textproduct: Topeka

KEY MESSAGES

- Another round of showers and storms are expected (60-90%) to lift northeast across the area tonight.

- There is a 30-60% chance for storms to develop Saturday evening. A strong storm or two cannot be ruled out.

- Periods of heavy rain are forecast for Tue through Thur next week, and several inches or rain could lead to a flooding risk.

DISCUSSION

Issued at 213 PM CDT Fri Sep 25 2026

19Z water vapor imagery had the center of an upper ridge over the TX gulf coast as an amplified upper trough moved towards the northern Rockies. A couple low amplitude shortwaves were noted in the southwest flow over the central plains. At the surface, high pressure was located over the Upper Midwest with low pressure along the lee of the Rockies. This pattern has favored continued southeasterly low level flow and moisture transport north.

The initial wave and associated precip is moving east northeast out of eastern KS as another shortwave comes out of west TX. This should bring a lull in precip this afternoon before the next round of showers and storms move though overnight. Mid level lapse rates are progged to remain relatively shallow limiting instability for storms. So the main risk looks to be localized heavy rain as a very moist airmass remains over the plains. Think the storms within the southwesterly flow should remain progressive enough to mitigate a widespread flooding risk.

For Saturday, the question is whether we can clear out and warm up for thunderstorms to redevelop. Mid level lapse rates could steepen across central KS. If temps can warm into the lower 80s, some moderate instability of around 3000 J/kg of MUCAPE could help spark convection in the afternoon. At this time, there is a fair amount of uncertainty whether we will clear out as the RAP tends to hang onto low clouds well into the afternoon. Think the SWODY2 trend of shifting the risk more towards south central KS is reasonable given the chance for clouds to linger and limit destabilization. If things do clear out, marginal bulk shear of 20 to 30KT may limit storm organization to multi-cellular clusters and a wind risk.

Shortwave ridging is progged to redevelop over the central and southern plains for Sunday and Monday with a break from the rain chances. The main question in the forecast is how an upper trough will evolve coming out of the southwestern U.S. next week. 12Z operational solutions seem to be centering around the idea of a cutoff low slowly lifting through the plains mid to late week next week. However the 00Z ensembles were nearly evenly split on a close versus a more phased open solution. So there remains a fair amount of spread in the predictability of this pattern for Tuesday through Friday. Nevertheless the signal for heavy rainfall is seen in the ensembles with the GEFS and ECMWF ensemble indicating PWs will be 2 to 3 standard deviations above normal. The operational GFS progs PWs to be over 2 inches by 12Z Wednesday. This is likely due to the fact the models are absorbing the remnants of Polo into the upper trough and bringing that tropical fetch of moisture into the plains. Most guidance points to Tuesday night through Wednesday night as the best timing for precip, but if the close solution prevails a slower progression to the system with cyclogenesis could occur causing high precip chances to persist through Friday. This leads to the heavy rainfall risk next week. The NBM shows widespread 2 to 4 inches of rain through Thursday. The 12Z GFS and ECMWF suggest 3 to 5 inches are possible by Friday evening. Widespread rains of these magnitudes even spread out over a few days could lead to flooding. So will have to continue to monitor the trends with the storm system for next week. Temperatures look to remain rather seasonal as the mean westerlies remain across the northern tier of the county with no obvious surge of cold air south seen in the operational or ensemble solutions. Think the NBM/WPC forecast looks reasonable through next week. There could be some adjustments to temps depending on how next week's storm system progresses east.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 521 PM CDT Fri Sep 25 2026

VFR at all TAF sites through the TAF period with off and on showers and potential isolated thunderstorms. A brief break in the rain is expected this evening, before another round of scattered showers develops from the southwest and pushes northeast (generally after around 03z). Conditions will improve from west to east tomorrow morning.

TOP WATCHES/WARNINGS/ADVISORIES

None.