textproduct: Topeka

KEY MESSAGES

- Flood Watch has been issued for parts of northeast KS this evening and overnight. Uncertainty exists in how much rainfall will come this far south, but the watch area already has well saturated ground from last night's rainfall.

- Additional storms are expected late Saturday night through Sunday. Locally heavy rainfall and flooding are again the main concerns.

- A hot and humid pattern takes shape next week, with forecast heat indices around 105 degrees for a few days in the middle of the week.

DISCUSSION

Issued at 303 PM CDT Fri Jun 5 2026

Water vapor imagery early this afternoon shows the area within quasi- zonal flow aloft with a closed low upstream coming out of Mexico and into west Texas. Sfc obs show an area of low pressure in the High Plains of CO with a washed out boundary from the inverted trough extending across southeastern NE. Visible satellite imagery has a better depiction of the boundary, which looks to be placed in a west- east oriented line between Lincoln and Beatrice. There isn't much upper forcing to trigger convection, but enough sfc convergence looks to develop storms along the boundary in southeastern NE this evening. Much of the 12z CAM guidance keeps this activity north of the state line through tonight and the HRRR has been consistent in that trend as well. However, a couple of the solutions have storms grazing our area for a short time period. This would be within the realm of possibility if the storms to our north can develop enough of a cold pool to generate some additional storms downstream. It should be noted that moisture pooling along the boundary should result in an axis of plentiful instability (4000-5000 J/kg of CAPE) with marginal shear (25-30 kts). This could support a few severe storms if they can make it far enough south.

The bigger concern, however, is the heavy rainfall and flooding threat. Pwat values still look to be around 1.5" in far northeast KS this evening with HREF showing 90th percentile QPF amounts as high as another 1-2" in the same areas that received 5-9" of rain last night into early this morning. Even the 75th percentile shows 0.5 to 1" of rain in this area, which could still be enough to exacerbate ongoing flooding issues. Brown County in particular has very low flash flood guidance. So despite confidence in occurrence of storms being lower than normal for issuing a flood watch, decided that this high-end potential combined with antecedent conditions was enough to be prudent and issue the watch.

Most of the daytime hours Saturday look dry, although a few of the CAMs are showing isolated convection in our area during the afternoon, to the north of the system lifting out of TX. Unfortunately those isolated cells could once again impact areas that are already saturated. Still, the better rain chances come as the system to our south lifts north across the area late Saturday night and especially through Sunday. Highest confidence in widespread rain looks to be across eastern KS, where Pwat approaches record values.

That trough axis pushes east Monday morning and should end this round of rainfall. Some models are hinting at another subtle shortwave rounding the northern periphery of the ridge Monday afternoon/evening, which could result in another round of rainfall, but there are some differences in where that perturbation ends up, leading to less confidence in our area being affected by heavy rainfall. From there, upper ridging takes hold into the middle of next week, leading to hot and humid conditions. Heat headlines may be needed as head index values are forecast to be around 105 degrees.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1231 PM CDT Fri Jun 5 2026

Stratus from this morning has scattered out, leaving behind some cumulus early this afternoon around 2-3kft. Otherwise, expect SSW winds to gust near 20 kts at times through around sunset before diminishing this evening. Will be monitoring for additional TS development north of the KS/NE border, and currently think any convection should stay north of terminals tonight. Cloud cover may increase a bit towards the end of the period.

TOP WATCHES/WARNINGS/ADVISORIES

Flood Watch from 7 PM CDT this evening through Saturday morning for KSZ010-KSZ011-KSZ012-KSZ024.