FXUS63 KDVN 181728 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 1228 PM CDT Mon May 18 2026 .KEY MESSAGES... - Another round of storms tonight, with the chance for some of them to be strong to severe. - Turning cooler and breezy Tuesday behind a cold front, with dry conditions expected to then last through at least Thursday. && .SHORT TERM /THROUGH TONIGHT/... Issued at 315 AM CDT Mon May 18 2026 Will walk out ongoing linear MCS that has become mainly outflow dominant, although a few isolated strong wind gusts may still occur. Also some isolated precursor WAA cells have developed ahead of the main line and with an elevated nature may produce some hail. Such a weakening larger system and inherent pressure perturbations may produce more trouble with wake low winds gushing out of the system's backside, possibly of 45 to 55+ MPH. Some of the CAMs even suggested this by mid morning south of I-80 acrs west central IL and far southeast IA. Areas of post-convective line stratiform rain with embedded thunder to be the last to clear as the morning progresses. Then again it's the same scenario of how much the convective debris can clear to allow for some heating, and also aided by breezy south to southwest sfc winds again this afternoon. Will go with 50 percentile widespread low 80s for highs today with sfc DPTs remaining in the 60s. The local area should remain dry while the current system lights up renewed convection to the south acrs central MO into central IL. Tonight...may be a similar scenario as to what has and is occurring this Sunday night/Monday morning. The main upper trof will dig out acrs the east central plains with mid and upper jet support, and the main sfc front located along the MO RVR Valley. MCS generation tools all come together to suggest rapid and strong convection to fire late this afternoon from central KS and up the MO RVR Valley. Storm propagation vectors and CAPE "hunger" has this activity growing upscale and feeding east with aid of 40-50 KT SSW LLJ flow as another squall line moves east acrs IA and northern MO. There may be more support and a probable earlier start to allow some of this activity to still be strong to severe with damaging straight line winds(as opposed to this Monday AM) as the linear MCS arrives. 0-3KM shear vectors and LLVL THTA-E lapse rates may also support some meso- vortice type spin up tornadoes along any LEWP or comma head updraft- downdraft balance regions. Locally heavy rain with the passing storm lines with high rates, but again progressive nature of the system should preclude much of a widespread flash flood threat. Would expect a weakening trend with the convection as it propagates eastward acrs the rest of the DVN CWA into the late night hours and into early Tuesday morning as storm outflow outraces the main line again. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Issued at 315 AM CDT Mon May 18 2026 Tuesday...Morning convective debris and possibly a few post-frontal isolated light showers to eventually clear off for a blustery and cooler day. A large temp range acrs the CWA from west-to-east, with the east experiencing 12 hour high temps in the morning along and just post-frontal and then falling off into the 60s. The rest of the week looks below normal under high pressure until moderation occurs into the start of the weekend. Also mainly dry until an upstream upper trof tries to battle it's way eastward into the ridge complex with some moisture draw for increasing precip chances by Friday. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 1228 PM CDT Mon May 18 2026 Some MVFR to VFR conditions lingering today behind earlier convection, with an expectation MVFR to low VFR deck to develop ahead of the next round of precipitation to move into late this evening/tonight. Winds have been some variable with weak influences lingering from last night's storms, but a boundary in place from southwest to northeast across Iowa to the northwest of the area that should allow for southerly flow to southwesterly flow to setup by this evening with that boundary to move through behind the storm's late tonight with winds to shift around to the west to northwest for Tuesday. Expect a band of showers/storms to spread across the area from the west/southwest late this evening into the overnight hours, with low IFR to MVFR CIGS developing behind the precipitation and boundary moving through the region into Tuesday morning. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...Hladik LONG TERM...Hladik AVIATION...MJB