to where the more robust forcing is ongoing.

This leads to a low confidence forecast this morning in terms of how far southeast this band tracks, as well as its timing. Much of the short-term forecast for this feature has been driven by extrapolation of radar trends. The most recent motion seems to be ESE rather than SSE, which should keep the core of the band north of the ILX CWA. Still, areas near and especially north of the I-74 corridor should be on the lookout for a quick round of snow that could coat road surfaces and temporarily reduce visibility this morning.

Further south, broader forcing associated with this trough is evident in IR satellite as a broad region of mid/upper level clouds is present over the mid-MS Valley. In particular, there are slightly cooler cloud tops evident extending in areas generally near the I-70 corridor through MO and IL. Radar also shows weak radar returns (not yet reaching the surface) beneath this cloud band. This is the area where precip development is expected into the day today, with some models suggesting weak fgen forcing in addition to low-level WAA. Once the forcing overcomes dry low- level air, expect a band of snow to develop in this region by mid to late morning, quickly shifting east in time and largely departing the ILX CWA by early afternoon. While banded snow is still expected with this system, the placement is largely expected to be focused east of our area. Some minor snow accums are forecast, mainly in areas south/east of Coles County, but the latest probabilistic guidance has just a 10-20% chance of over an inch in those areas.

*** TONIGHT INTO NEXT WEEK ***

A sfc high pressure is expected to settle in over the Upper Midwest tonight, resulting in light northeasterly low-level flow persisting across IL. The cloud cover forecast has trended toward greater sky cover overnight, as that low-level flow advects moisture off Lake Michigan. This is captured well in RAP/NAM 925mb RH fields, which handled well in other recent lake moisture advection events. The key takeaway from all of this is that the low temp forecast trended a few degrees warmer, with lows now just above 10 degF (closer to 15 degF south of I-70) as opposed to in the single digits. If any areas do manage to stay mostly clear, the lower temps are still possible. The most likely area for this would be west of the IL River. With winds on the light side, minimum wind chill values for tonight/Wed AM should stay above zero.

Minimal weather impacts are forecast during the latter half of the work week. The synoptic pattern continues to feature persistent, amplified ridging out west, with troughing over the eastern US. A potent upper low is progged to approach the Hudson Bay Thurs night, leading to a deep sfc low in that same region (well north of the Great Lakes). Locally, this will lead to the development of southwesterly flow on Thurs, which then persists into early Fri AM until the associated cold front swings through the region. That will result in a modest warming trend, with Thurs highs in the 30s (upper 30s west of IL River, low 30s east of I-57), then upper 30s to mid 40s on Fri. Most locations have not experienced 40 degree temps since mid-January. That persistent southwesterly flow will also result in seasonably mild temps Thurs night, with lows only in the mid/upper 20s. Precip from this system is still expected to stay northeast of the ILX CWA, with just a 10% chance of precip north of a Bloomington to Paris line, per the latest LREF.

Temps cool slightly following the cold FROPA on Fri, returning to near or slightly below seasonable values, with forecast highs in the 30s. The influence of a broad sfc high should keep the area dry through the day Sat, but there could be a clipper system to offer precip chances late Sat night into Sun. This is a relatively new feature that has shown up in some of the deterministic models, and isn't yet producing a signal in ensemble PoPs. For now it's just something to monitor, and I mention it simply to say that we cannot confidently say the weekend will be dry, despite the current gridded forecast suggesting so.

Into next week, the synoptic pattern finally start to shift, with ridging moving east and upper level height rises occurring across the Midwest. Ensemble probabilities continue to suggest a 40-70% chance for highs in the 50s each day Tues-Thurs of next week (Feb 10- 12).

Erwin

AVIATION

(For the 18z TAFs through 18z Wednesday Afternoon) Issued at 1113 AM CST Tue Feb 3 2026

A band of light snow will continue to drift across east-central Illinois this afternoon. Recent observations associated with this snow band have indicated a brief dip to MVFR at KBMI, mainly due to ceilings in the 1-3 kft range. Once the band passes, the dominant ceilings returns to around 10 kft. The KCMI terminal has the next best chance of seeing lower ceilings as a result of this snow band, and this has been annotated with a brief tempo group from 19z-21z.

By late tonight, a shallow fetch of moisture from Lake Michigan could advect southwestward toward the KCMI & KDEC terminals. There is currently a low (30-50%) chance for MVFR ceilings to arrive at these sites between 03z-09z.

Elsewhere across central Illinois, VFR conditions are currently in place and expected to persist through the remainder of this TAF period amid a light north wind.

MJA

ILX WATCHES/WARNINGS/ADVISORIES

None.