


Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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282 FXUS63 KILX 092307 AFDILX Area Forecast Discussion...Updated Aviation National Weather Service Lincoln IL 607 PM CDT Wed Jul 9 2025 .KEY MESSAGES... - After a brief lull in the precip chances today (<20%) there will be daily chances (20-50%) for showers and storms particularly during the afternoon and evening hours Thursday through the middle of next week. - Temperatures will generally be seasonable (highs in the mid 80s) the rest of the week and weekend with Friday being the warmest day with highs around 90F. && .DISCUSSION... Issued at 144 PM CDT Wed Jul 9 2025 Weak surface ridging is in place across central Illinois this afternoon which is resulting in generally fair weather across the region. While an afternoon or evening isolated pop-up shower or storm cannot be completely ruled out today, most of the area will be dry through tonight. By Thursday, surface ridge axis will inch east into Indiana with a bit of a mixed picture on convective chances through the day. Dew points will creep back up into the lower 70s for much of the area contributing to moderate instability across the region. GFS advertises around 1500 J/kg MLCAPE which will be weakly capped (generally less than 30 J/kg MLCIN). Despite the atmosphere primed for thunderstorms, synoptic scale forcing will be well west of the area with eastern portions of Illinois still under the influence of the surface ridge. Still, some of the CAMs suggest a convectively induced vort max will move into portions of central Illinois Thursday late afternoon/evening and could serve as the focus for some scattered storm development. Should this occur, a few stronger storms will be possible with damaging downburst winds and locally heavy rain due to slow storm motions the primary concerns. Week flow aloft and weak deep layer shear will keep the threat for a more organized severe threat low. On Friday, a more robust trough is progged to move east along the Canada/US border while a southern stream wave lifts from the central Great Plains into the Upper Midwest. A deepening surface low over the Upper Midwest will lift a warm front across central Illinois through the day. Temperatures will warm to around 90 degrees within a broad warm sector while dew points further climb into the mid 70s. Strong instability will result with MLCAPE values exceeding 3000 J/kg expected by Friday afternoon and evening. Mid level warm air advection could drive some showers and storms during the day Friday, but the main concern will be Friday evening as storms grow upscale over the mid Missouri Valley in response to a developing low level jet. These storms will congeal into a line and move east along the instability gradient into portions of Illinois late in the evening and overnight. While there will be a gradually diminishing severe threat with time through the overnight hours, it`s possible that some of these storms could reach and maintain severe levels as they push into the state. Uncertainty in some of the placement/timing details remains which keeps the SPC D3 marginal risk right on our doorstep for the time being. Depending on the evolution of storms Friday night and placement of remnant outflow boundaries Saturday (impacting the location of the effective cold front), there will be some potential for additional strong to severe storms over the weekend. Areas further north in the state will be less warm with highs back in the lower to mid 80s, but closer to the effective front across the southern half of the state temps will continue to run warmer with highs near 90F. Deubelbeiss && .AVIATION... (For the 00z TAFs through 00z Thursday Evening) Issued at 607 PM CDT Wed Jul 9 2025 A ridge of high pressure across the central IL terminals should bring an early end to isolated -SHRA by around 01Z-02Z this evening, then enough clearing and light winds that areas of fog could form late tonight. As a general theme, model guidance develops fog first over east-central to northeast IL around 08Z, then expand it southwestward through much of central IL by sunrise. Have therefore included MVFR vsbys by 09Z-10Z, with a tempo for IFR 10-12Z, then anticipate fog lifting by 13Z. There is a chance for isolated to scattered thunderstorms developing after 20Z-22Z Thursday, and have included PROB30 for TSRA. Winds WNW 4-8 kts this evening, becoming light and variable overnight, then returning from the SW after 13Z at around 4-8 kts. 37 && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$