textproduct: Central Illinois

KEY MESSAGES

- A stretch of warm weather is expected to begin today and last through Friday, with daily temperatures climbing near 80 degrees. Gusty winds, occasionally reaching 30-40 mph, will accompany this warm period. Blowing dust may reduce visibility wherever early field work is taking place across the region. - This week will be riddled with thunderstorm potential. Tuesday and Wednesday currently exhibit the highest probability (15-30%) of severe weather.

- There is also a potential for substantial accumulative rainfall throughout the week, with our multi-model ensemble predicting a medium (40-60%) chance of exceeding 2 inches through Saturday.

DISCUSSION

Issued at 133 AM CDT Sun Apr 12 2026

A significant warming trend begins today, bringing high temperatures near 80 degrees daily through Friday. This shift is due to a warm front lifting northward across the region, supported by strong low-level warm air advection ahead of an active upper-level low moving inland from the West Coast. Gusty non-thunderstorm wind gusts will occasionally exceed 35 mph throughout today, according to the latest NBM guidance (01z). Blowing dust could become a visibility concern wherever early field work is taking place across the region.

Rain is likely (60-80% chance) this evening, driven by subtle shortwave energy within the broad southwest mid-level flow, a low-level jet, and isentropic ascent. While rainfall amounts are expected to range between a trace to 0.25 inches areawide, locations near and north of the Illinois River, closer to the axis of the low-level jet, could see higher totals ranging from 0.25 to 0.75 inches, according to the latest HREF QPF LPMM guidance (00z).

Monday is expected to be relatively dry. This is due to synoptic scale subsidence following the departing mid-level shortwave and its associated showers, and as height tendencies see a slight increase.

Tuesday's setup remains conditional for widespread, potentially severe, convection, driven by moderate instability from surface temperatures near 85 F, dewpoints in the 60s, and favorable mid- level lapse rates, all coinciding with an intensifying mid- level jet.

However, the synoptic forcing appears somewhat nebulous. The surface front remains north of our forecast area, and there is no strong shortwave lifting across the region. Mesoscale soundings show a "loaded gun" profile, but the trigger mechanism for storm initiation remains unclear into the afternoon hours.

Consequently, significant uncertainty exists regarding the timing and location of storm development, and CAMs may struggle to accurately depict the initiation and evolution of storms on Tuesday.

At this point, global models are depicting an increased likelihood of widespread convective activity Tuesday night, associated with a shortwave ejecting ahead of the main, more vigorous trough tracking across the lee of the Rockies. Although the precise track of this leading wave (whether across Iowa/Wisconsin or Illinois) remains uncertain, the favorable CAPE and shear environment should support elevated supercells and multicell clusters. The potential hazards include large hail, occasional downburst winds, and localized heavy rain.

The outlook for Wednesday hinges on the potential persistence of convective debris from the preceding night, with models diverging on its location. The GFS suggests this debris may linger over our area into Wednesday morning, preceding the main upper trough, while the ECMWF places it much further north, nearer to the surface front. Essentially, if we are cleared out to start Wednesday morning, there is a risk of severe weather and localized flash flooding by afternoon. Conversely, if convective debris enshrouds the area, these risks will be significantly reduced. Regardless of the Wednesday outcome, Thursday appears to offer a regionwide break, with synoptic- scale subsidence moving in behind the departing upper trough.

Thunderstorm activity returns by the weekend. The key concerns stem from persistent troughing over the western United States and a continuous northward flow of Gulf moisture up the Mississippi Valley, particularly by Friday night and Saturday. Such a pattern suggests that our area will continue to experience periods of convection. We will need to be vigilant of not only severe weather during this timeframe, but also of flooding as successive convective events compound.

Temperatures then cool significantly by Sunday as a cold front sweeps through the region, flushing out the resident warm and moist air mass from the week prior. Current NBM deterministic guidance supports afternoon highs near 60 degrees Sunday afternoon, with overnight lows near 40.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 520 AM CDT Sun Apr 12 2026

High-to-mid-level clouds are expected to cover the area through the afternoon. Scattered rain showers will develop from the west late in the afternoon but are anticipated to dissipate during the evening. Predominantly VFR conditions are forecast, although localized heavier showers could briefly reduce visibility to MVFR, hence the inclusion of a PROB30 group at all terminals. There is then a medium (40-60%) chance that broken MVFR ceilings trail the main push of rain through the remainder of the TAF period.

Winds will remain from the south today and increase,with gusts frequently reaching 30 knots.

ILX WATCHES/WARNINGS/ADVISORIES

None.