textproduct: Kansas City/Pleasant Hill

KEY MESSAGES

- Multiple Rounds of Showers and Thunderstorms Today Through Thursday Morning

- Flood Watch Issued for Central Missouri Tonight through Thursday Morning

- Brief Break from 90s Temperatures, But Warm Up Possible Over the Weekend Again

DISCUSSION

Issued at 356 AM CDT Wed Aug 5 2026

Mid-level trough axis this morning is currently positioned across the eastern Plains, and will continue to shift eastward with additional digging toward the lower Missouri River Valley. Several pockets of upper-level divergence has been providing extra lift across much of the Upper Midwest and middle Mississippi River Valley over the past 12-18 hours. Surface cyclone has continued to deepen across parts of the Central and Southern Plains, with surface troughing extending northeastward into northern Missouri. This area of surface troughing is also where a stalled thermal boundary currently sits. And overnight convection in eastern Nebraska, northwest Missouri, and western Iowa has provided precipitation drag on the cool side to further reinforce the temperature gradient associated with it. This will set the stage for favorable forcing Wednesday afternoon and evening for new development. For the remainder of the morning, a few weak mid-level vort maxima are set to track across the area, which may provide enough mid-level lift of a warm and moisture boundary layer along and ahead of the frontal boundary to generate some shower activity. 06z HRRR and other CAMs have been keeping morning activity more in northern Missouri to Central Iowa, where stronger surface convergence has been present along the boundary this morning. This area has also seen few mid- level disturbances that provided further lift, compared to areas south of Hwy. 36 this morning. The NAMNest is the only model that tries to generate stronger convection further south during the morning hours, but current radar trends seem to support more of a HRRR and even RRFS solution. Wind shear, especially with the low- level jet could help organize convection this morning in our northern zones, but the better kinematic support for that is currently concentrated over Central Iowa. We will need to watch rainfall rates if anything does move southward, especially in Adair County MO and surrounding areas that saw locally heavy rainfall late Tuesday evening.

Most of the redevelopment and threat for severe weather on Wednesday afternoon and evening is going to heavily depend on seeing some clearing, and having enough boundary layer destabilization to get stronger storms going. We should see the surface cyclone move slightly eastward, with surface troughing and associated pressure falls moving further into the lower Missouri River Valley. Differential heating potential along the boundary will also play a role in convergence. Stronger theta-e advection this afternoon and evening should help areas southeast of the thermal boundary reach MUCAPE values between 1500-2000 J/kg. Some solutions that completely clear out morning activity push SBCAPE values to near 3500 J/kg. Getting activity to initiate with plenty of low-level and even mid- level kinematic support should not be a problem. And while destabilization occurs and increasing CAPE values, lapse rates based on model soundings on the warm side of the boundary are not overly steep. Selecting a few points throughout the forecast area, we are not seeing any lapse rates get much steeper than 6C/km. This may end up being the limiting factor to getting stronger cores this afternoon, despite 0-6km bulk shear values between 30-40 kts (potentially nearing 50kt later Wednesday evening in Central MO). While the kinematic parameters may initially look favorable for supercell storm mode, the broadscale lift support by the approaching 500mb vort maxima may lead to interference, yielding widespread multicells through the afternoon. As for storm evolution, there looks to be 3 distinct rounds of convection initiation. The first is already occurring this morning in Iowa and northern Missouri. The potential for this to move southward across the rest of the forecast area appears to dwindling, though there are few light radar returns over central Kansas that will need to be monitored. After 18z today, when there will be some destabilization (the magnitude of it will largely depend on any cloud clearing if we are able to get some subsidence after any more rain showers). Multiple CAM solutions develop multi cells from eastern Kansas to Central Missouri. Based on simulated radar reflectivity fields, the stronger cores between 18-22z this afternoon are closer to Central MO. And this may be because those areas may be further removed from cloud cover that is otherwise closer to the boundary, and perhaps larger surface pressure fall drop through the afternoon. However, lapse rates from soundings near the environment CI there are still not overly impressive, and any cells that develop will have to tap into the shear to organize. With the moisture that is present (PWATs ranging between 1.75 to nearly 2.00 inches on the warm side of the boundary), precipitation loading may be enough to create stronger vertical pressure gradient perturbations that could lead to localized downburst winds to around 60 MPH. Expect the KDP values from dual-polarization to be quite high with large liquid water content in these storms. This precipitation loading possibility may extend westward into the KC metro, especially with forcing along the boundary. However the thermodynamic environment may not as great. Any activity that develops in the afternoon will have a battle between favorable forcing and favorable thermodynamics.

