textproduct: Kansas City/Pleasant Hill

KEY MESSAGES

- Warm Today

- Rain Showers Northern Missouri Late Tonight

- Showers and Thunderstorms Spread Across The Area Wednesday, Continue into Thursday

DISCUSSION

Issued at 516 AM CDT Tue Aug 4 2026

What is left of the mid-level ridge axis has passed into the Great Lakes Region, which has left a WAA regime and higher theta-e transport into the lower Missouri River Valley. Short-wave trough and notable vort maxima over the Northern Plains and Canadian Prairie Provinces continues to move eastward, and has dug southward. This has resulted in upper-level divergence across the eastern Plains of the Dakotas toward the Upper Midwest. This pattern has also created a few mid-level perturbations over the Rockies, and has generated enough dCVA to provide lift to develop a surface cyclone. As this has deepened, surface pressure falls have already been extending eastward into portions of eastern Kansas this morning. Over the Northern Rockies this a strong surface anticyclone is developing behind the northern short-wave that has been breaking down the ridge pattern. This is pushing a cold front across the Plains, and overnight produced rain showers across parts of Nebraska and Kansas. So far those have been on a downward trend, but may be enough to result in sprinkle activity in far northwestern Missouri this morning and afternoon. We will likely see increasing cloud cover from the Plains activity later today, though we may get a period of subsidence that helps to create breaks in the cloud cover. With the deepening cyclone, low-level flow remains southerly, and will provide WAA boosting temperatures into the 90s across most of the forecast area. Far northwestern Missouri may stay in the upper 80s, as cloud cover may be more dense there. While there will increasing surface convergence, mid-level kinematic support will be lacking across forecast area for most of the afternoon, and therefore will maintain a mostly dry forecast. However a healthy instability axis is progged to setup across the area, that will set the stage precipitation late Tuesday Night, and spreading across most of the area Wednesday.

H5 height falls will pick up in pace late Tuesday evening, and the surface cyclone will begin to track toward Central Kansas, with inverted surface trough extending northeastward into north-central Missouri. The cold front will continue to trail the cyclone. Recent CAM runs have delayed the timing of rain shower activity late tonight, not entering northern Missouri until after 04z. Most of this activity is expected to be elevated, with a strong inversion in place. Mid-level cooling though may help to steepen 700-500mb lapse rates, and with increasing shear could try to help some activity organize. But overall, the environment late tonight may struggle to support stronger storms. Wednesday morning, we may start to see activity spread as the cyclone continues to deepen and surface convergence increases in strength. However, as the forcing moves eastward, the instability may be very meager. Currently the HRRR is only depicting a few hundred J/kg of CAPE throughout the warm sector, which may keep updrafts fairly week. However, deep warm cloud processes and PWATs in the warm sector of 1.65 inches could allow even general shower activity to very efficient with rainfall production, which may result in hydro issues even Wednesday morning. Attention then turns to the afternoon, to see if any clearing can occur after elevated morning activity. It is possible with the H5 pattern we may have be able to induce subsidence late in the morning and early afternoon, that will allow the boundary layer to destabilize, while surface cyclone continues to deepen and more moisture transport occurs into the lower Missouri River Valley. Surface pressure falls push east-southeast as the cold front continues track across the area. This will be the main forcing needed for activity. If the instability can be realized, bulk shear values near the cold front should be around 30-40 kts, aiding in helping convection become organized. However, with continued moisture transport and no EML, mid-level lapse rates may only reach between 5-6C/km, limiting the strength of updrafts despite having stronger wind shear. Precipitation loading though could be enough to produce wind gusts around 60 MPH with storms, especially if they occur during a rapid decaying phase of the storm. Overall CAPE profiles from model soundings late afternoon and into the evening on Wednesday are fairly skinny. However PWAT values ahead of the cold front are currently progged at over 1.80 inches with warm cloud depths up to nearly 4km, and may result in hydro and flooding issues, especially if multiple storms develop and train along the front. Amongst HREF members, heaviest QPF values are favored for northern and northeast Missouri. 00z HREF PMM values for QPF are nearly 2.5 to 3.0 inches in our northeastern zones, then drop off southward through central Missouri to the Interstate 70 corridor. There is still uncertainty with where the heavier QPF axis may end up though, as some of the 06z CAMs are not in agreement with each other on the placement of the surface pressure falls and where the best instability axis may be able to develop.

Another mid-level vort maxima helps to reinforce lift heading into Thursday, which will continue shower activity and isolated thunderstorms through the morning hours before pushing eastward. Instability should be very limited at this point, and possibly the surface cold front may be through the area, resulting in elevated post frontal convection. Cloud cover Thursday along with the passage of the cold front and cyclone should send temperatures back into the mid 80s across most of the area.

Weather pattern remains unsettled heading into the weekend, as H5 ridge attempts to build over the western CONUS again. However several short-waves may be able to move across the Central CONUS which could provide additional rainfall activity, though forcing does not look to be overly persistent with recent our recent model guidance runs. However strong WAA is possible that could send temperatures back into the 90s over the weekend, though cloud cover and rain showers will add higher uncertainty to the temperature forecast over the weekend.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 618 AM CDT Tue Aug 4 2026

Clouds will move eastward out of Kansas today, but most of the afternoon ceilings should be VFR. Light shower or sprinkle activity is possible in northwest Missouri this morning. Cold front will start to move closer late Tuesday through Wednesday morning, and we may start to see shower development early Wednesday morning at the TAF sites. Activity becomes more widespread past 12z on Wednesday.

EAX WATCHES/WARNINGS/ADVISORIES

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