textproduct: Topeka

KEY MESSAGES

- Scattered showers or storms this afternoon and evening and again on Sunday

- Heating up Sunday and Monday. Heat index values around 105 degrees are forecast Monday afternoon.

- A slight cooldown is expected by the middle of next week, along with chances for showers and storms Wednesday night through Friday.

DISCUSSION

Issued at 204 PM CDT Sat Jul 18 2026

The synoptic pattern remains stagnant across the region this afternoon with broad mid-level ridging stretching from the western CONUS into the Plains and an upper low over the TX/OK panhandles. Another typical hot and humid summer day has evolved with temperatures in the 90s and heat index values approaching 100 degrees. While forcing is lacking, an uncapped and unstable airmass has again allowed for cumulus to develop, although sustained updrafts have not been observed to this point. Nonetheless, scattered showers and isolated storms could develop this afternoon and evening. Meager lapse rates and weak shear will preclude severe weather, but any storm that does form could produce heavy downpours and gusty winds. There is some signal from CAMs for isolated showers to continue overnight, similar to last night. A lack of forcing and the loss of diurnal heating favors dry conditions, but there remains enough elevated instability for a couple of showers or even of rumble of thunder overnight.

The mid-level ridge expands southeast Sunday and Monday, leading to slightly warmer temperatures over the next couple of days. With little change in the overall airmass, an unstable and uncapped environment will support scattered showers and storms again on Sunday, with at least some potential extending into Monday. Given the potential for precipitation and cloud cover, the NBM has trended a few degrees lower for high temperatures both Sunday and Monday, but it will still be plenty hot with heat index values of 98-102 degrees Sunday and 100-106 degrees Monday. A Heat Advisory may be needed on Monday, especially if it becomes more clear that the daytime hours will be dry.

A cold front is progged to move through the area Monday night into Tuesday morning. Speed of the front and the cooler, drier post- frontal air is varied amongst ensemble members, shown by a 5-8 degree spread in the 25th-75th percentiles for high temperatures on Tuesday. The majority of guidance shows the front through the forecast area by early afternoon, which increases confidence in temperatures being cooler than Monday, but exactly how much cooler remains in question. Guidance also favors a dry frontal passage due to the unfavorable timing and limited deep moisture. That being said, there is a small chance for showers/storms along the front, especially if the front is slower to move through the area. The cooler airmass does spill into the region for the middle of next week; highs are forecast to be near or slightly below normal Wednesday and Thursday. Perturbations moving through the flattened flow leads to increasing precipitation chances Wednesday through Friday, with highest chances (30-55%) coming Wednesday night into Thursday morning.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 608 PM CDT Sat Jul 18 2026

Still VFR conditions outside of a brief shower mainly hanging around the KTOP/KFOE terminals through 01Z but could linger slightly longer. Showers around the KMHK terminal likely remain south but still have PROB30 mention through around sunset. Expect a similar setup tomorrow afternoon with afternoon showers and a possible thunderstorm developing during peak heating. Winds remain light from the SE tomorrow afternoon outside of any outflows from showers or storms. Not adding a PROB30 mention at this time for near the end of the period but will monitor for the 06Z forecast.

TOP WATCHES/WARNINGS/ADVISORIES

None.