FXUS63 KILX 191819 AFDILX Area Forecast Discussion...Updated Aviation National Weather Service Lincoln IL 119 PM CDT Tue Aug 19 2025 .KEY MESSAGES... - There is a low probability (20-30% chance) for thunderstorms along and south of I-70 through early this evening. - The recent intense heat has come to an end...as readings drop back to near normal in the middle to upper 80s for the remainder of the week. - A second cold front may trigger an isolated shower on Saturday, followed by even cooler highs in the 70s by early next week. && .DISCUSSION... Issued at 1253 AM CDT Tue Aug 19 2025 18z/1pm surface analysis shows a cold front approaching the I-70 corridor. The airmass ahead of the front remains oppressively hot and humid with heat index values above 100 degrees. Meanwhile to the north, winds have veered to the N/NW and air temps have fallen into the lower to middle 80s. A band of enhanced Cu currently accompanies the boundary, and this will be the area to watch for widely scattered convection this afternoon. CAMs have consistently focused the greatest areal coverage of showers/storms further upstream across Indiana...and this seems reasonable given latest satellite/radar trends. As a result, am carrying just 20-30 PoPs along/south of a Paris to Taylorville line over the next couple of hours, then lingering south of I-70 until about 02z/9pm. Skies will partially clear and winds will decrease to 5mph or less tonight. With ample boundary layer moisture still in place as shown by surface dewpoints hovering in the middle to upper 60s, the stage will be set for patchy fog development...particularly where recent rainfall has been the heaviest. The models (other than the GFSLAMP) are not advertising much fog: however, think they are underdoing it and have thus added patchy fog to the forecast along/north of the I-72 corridor toward dawn Wednesday. Skies will initially be mostly sunny Wednesday morning: however, the NAM Cu-rule becomes strongly negative as a trough axis currently upstream across Minnesota/South Dakota drops southward into Illinois. Based on forecast soundings, skies will become partly to mostly cloudy for a time from late Wednesday morning into the afternoon...and isolated showers cannot be ruled out by peak heating. Several CAMs suggest a few showers during the afternoon, especially along/west of the I-55 corridor. Areal coverage will be minimal and any rainfall that occurs will be light. Once the trough drops south of the region and high pressure builds in from the north, dry and seasonably warm readings in the middle 80s are anticipated for Thursday and Friday. Further out, models are in excellent agreement that a vigorous short-wave trough evident on current water vapor imagery off the coast of British Columbia will track eastward over the next couple of days, then dig into the Great Lakes over the weekend. This will push a re-enforcing cold front into central Illinois on Saturday. While recent runs of the NBM have been dry, several models are at least hinting at widely scattered showers/thunder along the front. Given favorable timing during peak heating, think a low probability (20% chance) for convection is warranted with FROPA Saturday afternoon. Once the front passes, an even cooler/less humid airmass will arrive by early next week...with highs dropping into the 70s Sunday through Tuesday. Barnes && .AVIATION... (For the 18z TAFs through 18z Wednesday Afternoon) Issued at 119 PM CDT Tue Aug 19 2025 A cold front has pushed south of the terminals leaving a modest northerly breeze in its wake. MVFR ceilings are in place near and north of the I-74 corridor early this afternoon, but are expected to lift/scatter to VFR over the next few hours. MVFR ceilings may redevelop as diurnal cumulus develops mid to late Wednesday morning, especially along the I-74 corridor. Deubelbeiss && .ILX WATCHES/WARNINGS/ADVISORIES... Heat Advisory until 7 PM CDT this evening for ILZ066>068-071>073. && $$