textproduct: Topeka

KEY MESSAGES

-A series of shortwaves will keep rain chances in the forecast at times this week.

-The highest potential for heavy rain is on Thursday.

-A major pattern shift will then bring a consistently hot and humid trend to the area by next week.

DISCUSSION

Issued at 134 PM CDT Tue Jun 23 2026

At midday today, water vapor imagery and H7 analysis showed a shortwave trough axis within the westerly flow aloft over the High Plains of OK/KS/NE. Associated thunderstorm activity was moving southward along the instability gradient through that region, mainly staying west of the TOP CWA. Some of the showery weather may clip portions of north-central KS today, but the more robust and widespread thunderstorm activity will likely remain south and west where lift is enhanced and higher instability exists. Another weak perturbation in the flow and some minor height falls aloft could trigger a few more storms to develop tonight in southwest KS. Current thinking is that storms are again not likely to impact northeast KS tonight or tomorrow given the general lack of forcing mechanism and instability.

A more significant shortwave looks to impact the eastern half of KS on Thursday. Models show a disturbance moving east across the state during the morning. A large complex of storms could develop in a very moist atmosphere consisting of around 500 J/kg of MUCAPE and around 40 kts of 0-6km bulk shear. Forecast pwat values could approach 2.0 inches which is the daily max of climatology. While a few embedded strong updrafts may exist with the larger complex of storms, heavy rain and flooding appear to be the main concern. NBM has an 80% chance for at least one inch of rain near Topeka, a 60% chance for at least two inches, and a nearly 40% chance for three inches near and south of I-70. However, there is still some uncertainty in exactly where in the area the heaviest axis will set up. Once confidence increases, a Flood Watch may be considered. Precipitation could linger across east-central and southeastern portions of the area into Thursday night as a cold front slowly sags southward. Rain should exit by early Friday.

Predictability of any addition shortwaves decreases toward the weekend before the overall pattern shifts and brings a consistently hot and humid pattern, more typical of July/August to the region. Beginning late this weekend, the mid-level pattern becomes more amplified with a longwave trough axis setting up across the western CONUS and a large ridge expanding over the Mississippi River Valley. The ridge then looks to hold over the Ohio River Valley through at least the middle of next week, keeping the main storm track west of the area and allowing summer-time heat and humidity to dominate our forecast.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1214 PM CDT Tue Jun 23 2026

High clouds move over with a storm system to the west and perhaps some diurnal cumulus develops this afternoon. Rain currently looks to stay west of airports, but will monitor radar trends and amend if needed. MVFR CIGs could develop tonight and some patchy fog also looks possible. Timing may need to be tweaked with future updates. Otherwise, VFR should return late this TAF period and winds will remain light.

TOP WATCHES/WARNINGS/ADVISORIES

None.