404 FXUS63 KEAX 250256 AFDEAX Area Forecast Discussion National Weather Service Kansas City/Pleasant Hill MO 956 PM CDT Thu Jul 24 2025 .KEY MESSAGES... * Dangerous flash flooding possible tonight from eastern KS into western and northern MO. This includes the KC Metro area. - There is potential for extreme rainfall amounts of 9-12". - Exact location is uncertain but most likely from eastern KS into western MO. * Flooding potential continues Friday afternoon - Saturday Morning, mainly for northern Missouri. * Hot and humid conditions return Saturday and Sunday, then persist through the middle of the next week. && .UPDATE... Issued at 956 PM CDT Thu Jul 24 2025 Updated the forecast to adjust PoPs for the ongoing convection and into the available newer guidance through the overnight. This results in some increase in PoPs in our east over the next couple of hours, with a decrease over eastern KS and northwest MO during the same time period. Then blended that with some of the latest guidance that keeps PoPs in the likely to definite range overnight. Current trends also require some adjustments to QPF. Generally lowered QPF ion eastern KS and western MO through 06Z and increased it further east to match current trends better. After midnight, generally lowered QPF as well though still should be a broad 1-2 for the area with locally higher amounts. The big monkey wrench in things is the earlier convection produced a significant cold pool which is currently decreasing coverage of storms around the KC area. However, precipitable water values remain extremely high, 2" to nearly 2.5", across the forecast area. With several thousand J/kg of MUCAPE still available, and the LLJ to interact with all of this, still think potential for flash flooding exists through the overnight hours. Think we will see an expansion northward of the ongoing convection to our southwest into east central KS and western MO in the 06Z to 12Z time frame. && .DISCUSSION... Issued at 227 PM CDT Thu Jul 24 2025 This afternoon - Friday Morning: Ingredients are coming together for dangerous flash flooding from eastern KS into western and northern MO. First, precipitable water values are extremely high. Available guidance shows precipitable water values ranging from roughly 2.25" to 2.5" at 00Z tonight into the overnight. When comparing those values for eastern KS and western MO to the climatology for 7/25 00Z TOP sounding, that would break the daily record and be in the top 20 for recorded values. For perspective, the return interval for this type of moisture for this time of year, based NAEFS climate period of 1979 to 2009, is every 5 to 10 years. The GEFS return interval, which uses a later interval is closer to every 5 years. So this is abnormally high moisture content for this time of year for this area. Second, moderate to strong moisture transport will develop tonight as the low-level jet strengthens. Models show moisture transport magnitudes of 200-225 gm/kgs into eastern KS and western MO. This moisture transport intersects the third ingredient, a stalled boundary that will be in the area. That boundary will act as a focus for storm development and is responsible for most of the uncertainty with this forecast. The location of this boundary will likely be in the vicinity of of the Highway 50 to Highway 36 during the height of the event, but may drift northward with the strengthening low-level jet. Given this likely location, that corridor has what looks like the greatest potential for dangerous flash flooding. Model QPF is varying greatly with this event, both in location and amount. But some of the highest guidance (Canadian and 3km NAM) show 9-12". The Canadian on the southern side of the KC area and the 3km NAM on northeast side of the KC area. These models are the worst case scenario for rainfall amounts given the setup, but also can`t be completely ignored either. Other models cut this amount in half and remain scattered with their placement. Still, putting 2-5" of rain through the KC area, given very low flash flood guidance values from several recent heavy rain/ flash flood events, will cause excessive runoff and flooding to occur. A moderate risk for excessive rain has been placed over the area as result of these antecedent conditions and the good potential for heavy rainfall in the area from this afternoon through tomorrow morning. Friday afternoon - Saturday: The overall pattern tends to shift northward Friday afternoon into Saturday. Though there remains some guidance that hangs the initiating boundary south and as a result places additional storms and heavy rain further south. This can`t be completely ruled, especially if boundaries don`t lift northward as most guidance suggest. However, most guidance shifts the threat of heavy rain across northern MO and points northward so have placed higher PoPs and QPF further north as well. The pattern still shows high precipitable water values, strong moisture transport into the area and convergence along a boundary somewhere from northern MO, likely north of Highway 36, into southern IA. This northward shift of the threat adds some potential for the need for heat headlines in our south tomorrow. Based on my current forecast heat index values of 100 to 104, lower confidence in that even occurring, and that we`ve had several days of heat in those areas, would like to stick closer to criteria and have more confidence for that part of the forecast. So will only keep the advisory going through 7 tonight and not extend it into Friday. Saturday may be a different story as low-level flow becomes more southwesterly, allowing temperatures to climb back into the low 90s along and south of the Missouri River. Forecast max heat index values are around 105 to 107 in this area. So heat headlines may be needed with later forecasts. Sunday and Beyond: Saturday looks like just a precursor for the heat that arrives next week. Models show upper-level ridging expanding northward into the region with 598 dam 500mb high sitting just to our south. This will lead to very hot temperatures across the forecast area with highs likely in the mid to upper 90s, which is about 5-10 degrees above normal for this time of year. Factor in the humidity, with daily afternoon dewpoints in the mid to upper 70s, and we`ll likely see heat index values in the 105 to 110 range from Sunday through Tuesday and possibly into Wednesday. Heat headlines will be needed at some point to address this growing potential for dangerous heat. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 627 PM CDT Thu Jul 24 2025 Another cluster of scattered showers and thunderstorms has developed across eastern KS, but are more likely to remain just south of the terminals through this evening. Scattered to widespread thunderstorms develop along a boundary across all terminals around 6z and continue into Friday morning before diminishing by 12-15z. There is uncertainty where the heaviest axis of rainfall will setup, resulting in lower cig and vsby reductions. At least MVFR conditions are progged across all terminals, but intervals of IFR conditions will be possible with training thunderstorms. && .EAX WATCHES/WARNINGS/ADVISORIES... MO...Flood Watch through late Friday night for MOZ001>008-011>017- 020. Flood Watch through Friday morning for MOZ021>025-028>033- 037>040-043>046. KS...Flood Watch through late Friday night for KSZ025-102. Flood Watch through Friday morning for KSZ057-103>105. && $$ UPDATE... DISCUSSION...CDB AVIATION...