textproduct: Kansas City/Pleasant Hill

KEY MESSAGES

- Rain Showers and Strong Thunderstorms Tuesday

- Strongest Activity and Severe Potential Focused Tuesday Late Evening and Overnight

- Seasonable Temperatures to End Week

DISCUSSION

Issued at 320 PM CDT Mon Aug 17 2026

Mid and upper-level flow is zonal across the Central CONUS today with a ridge axis over the Intermountain West. Surface anticyclone currently sits underneath it which has presented the mild weather conditions for Monday. There are several short-wave perturbations over the Rockies though that will result in dCVA over the Front Range and Lee Cyclogenesis, with pressure falls extending eastward into the Plains starting on Tuesday morning. Convection will likely be occurring over the Central Plains and attempt to move eastward toward the area.

For the forecast area Tuesday, H5 height falls will slowly continue through much of the day as surface cyclone strengthens over the High Plains of Kansas. Surface pressure falls remain progged to expand eastward into the lower Missouri River Valley, which will provide an increase in convergence heading into the afternoon. The short-wave perturbations will also aid in providing deep layer shear, gradually increasing to 35 to 40 kts of 0-6km bulk shear by the afternoon. A cold front is expected to develop and be positioned on the backside of the developing cyclone. Surface winds throughout Tuesday afternoon will turn more southerly, and provide stronger theta-e transport, resulting in increasing dewpoint temperatures. Convection over the Plains, whether or not it develops and propagates downstream, is largely going to determine what will happen in the afternoon across eastern Kansas to Central Missouri. Current CAM guidance has the organized convective complex over Nebraska decaying before reaching northwest Missouri. However, this starts to send an outflow boundary southeastward into the forecast area, that could provide further initiation downstream. If activity is able to develop along this, there may be enough deep layer shear to help try and organize it. However, very uncertain how much CAPE will be there in the presence of any outflow boundary potential. From the 12z HREF, MUCAPE values prior to 18z Tuesday afternoon struggle to climb much above 750 J/kg. Cirrus clouds advecting from overnight convection in Nebraska may slow the rate destabilization into northeast Kansas and Central Missouri, which would limit the severe threat if anything develops after 12z Tuesday morning in the forecast area. As of right now, the expectation is that there will be scattered shower and storm activity, but with a limited severe threat is any at all. We will need to pay close attention to instability trends Tuesday morning and afternoon. If the boundary layer is able to rapidly destabilize, Tuesday afternoon shower activity could deepen and become more robust.

Attention then turns to the Tuesday evening, and heading into the overnight hours. Surface pressure falls will continue as the surface cyclone propagates eastward toward the lower Missouri River Valley. Continued mid-level height falls will also provide more broadscale lift across much of the region, with southerly winds continuing to provide theta-e advection, which should help bump up CAPE values substantially. The timing still remains uncertain, and occurrence still conditional, as afternoon activity and remnant outflow boundary placement looks to largely be in control of the mesoscale environment. CAM guidance continues to depict the new development of storms in central and eastern Kansas between 23-01z in the evening, largely tied to the cold front and mid-level lift from the mid-level short-wave vort maxima. This will then move toward the southeast along the axis of increasing surface pressure falls. These storms are expected to have more instability to work with. However, what is uncertain is if storms will be surface based, or if they will become more elevated. Central Kansas and areas just west of the forecast area will have the best chances for isolated and discrete convection after peak heating. Unsure if discrete activity will continue into far eastern Kansas and western Missouri. If storms remain discrete and surface based after 00z as they move toward the east-southeast, backing surface winds and curved low-level hodographs can favor the development of supercells. There is enough SRH that could support a tornado threat, along with healthy mid-level CAPE through the hail growth zone allowing for larger hail stones, and the damaging wind gusts. Our western zones seem to favor the most potential for this threat if it is realized, while the potential for discrete convection and supercell storms east of Interstate 35 is greatly diminished. If the discrete convection remains well west of the area, the low-level jet is expected to congeal any storm activity over Central Kansas into an MCS. 0-3km bulk shear between 40-50 kts is possible heading into the evening, providing plenty of support to help organize an MCS and maintain a healthy balance for continued development of new cells and MCS expansion. As a result, even if storms are more elevated, stronger cold pools will be supportive of damaging wind gusts. Depending on the how the updraft/downdraft convergence zone orients to the strong 0-3km shear vector, may favor mesovortex generation and some QLCS tornado potential. However this is highly conditional on how an MCS propagates, and how long it is maintained. Uncertainty in its maintenance increases for the southeastern portion of the SWODY2 Slight Risk. We should be able to get better handle on how late Tuesday and early morning Wednesday convection might evolve, once we see how activity occurs after 12z on Tuesday. With respect hydro, there is potential for some areas see over 2 inches of rainfall by early Wednesday morning. This may result in some flooding issues across the area, and there is a slight risk for excessive rainfall. However, given the uncertainty with rainfall amounts earlier Tuesday, there is not enough confidence to issue a Flood Watch at this time.

By late Wednesday morning, most of the robust activity should push east-southeast out of the forecast area, though there may be some left-over mid-level lift that could continue scattered shower activity into the early afternoon hours of Wednesday. For the remainder of the week, northwesterly flow will help keep temperatures cooler to what we have seen in recent week, with temperatures near seasonable normals. H5 ridge axis is expected to amplify over the western CONUS, but disturbances over Canada may send down a few mid-level vort maxima through the week that will be capable of generating some shower activity.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1217 PM CDT Mon Aug 17 2026

High pressure will keep weather conditions mild this afternoon and evening. A few cumulus clouds will be present during the afternoon hours. Rain showers and thunderstorms are expected Tuesday, but are expected to hold off until after 18z tomorrow, outside of the current TAF period.

EAX WATCHES/WARNINGS/ADVISORIES

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