FXUS63 KDVN 261959 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 259 PM CDT Fri Apr 26 2024 .KEY MESSAGES... - Active pattern through the weekend with rounds of showers and thunderstorms with an additional 1-3+ inches of rain likely. - Flash Flooding is a concern for areas that receive repeated rounds of thunderstorms Saturday night. Confidence remains low on the placement of the heaviest rainfall. - Severe storm risk exists through the weekend, but there remains uncertainty as prior rounds of convection may impact magnitude/timing/location of any severe weather threat. && .SHORT TERM /THROUGH TONIGHT/... Issued at 255 PM CDT Fri Apr 26 2024 A large area of light to moderate rain will continue to work through the region from SW to NE into the late afternoon hours. There have been embedded thunderstorms at times mainly along/south of I-80, but this heavier activity has diminished significantly over the past few hours. On the northern edge of the rain shield, across portions of eastern Iowa into northwest Illinois, we had a period of strong SE winds during the mid to late morning with many locations peaking between 40 - 50 mph. Cedar Rapids was the outlier, reaching 65 mph! These unexpected strong winds occurred in a region of subsidence sufficient to mix down momentum tied to a robust southeasterly LLJ. Still gusty SE to S winds will continue through this evening into tonight, but likely on the order of 30 to 40 mph for peak gusts. Persistent elevated warm air advection north of a warm front draped across northern Missouri will likely lead to another round of scattered showers and isolated storms developing this evening into early tonight. However, coverage with this round does not look to be quite as widespread as earlier today. Any threat for severe weather remains low as the better moisture is forecast to hold south across central Missouri and the stronger dynamics to the west near a surface low over western/central Iowa. By late tonight, expect mostly dry conditions with breezy S to SSW winds. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Issued at 255 PM CDT Fri Apr 26 2024 Saturday: A lull in convection is anticipated through much of the day as low pressure shifts toward Lake Superior with the attendant cold front/low-level boundary expected to hold to our west across central Iowa. Gusty southerly winds developing tonight (Friday night) will last through the day on Saturday and advect a warm and humid air mass into the region with highs in the upper 70s to low 80s; dewpoints rising into the 60s will make it feel rather humid. There is a low chance for isolated storms during the early/mid afternoon period; however, confidence is low on activity developing that early. The better chance for storms is Saturday evening into the nighttime as a mid-level wave approaches from the southwest. Confidence remains low on the exact placement for this period, but the environment will be supportive of strong to severe storms with sufficient MUCAPE (2000+ J/kg) and deep layer shear (35+ kts). The primary threat into Saturday night may transition to heavy rainfall and localized flash flooding with high PWATs up to 1.5 inches. There is also the potential for repeated rounds of storms as mean 850-300mb flow steers the convection in a SW to NE trajectory, as a new area of low pressure organizes over the Central Plains. The 12Z HREF that grouped several of the CAMs output together shows localized amounts over 3 inches in our CWA. A Flood Watch may be needed eventually due to the potential for an additional 1-3+ inches of rainfall through the weekend. Held off for now because of the aforementioned low confidence on placement of the heaviest rainfall. A look at the latest 1 - 3 hr flash flood guidance shows values approximately in the 1.5 to 3 inch range. Sunday: The upper low will lift out and take a similar path to the previous shortwave from Colorado into the Upper Midwest by Monday morning. We'll see widespread showers and storms occur Sunday into Sunday night with the warm, moist advection and increasing synoptic scale lift then followed by the cold frontal passage Sunday night into Monday AM. The widespread precipitation and cloud cover brings about uncertainty as to the severe weather potential and magnitude/location, etc. Overall, we have 2 surges of PWATs of around 1.5 inches the first today into this evening and the second Saturday night through Sunday. Those would be the periods favored for locally heavy rainfall concerns. Between both events many areas will see widespread 1 inch or more (today through Sunday) with areas/swaths of 2 - 4+ inches where rounds of convection occur that will bring a risk of isolated flash flooding. In the wake of the cold front, the start of next week looks to turn quieter and drier. However, there's signs that an active pattern will return mid to late next week with the flow becoming semi-zonal shuttling impulses across the Midwest from the Pacific along a meandering mid level baroclinic zone. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1227 PM CDT Fri Apr 26 2024 Active weather today into tonight will lead to poor aviation conditions with periods of showers and storms, accompanied by MVFR/IFR ceilings and visibilities. The best chances for occasional embedded thunder are at MLI and BRL, with lower instability anticipated further to the north. Another round of scattered showers and isolated storms is forecast to develop this evening into early tonight and shift SW to NE through the region. Additionally, gusty SE to SSW winds will continue through tonight. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...Uttech LONG TERM...McClure/Uttech AVIATION...Uttech