textproduct: Topeka

KEY MESSAGES

- Periods of rain continue through Thursday, which could be heavy at times. An additional 1.5 to 3" are forecast with locally higher amounts around 4" possible, which leads to increased flooding concerns for areas that saw the most rain last night.

- A few severe storms are possible this afternoon and evening, mainly west of Hwy 75. These may produce damaging winds or a tornado or two.

- Dry weather returns for the weekend into early next week with highs in the 60s and 70s.

DISCUSSION

Issued at 253 PM CDT Wed Sep 30 2026

Upper low continues to spin over the Four Corners region while the main westerlies are along the US-Canada border. The sfc low has been slowly moving through the OK/TX panhandles into southwest KS early this afternoon. Strong synoptic lift driven by WAA and divergence aloft has brought a broad area of continuous light rain with pockets of moderate to heavy rain at times this morning and afternoon, all within an environment comprised of Pwat around 2" with the moisture axis overhead. Today's rain has mostly impacted central and parts of northeast KS, much of the same areas that saw the heaviest rainfall last night. Washington, Marshall, and Nemaha Counties had a swath of 2-3" last night into this morning with light rain lingering into this afternoon, so this area would be the most primed for flooding issues with any additional heavy rainfall between now and Thursday.

The warm front has washed out with the ongoing rain and is not well- defined. Our sfc winds are mainly southerly, but are backed to the southeast towards central KS (closer to the center of the low). Visible satellite shows the dry slot working its way through southwest KS, and the thinking is once that arrives into central KS, that should allow for better destabilization with SBCAPE between 500- 1000 J/kg. It remains questionable how much time the atmosphere will have to become unstable enough to develop severe storms in our area, but the increasing LLJ late this afternoon into early evening will only help low-level shear profiles. With veering winds, 0-3km shear around 40 kts and 0-3km SRH around 200 m2/s2, it may not take as much instability as one would expect to get a strong enough storm to produce a quick tornado or two. The window of opportunity looks rather short, especially as our area would be on the eastern fringes of the threat and would take longer to see enough clearing, but will need to look out for this potential particularly between 4-8pm today.

Outside of the severe risk, heavy rain and flooding remains the biggest threat especially for those areas that already received heavy rain as mentioned earlier. It wouldn't take much additional rainfall for the northernmost counties in the watch to exacerbate flooding issues or lead to more flooding. Once the bulk of the rain this evening moves north and east of the area, there should be a more notable break overnight, although a few scattered showers are still possible along the KS/NE border. Closer to daybreak Thursday, another surge pushes north out of OK into east central KS and coverage also increases along the cold front stretched across northern KS. This front will gradually move west to east across the area throughout the day, leading to wet weather area-wide. The heaviest rain should come to an end in northern KS during the afternoon, while east central KS should see continued rain into the early evening, becoming lighter later into the night. A general 1.5 to 3" with locally higher amounts around 4" should be expected on top of what has already fallen. Some of this is in locations outside of the watch, with the 12z HREF showing some high-end potential for 3-4" south of I-35. However, this area is not nearly as saturated as those further north, so opted to leave the Flood Watch as is.

The upper system weakens into Friday with the front passing east, leading to a transition to zonal and eventually northwest flow aloft. Several days of dry weather are expected, a welcome change to help us dry out after the wet weather this week. Temperatures will be coolest on Friday immediately behind the boundary with highs in the 60s followed by lows in the 40s Saturday morning. We then warm slightly with highs in the 70s and lows in the 50s the rest of the forecast period.

AVIATION /00Z TAFS THROUGH 00Z Friday/

Issued at 619 PM CDT Wed Sep 30 2026

Initial line of showers and thunderstorms will continue to impact KTOP and KFOE through 04Z. Best chance of TSRA remains until 02Z, so kept the PROB30 through 02Z. Low clouds will hang around overnight, but there should be a break in rain until the 13-14Z timeframe Thursday morning. Conditions will certainly drop to MVFR at KTOP and KFOE and stay MVFR to IFR at KMHK this evening due to low clouds. Clouds may lower to IFR at KTOP and KFOE around 09Z, but kept ceilings low MVFR at this time. There may be some drizzle overnight, but main driver of restrictions will be low ceilings overnight. Thunderstorms return Thursday afternoon and will bring heavy rain if they move directly over the terminals. For now kept the threat of TSRA as PROB30 groups and the timing may need to be adjusted as the axis of heavy rain and thunderstorms will depend on how this highly complex weather system evolves over time.

Wind will remain predominantly southerly overnight shifting more northerly Thursday morning. Wind will generally remain light, less than 10 knots, overnight through Thursday morning. As the weather system shifts south and east Thursday afternoon a boundary should shift south bringing a shift in wind from the northeast. This northeast wind will be breezy with sustained wind between 10-15 knots and gusts around 20 knots through Thursday afternoon.

TOP WATCHES/WARNINGS/ADVISORIES

Flood Watch through Thursday afternoon for KSZ008-KSZ009-KSZ010- KSZ011-KSZ012-KSZ020-KSZ021-KSZ022-KSZ023-KSZ024-KSZ026-KSZ034- KSZ035-KSZ036-KSZ037-KSZ038-KSZ039.