164 FXUS63 KILX 131954 AFDILX Area Forecast Discussion National Weather Service Lincoln IL 254 PM CDT Mon Sep 13 2021 .SYNOPSIS... Issued at 251 PM CDT Mon Sep 13 2021 Hot and humid conditions will continue into the day Tuesday ahead of an approaching cold front. Scattered showers and storms are expected across portions of central Illinois Tuesday afternoon and evening as the front moves across the region. Precipitation chances linger into the day Wednesday, then expect dry conditions through the remainder of the week. && .SHORT TERM...(This evening through Tuesday) ISSUED AT 251 PM CDT Mon Sep 13 2021 This afternoon, a warm front is draped roughly along the IL/WI state line with thunderstorm chances mainly north of the front this evening and tonight. Across central Illinois, fair weather will persist with a modest south breeze expected through the night helping to prop up temps with overnight lows in the lower to mid 70s. Low pressure over the central Great Plains this afternoon will track across the Great Lakes Tuesday pushing a trailing cold front across central Illinois. Ahead of the front, temperatures warming into the upper 80s with dew points in the lower to mid 70s will contribute to moderate diurnal instability with MLCAPE values increasing to around 1500-2000 J/kg. Meanwhile, deep layer shear will be marginal, but increases through the day to around 25-30 kt in the vicinity of the front during the afternoon. Guidance is in reasonably good agreement that thunderstorms will initialize along the front mid afternoon between the Illinois River Valley and the I-57 corridor. Steep 0-3 km lapse rates of 7.5-8.5 C/km will support efficient mixing down of winds and support a damaging wind threat with stronger storms. If shear is able to be strong enough to support a few supercells, an isolated hail/tornado threat will also be present. && .LONG TERM...(Tuesday night through Monday) ISSUED AT 251 PM CDT Mon Sep 13 2021 By Wednesday morning, the slow moving front is expected to stall near or just south of the I-70 corridor. A broad 500mb trough will move across the region Wednesday providing additional chances for showers and storms in the vicinity of the front, mainly south of the I-72 corridor. Guidance suggests modest instability up to around 1000 J/kg MLCAPE will be in place near the front Wednesday afternoon, but deep layer shear will be diminishing through the day as the upper jet pulls away across the Great Lakes. 0-6km shear values of 15-25 kt during the afternoon hours will be a limiting factor in terms of any organized severe threat Wednesday. After a brief moderation of temperatures Wednesday with passage of the cold front, upper ridge builds back across the region while the h85 thermal ridge builds just to our west and northwest through the weekend. Veering low level flow and building heights will push afternoon highs back into the mid to upper 80s Friday though Monday. While couldn't completely rule out some isolated diurnal thunderstorm development, most of this time frame will be dry. && .AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon) Issued at 1240 PM CDT Mon Sep 13 2021 Breezy south to southwest winds will be in place through the period along with VFR conditions. Winds will veer to SW/WSW ahead of an approaching cold front later in the morning and into the afternoon Tuesday. Precip chances along the front will be beyond the current TAF valid period. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...Deubelbeiss SHORT TERM...Deubelbeiss LONG TERM...Deubelbeiss AVIATION...Deubelbeiss