Later in the evening after sunset, as the low-level jet starts to ramp up (nearly 40kts in some CAM guidance), additional convergence along the thermal boundary is likely to initiate, and this may develop closer to the KC metro unless the boundary shifts eastward or surface pressure fall trends drastically move toward eastern Missouri. Lapse rates continue to very rather poor, but with theta-e advection through the afternoon, overall instability should be there. Thunderstorms in the evening are more likely to be elevated, unless there is a dramatic modification to the boundary layer prior to sunset. As the low-level jet kicks, the HRRR and RAP shows impressive effective-inflow layer shear into thunderstorms that develop, that will once again be able to help them organize. However, given the the weaker lapse rates, it may take longer for storms to congeal and organize before that reach potential severe strength, and therefore, makes the severe threat more favorable for areas east and southeast of KC metro even through this evening. Wind gusts will continue to be the primary threat, with precipitation loading helping to produce winds, even if the thunderstorm bases are elevated. As the front then moves eastward through the night, additional H5 short-wave perturbations may continue to provide lift and post-frontal shower/storm activity through Thursday afternoon. Most of the post-frontal activity, while it may still have access to healthy moisture, will likely be lacking sufficient instability to continue any kind of severe threat. However, if additional rainfall activity falls over areas again, this may lead to hydrology issues.

A Flood Watch has been issued for central Missouri for Wednesday evening through Thursday morning. The airmass ahead of the boundary is characterized by PWATs between 1.75 and 2.00 inches, along with warm cloud depths attempting to push about 4km, and skinny CAPE thermal profiles (thanks to the weaker lapse rates). While it is unclear if training storms along the boundary will become problem, multiple rounds of showers even if a few hours apart could still lead to rainfall rates between 1.5 to 2.0 inches per hour, especially in central Missouri. 00z HREF mean QPF has between and 1 to 2 inches of rainfall east of Hwy. 65 tonight through Thursday morning. Probability matched mean (PMM) values retain maximum pockets exceeding 3", and other ensemble guidance depicts some potential for as much as 3-5 inches of rainfall in Central Missouri that could occur within a 3 hour period. This is the reason for issuing the Flood Watch across Central Missouri. For areas further west, heavy rainfall is still likely. However, rural areas that have been dry should be able to handle a couple of inches of rainfall. And with the signal in the HREF and other CAM guidance not being as strong for exceeding 3 inches of QPF, did not draw the Flood Watch back as far west with this initial issuance. If we see stronger cores initiate this afternoon further west, and still expect evening development along the low-level jet to bring more rainfall, westward expansion may become possible. But as of right now, even maximum QPF values from ensemble suites is not as threatening in our west as it is in our eastern zones. As for the KC metro and flooding, the overall QPF signal is for only around 1.0 to 1.5 inches over the event. However, if we get activity further west, and see this fall within 60 to 90 minutes, we may see typical urban flooding issues arise, including some of the flashy creeks streams in the metro.

A break from rain shower activity is expected Thursday Night into early Friday, but another short-wave perturbation may bring more rain back to parts of the forecast area. Ensemble trends though the remainder of the weekend have backed off on rainfall potential, compared to output from a few days ago. However, after the relief from temperatures on Thursday, if the ridge over the western CONUS continues to build, we may see strong WAA that helps to send temperatures back into the 90s over the weekend, and that may continue into the next work week.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1235 PM CDT Wed Aug 5 2026

Patchy showers continue across the region this early afternoon, and will likely linger through mid to late afternoon. Additional shower and thunderstorm development is likely by around 4z Thursday, with periods of moderate to heavy rain and reduced VIS possible along with MVFR CIGs. Rain should come to an end after 12z Thursday, with MVFR CIGs continuing through the remainder of the morning hours.

EAX WATCHES/WARNINGS/ADVISORIES

MO...Flood Watch from 7 PM CDT this evening through Thursday morning for MOZ007-008-016-017-024-025-032-033-039-040- 045-046. KS...None.