textproduct: Central Illinois

KEY MESSAGES

- A Flood Watch continues for locations along and south of Shelby, Moultrie, Douglas and Edgar counties until 1 pm Saturday afternoon. The Flood Watch has been canceled for Scott, Morgan, Sangamon, Macon and Christian counties. Up to an additional inch of rain is expected through this evening over the Flood Watch area, with locally higher amounts in southeast IL.

- The first prolonged heatwave of the summer will arrive next week, when air temperatures rise into the low to mid 90s and maximum heat index values climb into the upper 90s and lower 100s Sunday afternoon and 100 to 110 degrees Monday through Friday during the afternoon and early evening hours.

DISCUSSION

Issued at 240 PM CDT Fri Jun 26 2026

*** Locally Heavy Rainfall and Flood Watch Southeast IL ***

A Flood Watch has been canceled for Scott, Morgan, Sangamon, Macon and Christian counties and continued until 1 pm Saturday from Shelby, Moultrie, Douglas and Edgar counties south. Storm total rainfall since Thursday afternoon has been generally a quarter to half inch over central IL with some spots only getting up to a tenth inch. Southeast IL has generally had half to 1.5 inches with local 1.5-3 inch amounts amounts south of I-70. Showers have become more widespread and heavier in spots over central IL past few hours while A few bands of heavier rains were south of I-70 with isolated thunderstorms and tracking ENE. A quasi-stationary frontal boundary was south of I-72 along a Taylorville to just south of Paris line and extended through central MO to 1005 mb low pressure in north Texas panhandle. PW values range from 1.7-2.1 inches over CWA with highest amounts in sw CWA and have been slowly increasing during today. Latest CAMs bring weak surface low pressure ENE into central IL late tonight and into central IN by late Sat afternoon. Widespread showers this afternoon and early evening to gradually diminish from the west during the evening. SPC day1 outlook has marginal risk of severe storms over Clay, Richland and Lawrence counties into mid evening for 5% risk of damaging wind and 2% risk of tornadoes. Up to an additional 1 inch of rain possible in southeast IL with locally higher amounts possible into this evening. More of the Flood Watch may be cancelled during tonight as convection chances wane. Could see some patchy fog and drizzle with low clouds overnight into mid Saturday morning. Otherwise convection chances are more widely scattered on Saturday with best chances in eastern IL Sat afternoon. A warm front lifting ne Saturday night to renew chances of convection by late Sat evening and overnight. SPC Day2 outlook has marginal risk of severe storms for 5% risk of damaging winds and large hail along and sw of a Canton to Lincoln to Terre Haute line.

*** Heat Wave Expected Next Week ***

As warm front lifts northeast of central IL during Sunday could see isolated convection. But main weather story will be the increase heat and humidity starting Sunday afternoon as strong upper level high pressure ridge settles over the mid MS river valley by late Sunday and ridging over IL much of the upcoming work week. Highs Sunday in the upper 80s and lower 90s with dewpoints climbing into the 70s, giving afternoon heat indices of 96-104F Sunday afternoon, highest from Macomb to Springfield to Lawrenceville sw. Even hotter and more humid conditions expected Monday and to persist much of next week. Highs in the low to mid 90s Monday through Friday with lows and dewpoints in the 70s and afternoon heat indices of 100-110F Monday through Friday. We will likely need heat headlines much of next week over central and southeast IL as this will be our strongest and longest heat wave so far this year. Convection chances are less than 20% Monday thru Thu morning. Then 20-30% chance of convection Thu afternoon into Friday night as some disturbances pivot north and ne on western edge of strong upper level high pressure ridge over the Ohio/TN river valley.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1218 PM CDT Fri Jun 26 2026

Weak low pressure riding along a stalled-out surface front will keep substantial aviation impacts intact across the central Illinois terminals, as low clouds and periods of rain support poor ceilings and visibility throughout this TAF cycle.

While MVFR and occasional IFR ceilings will be in place through the remainder of this afternoon and evening, short term model guidance suggests a high (60-90%) probability of IFR ceilings developing and persisting through the overnight hours, occasionally becoming LIFR.

Poor flight conditions will linger through much of the morning hours on Saturday as drizzle and patchy fog persist in the vicinity of the slow-moving surface front.

Surface winds will maintain a light east to northeast component throughout this TAF cycle.

ILX WATCHES/WARNINGS/ADVISORIES

Flood Watch through Saturday afternoon for ILZ054>057-061>063- 066>068-071>073.