textproduct: Topeka

KEY MESSAGES

- Multiple rounds of heavy rain, beginning Tuesday PM and ending Thursday night. Flood Watch remains in effect for parts of north- central and northeast Kansas.

- Widespread rainfall totals of 1-3" are expected. Locally higher amounts of around 5".

- A few stronger storms are also possible Wednesday evening towards central KS, with gusty winds the main hazard.

DISCUSSION

Issued at 319 AM CDT Tue Sep 29 2026

An impressive look on water vapor imagery this morning, with a deep upper low over southern California beginning to absorb Hurricane Polo as it makes landfall over Baja California. Broad southwesterly flow is in place ahead of the low all the way eastward to the Plains, allowing tropical moisture to stream northwards. Yesterday evening's 0z sounding here at TOP had a PWAT of 1.27" - most guidance takes that all the way up to around 2.0" by tonight's 0z sounding. This will set the stage for multiple rounds of heavy rain as the upper low approaches the Plains over the next couple days. The first round arrives this afternoon and evening as a weaker lead wave approaches the Plains. While most of the area should see some rain with this first round, the most widespread rain and best potential for local 1-3" totals by tomorrow morning should be across north-central KS.

After perhaps a bit of a lull Wednesday morning, the focus will remain across north-central KS for the next round of showers and storms. Mid-level dry slot nosing in across western KS should help an axis of instability develop across western/central KS, though the extent of this will depend on coverage of earlier clouds and rain. At any rate, expecting another round of convection to develop towards central KS during the afternoon and evening. If around 1000 J/kg of CAPE can develop just west of the area, it's not out of the question for a few stronger storms with isolated damaging winds. The heavy rain will remain the main hazard though. Good confidence in some more pockets of 1-3" towards north-central KS, given deep moisture, weak instability, and strong synoptic forcing.

Wednesday night may see another brief lull in rain coverage before more widespread rain redevelops early Thursday. This will be as the best mid-level height falls overspread the area with the approach of the upper low and a cold front begins to shift southeast across the area. In contrast with the first two rounds, which should see less of an impact across east-central KS, this last round will see heavy rain potential across the entire area through Thursday evening.

While the recent trends in model guidance have actually been a slight shift back to the south, the total QPF forecast (Tuesday through Thursday night) remains a general 1-3" across a majority of the area. The greatest potential for local amounts to around 5" still appears to be across north-central and northeast KS where the Flood Watch remains in effect, as this area is most at risk for multiple rounds of heavy rain.

Rain chances will drop off in the wake of the cold front, with just a few leftover light showers by Friday morning. In contrast to the highs in the 80s today and tomorrow, highs Friday through Sunday behind the front look to stay in the 60s to low 70s. A drier airmass and clearing skies should help overnight lows drop into the 50s.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 549 AM CDT Tue Sep 29 2026

Winds become more southerly and pick up to around 10-12 kts by mid-day. The main challenge will be timing multiple rounds of showers, and any potential lower ceilings with them. Currently expecting one more scattered round to move northeast over the late afternoon to mid evening hours, followed by a second round of likely greater coverage farther west towards KMHK overnight. Some guidance suggests these showers will be accompanied by MVFR to IFR stratus, but past similar setups suggest that these lower ceilings will be more scattered, with low-end VFR ceilings generally prevailing.

TOP WATCHES/WARNINGS/ADVISORIES

Flood Watch from this evening through Thursday afternoon for KSZ008- KSZ009-KSZ010-KSZ011-KSZ012-KSZ020-KSZ021-KSZ022-KSZ023-KSZ024- KSZ034.