584 FXUS63 KDVN 012337 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 637 PM CDT Sun Jun 1 2025 .KEY MESSAGES... - Smoke aloft from Canadian wildfires will continue to stream southward over our region through Monday. Some of the smoke could mix down to the surface and lead to reduced air quality at times, especially Monday afternoon. - An active pattern returns Tuesday through Thursday, bringing high chances (70-90%) for widespread showers and storms. Some storms could become strong to severe Tuesday, although uncertainty remains on the details and overall potential. - Largely beneficial rainfall is expected later this week, with most of it falling Tuesday and Tuesday night. Flooding threat should remain minimal, except if copious rainfall occurs over urban areas. && .SHORT TERM /THROUGH MONDAY NIGHT/... Issued at 207 PM CDT Sun Jun 1 2025 High pressure over the western Great Lakes will continue to dominate over the region for the rest of today, keeping conditions dry under hazy sunshine. Current geocolor satellite imagery continues to show an expansive area of smoke aloft over the upper Midwest from Canadian wildfires, which should only persist over the region through the day Monday as a longwave upper-level trough loiters over the northeastern CONUS. On the western side of this trough, northerly flow aloft is ushering all of this smoke southward. Both the RAP and HRRR smoke models suggest that not a lot of smoke is expected to mix down to the surface today due to a lack of deep boundary layer mixing, but some deeper mixing to around 800 mb per the 01.12z NAM and GFS on Monday could lead to some mix-down of the smoke, which could result in minor reductions in air quality. In terms of temperatures, high temperatures will likely be a hair cooler than what some guidance indicates due to the smoke, but warmer than average conditions are still expected. Tonight`s lows should only dip to the middle to upper 50s for most. Monday`s highs should be very warm, thanks to the aforementioned high pressure departing the region, leading to southerly return flow/warm air advection. The latest ECMWF EFI for high temperatures on Monday is now showing a larger footprint for values between 0.8 to 0.9 than previous runs, with a few isolated spots exceeding 0.95. This suggests a pretty strong signal for very warm conditions Monday. 850mb temps in the mid to upper teens C will help push highs into the upper 80s, with a few locations potentially reaching around 90 degrees. However, with dewpoints only in the mid 50s to near 60, the heat indices will closely match the air temperature. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Issued at 207 PM CDT Sun Jun 1 2025 For Tuesday through Thursday, a more active pattern is expected as an upper-level trough and attendant cold front approaches the region. Abundant moisture from the Gulf should advect higher PWAT values around 1.7 to 2.0 inches per the GEFS ensemble plumes by Tuesday afternoon. This first trough should phase in with a southern stream trough coming from the southwestern CONUS, arriving on Thursday. Combined, these two waves will result in a prolonged period of rainfall chances Tuesday through Thursday (though not a complete washout), with a soaking rainfall expected across the area. Chances of rain will be highest Tuesday PM into Wednesday (70-90 percent). Looking at a 72-hr period from Tuesday through Thursday, NBM exceedance probabilities of one inch or more of total rainfall is between 60 to 80 percent and between 30 to 50 percent for two inches or more. Although we are outlooked for a Slight Risk (level 2 of 4) for excessive rainfall/flash flooding in eastern IA into west- central IL and northeastern MO by WPC, thinking that the flooding threat will be mainly isolated to urban areas as already-planted crops/fields should be able to soak up the moisture pretty efficiently. However, if copious rainfall occurs over urban areas, there could be some street flooding, especially in areas of poor drainage. In terms of severe weather potential during this active period, the main focus continues to be on Tuesday as we are currently outlooked by SPC in a Slight Risk (level 2 of 5) for most of the CWA. While the various ML guidance paints a Slight Risk equivalent for severe weather for most of the CWA, uncertainty remains on the northward extent of the severe potential with this system as mid-level lapse rates appear to be fairly meager (<6 C/km), and the degree of boundary layer heating could be limited within the plume of higher moisture air. It`s possible that the Slight Risk could be cut back for our CWA, but we will see how/if subsequent outlooks change. && .AVIATION /00Z TAFS THROUGH 00Z TUESDAY/... Issued at 626 PM CDT Sun Jun 1 2025 Eastern Iowa TAF sites sit on the western edge of high pressure centered across Illinois, Indiana, and western Iowa. Clouds are mostly around 25000 ft with smoke across the area from wildfires in Canada. The smoke is not expected to make it to the surface and reduce visibility. Winds are forecast to become light and variable this evening before increasing to 10 knots by 16 UTC on Monday with gusts up to 20 knots through the afternoon. Conditions are forecast to be VFR through the period. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...Schultz LONG TERM...Schultz/Uttech AVIATION...Cousins