textproduct: Kansas City/Pleasant Hill

KEY MESSAGES

- Hazardous / prolonged heat continues through the weekend and into next week. - Extreme Heat Warning remains in effect through 8 PM Saturday area wide and through 8 PM Tuesday for areas along and south of a line from St. Joseph MO to Boonville MO

- Chances (20 to 35 percent) for thunderstorms Sunday afternoon and evening, with greatest chances tending to be over northern Missouri.

DISCUSSION

Issued at 315 AM CDT Sat Sep 5 2026

The general pattern evolution across the CONUS remains high confidence. The LREF 500mb spreads are predominantly < 3 dam across CONUS until mid-week. Even then, majority of the increasing spreads are understandably seen arcing over the Central and Southern Plains, keeping area 500mb spreads <= 3 dam through next week. What does this mean? Since we are currently entrenched within mid-level ridging, it generally means well above normal temperatures stick around through the forecast. For general reference, 30-year normal highs are around the low to mid 80s this time of the year. Of course, 500mb pattern evolution does not tell the whole story, and there are some details within the forecast, aside from heat, worth noting, including storm chances, backdoor cold front, and more substantial relief later in the forecast.

The existing Omega block pattern is expected to largely remain locked in place through the weekend. While this keeps peak heat potential similar to previous few days, in the mid to upper 90s, there will be an opportunity for that temperature forecast to bust this weekend. Today will not be that day though with light southerly flow and a 700 mb temp ridge nosing into the area that will keep any air-mass convection from developing. Those chances should remain relegated more toward the Ozarks portions of the state where 700mb temps are a couple degrees cooler and may allow convective temps to be achieved. So mid-upper 90s, even touching 100 possible, for much of the area today. By the latter portions of today, a surface high dropping into the Great Lakes region will begin to push a backdoor cool front (generous wording there) into NE Missouri. This will do a couple of things. Most notably it will drop Sunday highs into the upper 80s and lower 90s for NE and E Missouri. Unfortunately it tends to stall out as it pushes westward across the state, providing limited or no relief to areas W and S of a line from around Maryville MO to Columbia MO. This results in the end of the Extreme Heat Warning for portions of N/NE Missouri Saturday evening, and continuing further south through Tuesday. Concurrently, 700mb temps will fall across the area, setting the table for the potential for some scattered thunderstorm activity near the surface boundary and westward where this cooling may allow scattered air-mass convection to be achieved. Additionally, shower/storm activity rounding the mid- level ridge may drop S/SE out of Nebraska/Iowa along the expected CAPE axis. Timing for all of this would be Sunday afternoon and into the evening. Wind profiles do not support organization, but a very dry sub-cloudbase layer could provide opportunities for evaporatively enhanced downdrafts. As hinted earlier, this too provides the chance for a busted temperature forecast in areas that see storms, especially if areal coverage of activity increases.

By late weekend and into the early work week, the Omega Block begins to break down in response to a Polar Stream trough pushing the New England cutoff low eastward. The western CONUS cutoff low will take advantage and begin to move E/NE itself, eventually yielding surface low development over eastern Montana and into the southern Canadian Plains. This will also act to push the mid-level ridge back eastward and generally begin to flatten. Unfortunately, no notable relief to the area, in fact a general brief resurgence of the heat as the 850mb temp ridge axis angles into the state. Expect temperatures Monday to be similar to Sunday, but surge back warmer a few degrees on Tuesday back into the upper 90s and around 100 for many. By Wednesday, the mid-level ridge flattens and a cold front will begin to approach the area from the north. This too is where uncertainty begins to increase with some varied timing in arrival time. Slower arrival may yield an extension of the Extreme Heat Warning one more day, but confidence is not quite there to extend with LREF and NBM MaxT spreads of 6 to 10 degrees. Higher confidence in relief (but likely still at least a few degrees above normal) by Thursday and to end the week though, including potential for some shower/storm activity in/around the front as well as shortwave activity.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 537 AM CDT Sat Sep 5 2026

Prolific VFR conditions across the sites through the period. Light variable winds early this morning give way to light southerly winds through the day time and eventually light easterly winds overnight tonight. Sustained wind speeds only to around 5 kts in most cases. FEW/SCT high level cloud cover at times.

EAX WATCHES/WARNINGS/ADVISORIES

MO...Extreme Heat Warning until 8 PM CDT Tuesday for MOZ020>022- 028>031-037>040-043>046-053-054. Extreme Heat Warning until 8 PM CDT this evening for MOZ001>008-011>017-023>025-032-033. KS...Extreme Heat Warning until 8 PM CDT Tuesday for KSZ025-057-060- 102>105.