textproduct: Central Illinois

KEY MESSAGES

- Patchy freezing fog is possible in east-central IL early this morning. Isolated slick spots could develop.

- A wintry mix of snow and freezing drizzle is possible (10-20%) late tonight into Friday morning along and north of a Bloomington to Paris line. If precip does occur, it could lead to slick surfaces.

- It will be breezy on Friday, with wind gusts of 25 to 35 mph following a cold frontal passage. Winds will be much lighter on Saturday.

- Above normal temperatures return early next week. There is potential for highs above 50 each day Monday through Wednesday, with the best chance being on Tuesday (50-80%).

DISCUSSION

Issued at 311 AM CST Thu Feb 5 2026

*** EARLY MORNING FREEZING FOG IN EAST CENTRAL IL ***

Multiple clipper systems will pass by to the north over the next 48 hours, offering low chances for wintry precip as they do. At the start of the period, a weak sfc high was located near the Ozarks, with a sfc ridge axis extending into IL. As of 08z/2am, lake- enhanced low stratus deck persisted across southeast and far eastern IL (roughly Effingham to Paris and southeast), keeping temps in the mid teens to low 20s. It has also limited fog from developing in these areas. Elsewhere, the approaching clipper is pushing an upper level cloud deck into the region from NW to SE, with areas from Beardstown to Bloomington now beneath the cirrostratus deck. In between these two areas of clouds, clear skies and light winds have allowed temps to fall into the single digits and some fog development has occurred.

Nighttime microphysics satellite imagery suggests this patchy fog (some of which is dense) is most prevalent in east-central IL, between Mattoon and Champaign and eastward. Webcams and observer reports suggest that the fog is variable and relatively shallow, likely most impactful in low-lying areas or areas where the light but persistent SW sfc winds lead to micro-orographic lift. With temps in the teens, freezing fog is a concern in areas where the fog is most persistent, so be on the lookout for patchy slick spots to be associated with the fog this morning. The hope is that as the cirrus shield overspreads the area the fog coverage will start to diminish, but kept a mention of freezing fog in the forecast through sunrise to be safe.

*** PRECIP CHANCES THROUGH FRIDAY ***

An amplified upper ridge extending from the southern Plains towards the Pacific NW will result in a storm track that favors upper disturbances tracking towards the Great Lakes region. The first of two clipper system is expected to swing through the northern half of IL this morning. Forecast soundings don't appear to saturate effectively during the morning hours, so largely kept the CWA dry for this wave (just low PoPs or flurries, mainly north of I-74).

Some model forecast soundings (particularly the NAM suite) have better low-level saturation into this afternoon/eve, so that may be a better opportunity for light snow/drizzle than this morning. Unfortunately, those soundings show potential that the saturated layer stays warmer than -10 degC, introducing some uncertainty as to whether or not cloud ice will be present. A lack of cloud ice favors freezing drizzle (FZDZ) rather than light snow. While this will bear watching, other forecast soundings are drier in the low- levels and the upper level forcing weakens into the evening, so held off on adding a mention of FZDZ to the gridded forecast for this afternoon/eve.

Wave #2 arrives late Thurs night into Fri AM, and the QPF swath tracks a bit further south compared to Wave #1. While not all models have precip into the ILX CWA, there were enough that did to warrant expanding the precip mention to areas from Bloomington to Paris and northward. CAMs suggest a wintry mix as the p-type, and forecast soundings corroborate this output. The forecast soundings suggest a brief period of snow or perhaps sleet at the onset, then a potential transition to FZDZ as the column desaturates from the top-down, the cloud layer warms above -10 degC, and ice nuclei are lost. The latest HREF and REFS both had roughly a 10-15% chance of at least a Trace of ice along/north of that aforementioned Bloomington to Paris line, with those probs increasing slightly as you move north of the ILX CWA.

*** SHORT TERM TEMPS/WIND & WEEKEND OUTLOOK ***

After a cold start this morning, particularly in the cloud-free areas, a modest warming trend is still on track through Fri. There will be a gradient in highs today, ranging from the upper 30s in west-central IL to upper 20s in eastern IL. Partly to mostly cloudy skies tonight combined with persistent SW flow induced by the sfc lows tracking north of our area will result in seasonably mild lows, with values in the mid 20s.

Highs could reach the upper 30s or low 40s on Fri, but cold FROPA occurring mid-morning into the afternoon will make it a challenge for wind chills to climb above freezing. The latest HREF has mean gusts of 30 mph in the post-frontal regime. A sfc high sinks south on Sat, so while temps trend cooler the winds should become lighter. The weekend still looks mostly dry. We've been monitoring the low chance for a clipper to producing precip on Sun, but the few models that had this feature now keep it north of our area. The latest model blend has PoPs near 0% on Sun.

*** EARLY NEXT WEEK ***

A notable warm up is still on track for early next week, with a 50% or higher chance of reaching 50 degF west of a Peoria- Springfield line on Mon, then a 50-80% chance of being above 50 degF area- wide on Tues.

Model timing differences become an issue for pinning down the rain chances next week, but in general, the expectation is that a closed upper low that will be located near Baja California Sun night will eventually progress onto the southern Plains. Whether or not that system is able to become phased with a northern stream wave remains to be seen. Due to the timing differences, ensemble guidance produces a prolonged period with 30-40% PoPs. These will likely be refined and encompass a shorter time frame as the timing differences are resolved. Both the GEFS and EC Ens mean show precipitable water (PWAT) values approaching 1-2 standard deviations above normal with this system, with ens. mean values of 0.70-1.00". That's a promising sign for those hoping for rain to chip away at the ongoing drought. The latest NBM has a 20-30% chance for 1" of rain area- wide through next Friday morning.

Erwin

AVIATION

(For the 12z TAFs through 12z Friday Morning) Issued at 436 AM CST Thu Feb 5 2026

Conditions are expected to be VFR through much of the period, although scattered clouds around 2500 feet today could occasionally produce MVFR ceilings. Snow chances today seem to be focused primarily north of I-74, so removed the PROB30 mention of snow. Another chance of precip exists at KBMI/KCMI towards the very end of the period. This too may track just north of the terminals, but will be one to monitor closely as the precip could be in the form of freezing drizzle. If this precip were to occur, the most likely timing would be 11-15z Fri. Winds today will be out of the southwest, around 10 knots, then winds gradually turn to westerly tonight.

Erwin

ILX WATCHES/WARNINGS/ADVISORIES

None.