textproduct: Central Illinois

KEY MESSAGES

- Periodic shower and storm chances will continue through at least the middle of next week. Showers and possibly (20% chance) a thunderstorm near the I-74 corridor this afternoon may generate localized small hail and wind gusts over 40mph.

DISCUSSION

Issued at 201 AM CDT Thu May 7 2026

***** FEW GUSTY SHOWERS THIS AFTERNOON, RAIN TOMORROW *****

Tranquil conditions are observed across central and southeast Illinois early Thursday morning, as surface high pressure is favoring light and variable winds. A band of mid level clouds in west-central Illinois at 2am is slated to shift east across the county warning area (CWA) through daybreak, but given the short (2-4 hour) duration these are overhead in any given location we suspect temperatures will drop into the mid 30s for spotty frost by dawn.

A weak mid level disturbance will spark a few showers across portions of central Illinois this afternoon and evening, mainly north of a Rushville Paris line. With enough sunshine ahead of these showers late morning into early afternoon, deep mixing should favor an inverted V up to 750-800mb and even 75-150 hundred J/kg SBCAPE through the hail growth zone. This suggests the stronger cells may produce thunder, small hail, and gusty winds over 40 mph, though lack of deep moisture suggests a low (less than 5%) risk for severe weather.

Yet another disturbance, fast on the heels of this one, will bring more numerous showers to the area tomorrow morning into early afternoon. High Resolution Ensemble Forecast (HREF) mean rainfall from this system is generally between 0.25 and 0.5 inches, but individual convective allowing models (CAMs) and the localized probability matched mean (LPMM) suggest a few pockets of over an inch may occur. If the NAM/RAP/GFS are right in depicting 40-55 kt deep layer shear and a couple hundred J/kg MUCAPE, we may also have a few rumbles of thunder during the afternoon, but once again the severe weather risk appears low (less than 5%).

***** MORE SHOWERS SATURDAY NIGHT INTO SUNDAY MORNING *****

The next shortwave trough is forecast to arrive Saturday night. Ahead of it, a stronger push of warm air advection (WAA) will warm 850mb temperatures into the 10-12 degC range if you believe the Low Resolution Ensemble Forecast (LREF) mean. This will bring Saturday afternoon high temperatures solidly into the 70s, with a 40-75% chance (highest west) for 75+ degF from the National Blend of Models (NBM). This system will also bring another round of showers and possibly (20% chance) a few thunderstorms to the area Saturday night into Sunday morning. In fact, NBM gives a 25-40% chance (highest south) for more than a half inch of additional rainfall to the district by noon Sunday.

The pattern remains active next week, as the Prairie State remains sandwiched between a ridge of high pressure across the Great Plains and an upper level low pressure system spinning over eastern Canada. Global models disagree on timing and placement, but virtually all of them have one or more shortwave disturbances sparking showers and storms either over our area or nearby next work week.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1244 AM CDT Thu May 7 2026

VFR conditions will prevail at all TAF sites next 24hrs. High cirrus will advect and be over the sites now until morning. Then scattered clouds and mid clouds will move in ahead of the boundary and associated showers. This will affect PIA, BMI, and CMI only. SPI and DEC will remain dry with mid and high clouds through the period. Precip will start as VCSH with a prob30 for more showers and slightly lower cigs...around 7kft. Believe predominate showers will occur in the afternoon at PIA and BMI, but not CMI. After the predominate showers, will have another prob30 for PIA and BMI and just VCSH for CMI. Winds will be light then become southwest ahead of the system, followed by west to southwest winds this afternoon and evening. Speeds will increase to gusty at 23-25kts for the afternoon, then become lighter and south-southwest this evening.

ILX WATCHES/WARNINGS/ADVISORIES

None.