textproduct: Kansas City/Pleasant Hill

KEY MESSAGES

- Dangerous heat and humidity combo is forecast today and Tuesday, with heat indices of 105-110 degrees. A Heat Advisory is in effect areawide from 1PM to 9PM today, and continues in portions of eastern Kansas and west-central and central Missouri through 7 PM Tuesday.

- A frontal boundary will bring a 30-50% chance of thunderstorms to far north-central and northeast Missouri early Tuesday morning, with the potential for some storms to be severe. - Additional chances for widespread thunderstorms return to the forecast Thursday into Friday, along with cooler temperatures and lower humidity levels.

DISCUSSION

Issued at 330 AM CDT Mon Jul 20 2026

Current Conditions & Synoptic Overview:

Ridging aloft spanned the western 2/3 of the CONUS and well into central Canada in previous days, but this ridge is beginning to be flattened by a shortwave trough pushing across the Canadian Prairie. 00Z upper air analysis indicates that a zonal upper-level jet is developing across the Northern Rockies and into the Northern Plains, cutting into the northern extent of the ridge, and the 00Z sounding from Glasgow, Montana has already observed 100+kts within this strengthening jet streak. A surface low has developed in Manitoba in conjunction with this upper-level disturbance, with a cold front extending south from the low into central South Dakota. Weak surface high pressure sits over the Great Lakes on the other side of a stationary front, which is spread from Sioux City, IA to the southeast through Bethany, MO and towards St. Louis. Widespread visibility reductions from wildfire smoke are apparent on regional observations in areas east of the front as the nocturnal boundary layer traps smoke near the surface.

Heat Today and Tuesday:

"Unpleasant" is not a strong enough word to describe today's forecast conditions. As the ridge is flattened and pushed eastward, low-level flow becomes more westerly, increasing 850mb temperatures by 2-4C. High temperatures in the upper 90s and dew points in the mid- to upper 70s will combine to create widespread heat indices of 105-110 degrees, likely with some localized spots in excess of 110 degrees. Soundings continue to suggest that afternoon mixing should help to combat rising dew points, but Sunday afternoon obs recorded upper 70s dew points in some locations during peak mixing, and winds will be similarly light today to Sunday, so the mixing that occurs will likely not be strong enough to be effective at limiting dew points very much. As such, Heat Advisory remains in place areawide from 1PM to 9PM this afternoon. Heat Risk guidance depicts widespread Major (Level 3 of 4) Heat Risk, suggesting impacts to anyone without effective cooling or adequate hydration. Efforts should be made to stay indoors whenever possible.

Little relief is expected during the overnight hours, with tonight's low temperatures only dropping into the upper 70s and low 80s. As such, minimum heat indices will drop to upper 70s in much of the area, but the urban heat island in Kansas City will keep the minimum apparent temperature in the low 80s overnight. The much-anticipated cold front looks to arrive so late Monday night that it's better described as Tuesday morning, with areas south of Interstate 70 unlikely to see frontal passage until after peak heating on Tuesday afternoon. For this reason, kept the segment of the Heat Advisory that continues until 7PM on Tuesday confined to these areas south of I-70, where another day of 100-105+ degree heat indices are expected.

Storm Chances Late Tonight/Tuesday Morning:

Convection is expected to fire in Iowa late this afternoon into this evening, initially as discrete cells and then forming into multicell clusters. In the early hours of Tuesday morning, most CAM guidance depicts storms becoming widespread and forming into a line along the front in north-central and northeast Missouri, with coverage becoming increasingly scattered/less organized along the front as you get further west. Depending where the prefrontal convection forms and develops to our north, there is a scenario where we could see some storm leftovers move into the area ahead of the actual cold frontal passage, which would lead to multiple rounds of storms and an earlier precip onset time. However, this is the least likely potential scenario, with most CAM guidance depicting similar locations and timing windows for showers and storms, and primarily keeping the most widespread storms to the east of most of our area.

As the upper-level jet streak begins to move into the Midwest Monday night into Tuesday, shear profiles begin to improve, with 30-40kts of shear by 00Z Tuesday and continuing to increase through the overnight hours. Instability will be best (3000J/kg+ MUCAPE) during the evening hours and along the front to our north, but wanes quickly after 1AM Tuesday, which is when the window for the arrival of the front opens up. Due to the unfavorable overlap of severe ingredients, the widespread severe weather risk for most of the area should be limited, but we will have to monitor for potential severe winds with any clusters that develop to our north and move into the area overnight. Areas along and north of a Unionville to Kirksville MO line are currently in an SPC Slight (Level 2 of 5) Risk for severe storms, with a very narrow Marginal (Level 1 of 5) Risk bracketing its southern edge.

Smoke/Haze:

As the stationary front begins to lift back northeast this morning as a warm front, the smoke in north-central and northeast Missouri should get mixed out and clear by the afternoon. However, northwesterly mid-level winds behind the front on Tuesday will slowly begin to advect smoke from wildfires in Canada back into the area by late Tuesday afternoon into Wednesday, potentially causing a few days of air quality concerns for sensitive groups as the smoke mixes down to the surface. Additionally as a result, Tuesday and Wednesday should have some colorful sunsets.

Midweek Into The Weekend:

Wednesday and Thursday's temperatures will be much more pleasant behind the cold front, with highs in the upper 70s and mid-80s and much drier air. As the ridge continues to slowly be smushed and pushed east through the week, most models indicate several vort maxes traveling along its northern periphery. These vort maxes appear likely to cause a couple of nocturnal MCSs across the Northern Plains later in the week. Wednesday night will likely be the first system we see, with 30-50% PoPs confined to areas along and west of the Highway 65 corridor (likely to be leftovers from a system that is more impactful for areas to our west). Thursday night brings widespread 40-70% rain chances, with Thursday night into Friday morning being our best chance for a widespread wetting rain through the forecast period.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1149 AM CDT Mon Jul 20 2026

Clear conditions are expected to persist through the evening tonight with FEW high clouds building in ahead of a cold front from the north later tonight/early Tuesday morning. Winds are expected to turn out of the north following the passage of this front between 09Z-13Z Tuesday with some high clouds lingering into the late morning.

EAX WATCHES/WARNINGS/ADVISORIES

MO...Heat Advisory until 9 PM CDT this evening for MOZ001>008- 011>017-020>025-028>033-037>039. Heat Advisory until 7 PM CDT Tuesday for MOZ040-043>046-053- 054. KS...Heat Advisory until 9 PM CDT this evening for KSZ025-102>105. Heat Advisory until 7 PM CDT Tuesday for KSZ057-060.