992 FXUS63 KILX 080755 AFDILX Area Forecast Discussion National Weather Service Lincoln IL 255 AM CDT Sun Aug 8 2021 .SYNOPSIS... Issued at 255 AM CDT Sun Aug 8 2021 A hot and humid weather pattern will dominate the region for the next several days. Periodic thunderstorm chances will persist from this afternoon through the first half of the week. Some of the storms this afternoon and evening could be strong to severe, and contain locally heavy rain. && .SHORT TERM...(Today and tonight) ISSUED AT 255 AM CDT Sun Aug 8 2021 MCS ongoing from central IA to northern MO aided by southwest LLJ and shortwave over the eastern Plains, is expected to diminish over the next few hours as it outruns better support. CAMs are in good agreement that convection will re-fire over southeast IA/northeast MO this afternoon as the trof pushes east. Downstream airmass across central IL will be moderately unstable with 2500 J/kg MLCAPE but marginal shear at 20-30 kt 0-6 km. This will favor a loosely organized cluster or linear structure to the storms as they track into western/central IL late afternoon and evening. Sporadic damaging wind gusts are the main threat with a weakening trend by mid evening east of I-55. Shower and storm chances continue overnight as a convergent 25-35 kt LLJ focuses on western IL. PWs rising to near 2" will bring a locally heavy rain and isolated flash flood threat with both the late afternoon and overnight storms, again mainly focused west of I-55. Hot and humid weather persists with highs in the upper 80s to lower 90s today and lows in the lower 70s tonight, with low 70s dewpoints common. Gusty winds up to 20-25 mph this afternoon in southwest gradient flow. && .LONG TERM...(Monday through Saturday) ISSUED AT 255 AM CDT Sun Aug 8 2021 Hot, humid, and unsettled weather remains on Monday when the shortwave trof axis pivots from IL into the lower Great Lakes. Given high instability, lingering boundaries could be the focus for another round of potentially severe storms and locally heavy rain. Behind this wave, heights rise on Tuesday which should lead to less storm organization, but with high instability and little to no cap in place by late afternoon will carry chance pops. Isolated heavy rain again a threat with slow storm motion and PWs near the top of climatology. Oppressive heat and humidity will likely be a bigger forecast concern Tuesday as mid to upper 70s dewpoints are likely. This combined with highs in the lower 90s will push peak heat indices toward advisory criteria of 105F. Another round of potentially intense convection is forecast by some guidance Tuesday night into Wednesday, when an upper jet shifts from the Plains into the Great Lakes. With the same airmass in place, at least a low end severe and heavy rain threat will exist. Heat indices may again be an issue, if organized convection does not materialize. Thursday into Thursday night, the longwave trof finally pushes into the upper Midwest, steering a cold front towards the region. The passage of this front will signal the end of the heat/humidity and active weather pattern. Progressively cooler and less humid air will filter in from the northwest for Friday and into the weekend as strong high pressure tracks from the upper Midwest to lower Great Lakes. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1150 PM CDT Sat Aug 7 2021 VFR conditions will prevail at all TAF sites next 24hrs unless storms are moving across the sites tomorrow late afternoon through evening. Cirrus will spread over the sites overnight and should become broken by mid tomorrow morning. Mid clouds around 15kft will advect into the area with broken cirrus, all from a decaying MCS that will be moving into the area. Any outflow boundary/front will become the focus for more convection tomorrow that will move across the sites late morning through evening. Question is when/where it will develop and when will it arrive at the sites. HiRes models differ slightly on timing but all show convection moving across the sites late afternoon into evening. Will start with VCTS and then have a 2-hr TEMPO group for when thinking best chance of storms on site. MVFR vis and cigs around 4kft will occur with the storms. Once this ends, could be some lingering precip/showers in the area, but did not add another line in TAFs to reflect that since there is still some uncertainty. Southerly winds will occur tonight around 8-10kts but then increase tomorrow out of the south through the day with gusts around 20-21kts in the morning, increasing to 22-25kts in the afternoon. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...25 SHORT TERM...25 LONG TERM...25 AVIATION...Auten