FXUS63 KDVN 190544 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 1244 AM CDT Tue Aug 19 2025 .KEY MESSAGES... - Thunderstorms, some strong to severe early this evening in NW IL. Localized torrential rainfall leading to flash flooding is also possible. - Mostly dry and more seasonal conditions are expected from later Tuesday and especially Wednesday through the upcoming weekend. && .SHORT TERM /THROUGH WEDNESDAY/... Issued at 210 PM CDT Mon Aug 18 2025 Tonight...In watching for the latest storm development this afternoon and evening, the prime axis appear along a 3000+ J/kg MLCAPE area from the STL area up through the central WI/IL border, including the far eastern portion of the DVN CWA. A secondary area may be along a MLCAPE gradient in the vicinity of a MCV from east of DSM and acrs the northern 1/2 or so of the DVN CWA. This secondary area along and north of I-80 is where several of the latest CAMs light up convection over the next few hours. Will have to have POPs to cover both areas and scenarios. With the high CAPEs and low LCL's, damaging wind gusts and a tornado are the prime concerns. Near two inch PWAT's in place support localized torrential rainfall at high rates again, and thus a slow moving storm may be able to flood. But effective shear is marginal at 20-30 KTs, and deeper layer lapse rates are weak, so some things against a higher severe threat. After mid evening, expect the convective activity to wane and slip east/south into the overnight hours along with the migration of the main frontal system. Light north winds should be CWA-wide by dawn. But there are some signs of at least patchy fog development in the north around dawn as well, but it may be more widespread toward the MN/IA border region. Low temps in the lower 70s to upper 60s. Tuesday...A day with increasing post-frontal influence and deepening northerly fetch acrs the area. A low chance for an isolated shower or storm in the heating of the day, but there may be a large field of post-frontal clouds putting the clamps down on instability build up and a high temp potential buster. A secondary short wave dropping down in steepening northwesterlies may try to kick up isolated showers acrs MN and WI Tue evening, with a low chance for some of that activity try try and make it down into our north. Otherwise clearing and continued with the cool advection for widespread low temps down in the mid to upper 60s. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Issued at 210 PM CDT Mon Aug 18 2025 Largely dry conditions are expected for Wednesday through the upcoming weekend, with perhaps our next chances of precipitation coming Friday night as another front approaches the region. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1232 AM CDT Tue Aug 19 2025 Expansive deck of LIFR/IFR stratus across WI to drift south into portions of eastern IA and northwest IL this morning. In addition, a very moist boundary layer and winds under 4kts will allow for fog formation prior to sunrise. Some of this fog may become dense, with highest probabilities (60-70%) occurring after 11z at DBQ. Have left out of other TAF sites for now, but will monitor trends upstream and amend if necessary. Model guidance is mixed as to when conditions improve to VFR today, but should start to scatter out by late morning and early afternoon. Northerly winds under 10kts will be seen through the period. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...12 LONG TERM...Schultz AVIATION...Gross