textproduct: Kansas City/Pleasant Hill

KEY MESSAGES

- Shower and storm chances (30-50%) this afternoon and evening. There is a SPC Marginal Risk (Level 1 of 5) for severe storms for most of the area. The main hazards are damaging wind gusts, hail, and locally heavy rainfall.

- Hazardous and prolonged heat continues. Extreme Heat Warning remains in effect until 8 PM tonight for areas generally south of US-36 and until Tuesday at 8 PM for the Kansas City Metro and some surrounding counties.

DISCUSSION

Issued at 145 PM CDT Sun Sep 6 2026

Other than enhanced 250 mb winds on the leading edge of the Pacific Northwest trough, 12Z upper-air observations show that the overall synoptic pattern is mostly unchanged with the Omega-block still clearly evident. However, beginning this afternoon and evening, the thermal ridge will begin to erode as the region of enhanced winds continues to intensify into a 120+ kt jet streak over the Intermountain West on the upwind side of the ridge. This will provide sufficient energy and momentum for the stagnant Pacific Northwest trough to carried eastward, ultimately deamplifying the ridge. Although it will be a days-long process, this transition is high confidence with both the HREF and LREF 10th to 90th percentile spreads showing a height difference of only about 1-3 dam through Tuesday with the ridge being fully suppressed by Wednesday.

Overnight Saturday into Sunday, a backdoor cold front moved through much of the CWA; latest observations and surface analysis suggest that this boundary has stalled just west of the MO/KS border. Temperatures are expected to top out in upper 80s/low 90s across northern MO today behind that boundary. Further south where the Extreme Heat Warning remains in effect, temperatures are anticipated to be similar to yesterday in the mid/upper 90s and heat index values around 105F or greater.

As we head into the afternoon and evening hours tonight, the evolution of the environment will need to be monitored closely. Compared to the previous forecast cycle, the likelihood of storm development in the afternoon has increased (now 30-50% chance generally along and west of the I-35 corridor). Cloud cover associated with weak convection and showers to our north and west have struggled to make it into Missouri. With abundant sunshine and solar heating, considerable destabilization is underway. By late afternoon, we could see up to 3500 J/kg MLCAPE and an eroding 850mb warm nose. Additionally, an outflow boundary from decaying showers in central Kansas has been noted throughout much of the late morning hours from KTWX. Depending on how far east this outflow progresses, it could be a focal point for storm development this evening. For what it's worth, the most recent runs of the CAMs do appear to be initiating convection in a comparatively more organized manner compared to the disorganized clusters noted in earlier runs which does suggest some boundary interactions. SPC has maintained the Marginal Risk (Level 1 of 5) for severe weather in our area this afternoon and evening with the main threats being hail and damaging winds. The severe threat appears greatest during daylight hours today when buoyancy is better for lofting hailstones and sub-cloud layer profiles are more suggestive of downburst wind potential. Forecast PWATs are also near the top of climatology around 1.9" to 2.1" so isolated pockets of heavy rainfall will also be possible. WPC has a Slight Risk (Level 2 of 4) of excessive rainfall in northwestern Missouri today and tonight. After sunset, expect a general downtrend in the severe threat with any ongoing storms though the hydro threat may continue with additional showers/storms moving into the area, mainly in northwest Missouri.

More uncertainty exists with the late evening and overnight potential for showers and storms as it is more dependent on factors across the Northern Plains where convection has been ongoing for much of the morning and early afternoon. A shortwave helping sustain this activity will continue eastward tonight which may encourage continued development. Notably, the steering flow shrouding this shortwave has a strong northerly component that could draw storms into northern Missouri sometime after dark (roughly a 20-40% chance). There would be a much lesser severe threat with these storms, but heavy downpours and some gusty winds would still be possible. Showers/storms should weaken and decay with time, but some may linger through early Monday morning.

Areas across northern Missouri can also expect "cooler" high temperatures in the upper 80s and low 90s once again on Monday, with areas between the US-36 and I-70 corridors in the low/mid 90s. South of I-70 and near the MO/KS border, temperatures are expected to remain in the mid/upper 90s. The Extreme Heat Warning continues for the Kansas City Metro and south until 8 PM on Tuesday where there is higher confidence in 105F heat index values. Additional heat headlines may need to be considered for portions of central Missouri on Tuesday and Wednesday but will defer to future forecast cycles as the timing of a midweek cold front remains unclear. Currently, the most likely timeframe for the front to move through looks to be overnight Tuesday into early Wednesday. If this holds true, a headline on Wednesday would probably be unnecessary but a headline may still be warranted in central MO on Tuesday. By Thursday, widespread relief from that frontal passage will arrive with temperatures in the low/mid 80s across northern Missouri and northeastern Kansas and in the mid/upper 80s around and south of I- 70. Several more rain and storm chances are in the future, specifically on Wednesday, Thursday, and over the weekend. Shear certainly looks sufficient to support some organized convection, but there are still too many details to be ironed out before any definitive statements can be made.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1228 PM CDT Sun Sep 6 2026

Currently VFR at all terminals under some passing cirrus with light southeasterly winds. These conditions should generally persist through the period, although there will be a chance for showers and thunderstorms in the area late this afternoon into the evening hours and again late tonight, which are currently handled by two PROB30 groups. Brief periods of heavy downpours leading to reduced VIS will be possible with any storm that may impact the terminals.

EAX WATCHES/WARNINGS/ADVISORIES

MO...Extreme Heat Warning until 8 PM CDT Tuesday for MOZ028-029-037- 043-053. Extreme Heat Warning until 8 PM CDT this evening for MOZ020>022-030-031-038>040-044>046-054. KS...Extreme Heat Warning until 8 PM CDT Tuesday for KSZ025-057-060- 103>105. Extreme Heat Warning until 8 PM CDT this evening for KSZ102.