


Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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255 FXUS63 KILX 090858 AFDILX Area Forecast Discussion National Weather Service Lincoln IL 358 AM CDT Wed Jul 9 2025 .KEY MESSAGES... - There will be daily chances (20-50% coverage) for showers and storms over central and southeast through the remainder of the week and into the weekend. Thunderstorms will generally be favored during the afternoon and evening hours, except for Friday night as a warm front lifts northward across the area. - Seasonable heat and humidity will remain in place the remainder of the week into this weekend with afternoon highs generally in the mid to upper 80s and dew points in the 70s. Friday will be the hottest day this week with highs around 90 and afternoon heat indices peaking in the upper 90s to around 100 degrees. && .DISCUSSION... Issued at 355 AM CDT Wed Jul 9 2025 The predawn surface map shows a frontal boundary draped north of IL from central lower MI into southeast WI and central Iowa. Radar mosaic shows scattered showers over eastern parts of Vermilion and Edgar counties eastward into west central Indiana, with very isolated light showers in southeast IL. Areas of fog had developed past few hours over the IL river valley, west of I-55 where low and mid level clouds had decreased. Though even in the cloudier areas east of I-55 we are getting some fog with stratus clouds like at Taylorville with 1/2 mile vsby and 200 foot ceiling. Have increase coverage of fog over nw half of CWA into early morning and will see pockets of dense fog too. We will monitor possibility of dense fog advisory over parts of IL river valley if fog get more dense and widespread next few hours. Fog should lift by mid morning while more clouds prevail in east central and southeast IL today. Isolated to scattered convection to develop this afternoon with unstable airmass with MLCapes of 1400-1800 J/kg over southern/eastern CWA but very weak wind shear values around 10 kts. So a few pulsey type storms possible this afternoon with gusty winds and locally heavy rains. SPC Day1 does not have a marginal risk over our area today and WPC Day1 ERO has marginal risk of excessive rainfall over far se IL. Highs today in the mid to upper 80s with heat indices peaking in the lower 90s this afternoon. Isolated convection early this evening otherwise much of tonight dry. Could see patchy fog develop overnight over ne and eastern CWA with light winds and moist boundary layer. Lows overnight in the mid to upper 60s. Isolated to scattered convection to develop during Thu afternoon as airmass gets more unstable again especially sw half of CWA as MLCapes rise back to 1400-1800 J/kg and wind shear values a bit higher than today at 15-20 kts. SPC Day2 does not have marginal risk of severe over CWA on Thu afternoon/evening (marginal risk is over Iowa) but could be a few stronger cells with gusty winds sw and west central CWA Thu afternoon and early Thu evening. Highs Thu in the mid to upper 80s and afternoon heat indices in the lower 90s so similar to todays readings. A stronger short wave trof moving over the Midwest on Friday to have higher chances of convection nw of CWA Fri afternoon with our pops of 30-40% Fri afternoon, and mainly slight chance in southeast IL. Gets more unstable Fri afternoon with MLCAPES 2-3k J/kg (highest sw CWA) wind wind shear increasing as well to 25-30 kts by late day. Could be a few stronger storms especially nw CWA Fri afternoon/evening with low level jet placing a role Friday night. Warm front lifting northward Fri afternoon and Fri night to bring hot and humid conditions with highs around 90F and afternoon heat indices in the upper 90s to around 100 degrees on Friday. Good chance of convection Friday night and Saturday especially during the afternoon hours. More unstable airmass is over southeast IL Sat afternoon with MLCAPes around 2500 j/kg so could be some strong to severe storms Sat afternoon in southeast IL. Models have trended wetter over CWA by Sunday afternoon as a system approaches from the Central Plains. Heat and more tropical humidity looks to return early next work week as upper level ridge builds more into IL as 500 mb heights rise to near or above 591 dm. 07 && .AVIATION... (For the 06z TAFs through 06z Wednesday Night) Issued at 1210 AM CDT Wed Jul 9 2025 Main aviation concerns will be in the first 6-8 hours of the forecast. An area of clearing along the Illinois River is showing signs of developing low stratus and dense fog, with the 05Z observation at KPIA coming in at 1/4SM. The extent of the stratus and fog will depend on how far east the clearing makes it, which may not make it much further than KBMI/KSPI as the stratus takes over. Will keep the IFR/LIFR conditions confined to these three sites, though ceilings below 2000 feet will make it further east with time. Ensemble probabilities show significant improvement in the 14-15Z time frame, with any lingering ceilings after that mainly around 4-5kft. Geelhart && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$