textproduct: Kansas City/Pleasant Hill

KEY MESSAGES

- Hot and Humid Saturday Afternoon

- Thunderstorms This Evening through Overnight; Some Severe Storms Possible

- Cooler After Sunday

DISCUSSION

Issued at 308 AM CDT Sat Sep 19 2026

The trough over the Intermountain West will send a few vort maxima into the Central CONUS as we head into Saturday, which will provide gradual H5 height falls across the area. The dCVA associated with this will continue to deepen a surface cyclone which is beginning to expand eastward, with surface pressure falls currently reaching into eastern Kansas and eastern Nebraska. The warm front that moved through today made into the far northeastern zones of the forecast area, and extends into northwest Iowa, while the cold front trailing this system is currently positioned from roughly Omaha, Nebraska southwestward toward Colby, Kansas as of 08z this morning. Radar early this morning is starting to show activity in southeast Nebraska and northwest Missouri near the Triple Point, co-located with an area of upper-level divergence. Off and on rain showers and perhaps some scattered thunderstorms will develop as the day progresses through early afternoon, but should remain mostly sub- severe in our forecast area. Continued low-level southerly flow will provide WAA keeping air temperatures in the mid 90s today, with dewpoints reaching the upper 60s to lower 70s. The main focus for strong thunderstorm activity is favored after 23z this evening, mainly along the cold front as the primary forcing mechanism. Ahead of the cold front, most of the eastern Plains and lower Missouri River Valley will have plenty of daytime insolation that will work to destabilize the boundary layer. As the main short-wave trough moves overhead, mid-level cooling will promote steeper mid-level lapse rates that will pave the path for stronger updrafts, especially as this sits on top of warm moist boundary layer. As the primary short-wave trough axis moves through, stronger mid-level jet streak should help to provide increasing deep layer shear, with 0- 6km bulk values around 30-35 kts, and some deterministic guidance does show this overspreading parts of the warm sector and extends behind the cold front. This solution is a bit further east than what previous numerical model guidance was suggesting the past couple of days. Based on 00z HREF guidance, the warm sector appears capable of SBCAPE above 1500 J/kg across much of the forecast, with a concentrated axis of near 2500 J/kg from near Emporia KS northeast toward south-central Iowa, just clipping the Kansas City Metro northland. The initial development of the strongest storms is expected over Central Kansas after daytime heating. West of the forecast area, initial storms will remain discrete, and with some directional shear in the first kilometer or two, could see a few supercells develop out there. However, by the time strongest convergence along the cold front enters our eastern and northeastern Kansas Counties, the deep layer shear vector is progged to orient more parallel to the boundary and with the low-level jet increasing, is expected to result in upscale growth into some kind of QLCS or MCS like mode. Depending on the amount of boundary layer mixing that occurs and how quickly the front propagates, RAP soundings on the warm side of the boundary have been hinting at inverted-v like structure below the progged cloud bases, with DCAPE pushing above 1100 J/kg. This type of environment would favor downburst potential with newer updrafts. But then as upscale growth continues, stronger cool pool development may lead to strong outflow winds. Current expectation is that the large hail threat will mainly be confined to areas well west of Kansas City tied to where a supercell storm mode is more likely. However, if along the front we have more broken line segments and still get new updraft development, the steep mid-level lapse rates and healthy CAPE profiles through the hail-growth zone may help get hail stones up to around golf ball size. Heading into the overnight hours, even after FROPA, another area of mid-level height falls will promote additional lift, and is expected to keep shower and thunderstorm activity going. While the severe hail and wind threat may start to diminish, especially as the front moves toward Central Missouri, continued rainfall may augment hydro and flooding issues that started earlier this week, especially for areas north of the Kansas City Metro that were hit hard this week. HREF proability-matched mean QPF values are roughly around 1 inch, but there are concerns that these values could be exceeded if this boundary stalls. Current deterministic CAM guidance suggests that the stronger storms and showers will be fairly progressive enough to limit training, with stratiform rain trailing the main system having fairly low hourly rainfall rates. With most guidance suggesting that showers will start to weaken as they cross into Missouri, have not issued a Flood Watch. We will note that some rivers and streams are running at elevated levels from the heavy rain that occurred earlier this week, and if rainfall above 1.00 inch falls into those basins, may send some rivers back to flood stage.

Sunday, the main cold front will pass through by the early evening. Southern zones in the forecast area may still hit the mid 80s for temperatures, while northern Missouri and northeast Kansas will be in the upper 60s and lower 70s for daily highs. Continued H5 disturbances may provide more rain shower activity, but thunderstorm potential should be limited as there does not appear to a great opportunity for destabilization. We may see more rain shower activity reinvigorate early Monday as H5 closed-low sits over the Upper Midwest, but uncertain how much lift that will provide for the lower Missouri River Valley. The next work week will feature much more seasonable afternoon temperatures.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/

Issued at 1150 PM CDT Fri Sep 18 2026

VFR conditions are expected across the region for the majority of the TAF period before TSRA chances increase in the final 6 hours. For much of Saturday, anticipate southwesterly surface winds before becoming more westerly/northwesterly in the evening. Thunderstorm chances increase across eastern Kansas and western Missouri around/after sunset Saturday evening. Decided to go with PROB30s for all TAF sites given some remaining timing/placement uncertainty but the PROB30 groups do account for the most likely TSRA window for this TAF period. With storms, VIS could drop to MVFR. Behind the cold front, winds to shift out of the north with CIGs falling to MVFR or lower...this change looks most likely after 06Z Sunday, but a slightly earlier progression of the front could lead to shifts in the closing hours of the TAF period.

EAX WATCHES/WARNINGS/ADVISORIES

MO...None. KS...None.