965 FXUS63 KDVN 310531 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 1231 AM CDT Sat May 31 2025 .KEY MESSAGES... - Smoke from Canadian wildfires will continue to flow southward through the weekend, with some of the smoke mixing down to the surface, leading to reduced air quality at times - Active pattern returns next week, bringing higher chances for widespread showers and storms && .SHORT TERM /THROUGH SUNDAY/... Issued at 216 PM CDT Fri May 30 2025 We continue to see a deep longwave upper-level trough over the northeastern CONUS this afternoon, placing our region at the apex of northerly flow streaming southward from Canada. Embedded within this flow is a mid-level shortwave that will continue to dive southward this afternoon and evening, but the bulk of the forcing should be focused east of our region, closer to Lake Michigan. If any locations in our CWA see any showers, it will likely be just Stephenson county, with the rest of the area remaining dry. Latest GOES-East Geocolor satellite imagery continues to show a pronounced plume of smoke from Canadian wildfires continuing to surge southward over the Corn Belt. Latest HRRR Smoke model cross sections indicates smoke aloft progged around the 850-700 mb layer, and with deep boundary layer mixing this afternoon reaching to this layer with an inverted-V signature, at least some small degree of the smoke should mix down to the surface. There is some discrepancies between the HRRR and RAP smoke models on the exact concentration of the smoke at the surface, with the HRRR quite a bit more aggressive than the RAP. We will continue to maintain patchy smoke in the forecast. With northerly flow aloft expected throughout the weekend, we should continue to see smoke aloft, perhaps mixing down to the surface at times. For Saturday, a backdoor cold front is expected to move to the southwest across the region, which could spark some showers and storms in the afternoon hours. Confidence in this activity is a bit lower, owing to a mixed bag of solutions from the CAM guidance as some have a line of showers and storms forming along the boundary, while others keep things dry. Due to this lower confidence, we have maintained slight chances PoPs (<20%). If showers/storms do form, they will likely be over southeastern Iowa into west-central IL and far northeast MO. MLCAPE of 500-1000 J/kg will be possible to fuel any storms, but deep-layer shear looks to be pretty modest (up to 30 kts at best). Thermal ridging to the west of the CWA should lead to warming temperatures from the west, with highs Saturday in the middle 70s over northwest IL to the middle 80s to the southwest. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Issued at 216 PM CDT Fri May 30 2025 By Saturday night, any lingering showers and storms from the afternoon (if any form at all!) should come to an end by the evening as the backdoor cold front exits the region and surface high pressure strengthens over the western Great Lakes region. For Sunday and Monday, mid-level ridging over the central to northern Plains region should keep conditions dry and quiet in our region. The main story for this time frame will be a noticeable warm-up as 850 mb temperatures per the EC and GEFS ensembles increase to between 15-18 degrees C, which is around the 90th percentile per the SPC sounding climatology. The ECMWF EFI for high temperatures on Monday is also indicating values between 0.7 to 0.9 for some locations, which suggests an anomalously warm day. The latest NBM suggests high temperatures warming to the lower to middle 80s across the area Sunday, with perhaps some upper 80s to even lower 90s for Monday. For Tuesday through Thursday, a more active pattern is expected as an upper-level trough approaches the region, along with an attendant cold front. Abundant moisture from the Gulf should advect northward, which will support Pwat values around 1.6 to 1.9 inches per the GEFS ensemble plumes. This first trough should be followed up by a southern stream trough coming from the southwestern CONUS, arriving on Thursday. Combined, these two rounds of showers and storms should result in at least a soaking rainfall over the area, with NBM exceedance probabilities of a half inch or more of total rainfall between 60 to 80 percent and between 40 to 60 percent for an inch or more. In terms of severe potential, uncertainty remains on the extent of the storms and timing of the troughs, but GEFS ML severe probs still indicate a low-end chance of stronger storms, so this potential will need to be watched. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1225 AM CDT Sat May 31 2025 VFR expected overnight into Saturday with steady WNW to N winds. Low chance for an isolated shower or thunderstorm to develop during the late afternoon and evening, mainly southwest/south of Dubuque. However, did not mention in TAFs due to expectation for very low areal coverage and low chance on direct impacts at the terminals. Wildfire smoke aloft will remain over the area through the period and could potentially mix down to the surface at times in low concentrations. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...Schultz LONG TERM...Schultz AVIATION...Uttech