textproduct: Topeka

KEY MESSAGES

- Rounds of heavy rain continue into Thursday evening. Still expecting widespread rainfall totals of 2-4", with locally higher amounts up to around 6". Flood Watch extended slightly farther south and east.

- A few strong or severe storms possible this afternoon and evening, mainly west of Highway 75. Damaging winds and a tornado or two could occur.

- Drying out for the weekend with temperatures slightly cooler than average.

DISCUSSION

Issued at 240 AM CDT Wed Sep 30 2026

Current water vapor imagery depicts a textbook upper low spinning over Arizona. Very diffluent upper flow is present to the east of the low, supporting the widespread precipitation over the Central/Southern Plains and even into the Southern Rockies. Given the deep southerly flow ahead of the low and the absorption of Hurricane Polo, near record moisture for the time of year is in place across much of the area. TOP's 0z sounding showed 2.05" of PWAT, tied for second highest on record for any sounding after September 25.

Here in northeast KS, our initial round of light to moderate rain continues this morning. Have seen a bit of a recent uptick in rain rates within an area of 850 mb frontogenesis north of I-70. Would not be surprised to see some local 1-2" amounts across this area by mid-morning. While there may be a bit of a lull behind the first round of activity, expecting the widespread rain over southwest KS and the OK/TX Panhandles to lift northeast over the afternoon and evening. Coverage should be greatest farther west towards central KS, closer to a surface low partially tied to the remnants of Polo. Given the very high moisture and stronger synoptic forcing, would not be surprised to see some isolated spots of 3-6" rain in a short period of time across north-central KS. Day 1 ERO from WPC shows a moderate risk of excessive rainfall over portions of north-central KS, which matches thinking here very well.

And while this flood risk is still the main hazard, also becoming increasingly concerned about a short-lived tornado setup late afternoon into the evening. Ahead of the surface low over western KS, the LLJ is forecast to increase to around 40-45 kts by 0-3 UTC tonight. Coupled with veering low- level winds, effective SRH may increase to around 300 m2s2 with 35-40 kts of effective shear. Instability remains the main question given persistent early day clouds, but even modest heating would support an uncapped 500-1000 J/kg of ML CAPE. With the high PWAT and very low LCLs, this may favor the development of several mini-supercells capable of producing gusty winds and a few tornadoes. The environment looks most favorable towards central KS, though some potential could extend as far east as the Highway 75 area. While every day is different, and thermodynamics may have been slightly more favorable yesterday evening, the presence of multiple supercells and tornadoes in a similar setup near Amarillo yesterday gives credence to the potential.

Shifting back to the heavy rain, we may see another brief lull overnight before rain fills back in Thursday morning. This will occur as the weakening upper low moves east across the state and ascent increases along a southeastward moving cold front. So compared to earlier rounds, this round should see more rain across eastern portions of the state, especially by the afternoon and evening. Have seen a bit more of a southeast trend in recent guidance, so have expanded the Flood Watch slightly southeastward. Still expecting a general 2-4" within the watch area, with isolated higher amounts of around 6". Amounts outside of the watch look slightly less, generally 1-3", but some higher amounts can't be ruled out here as well.

Much less to write about after Thursday night, as drier air behind the front and broad northwesterly flow will keep things quieter. Temperatures remain near to slightly below average into early next week. Highs stay mainly in the upper 60s to low 70s, with lows in the 50s to even upper 40s. No notable precipitation chances, allowing us to dry out after these very wet next few days.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1232 PM CDT Wed Sep 30 2026

Rain has been more persistent at MHK and expect that to continue to be the case through the afternoon, whereas further east at TOP/FOE, light rain is only just starting to get near terminals. Confidence in TS still isn't high enough to do any more than PROB30 groups at all sites, although even without convection there could still be periods of moderate to heavy rain that result in IFR vsby, as we've already seen at times. There should be somewhat of a break later tonight and overnight before rain fills back in mid to late morning. Cigs look to become lower in the back half of the period. Was hesitant to go to IFR as early as guidance shows, as it appears to be overdone with lower cigs with current conditions, but there's enough agreement that it seems to be worth a mention for at least part of the morning.

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.