textproduct: Topeka

KEY MESSAGES

- Patchy fog this morning, then dry weather with near average temperatures is forecast for today.

- There is a slight risk for severe thunderstorms Tuesday evening/night, but much uncertainty exists with this setup.

- Another chance of showers and storms (30-50%) comes late Wednesday night into Thursday morning.

- Temperatures may trend slightly warmer into next weekend, but look to remain near seasonal norms.

DISCUSSION

Issued at 441 AM CDT Mon Aug 17 2026

The forecast area is on the southern edge of the main westerlies aloft, which cover the northern tier of the CONUS while the ridge has been pushed just to our south. A convectively induced vort max near the OK panhandle is on track to keep that batch of storms in southern KS this morning. Surface high pressure is now in control over the Central Plains, and the combination of light winds, clear skies, and cooling below crossover temperatures has allowed for some patchy fog to form. Soundings show this shallow fog should mix out an hour or so after sunrise, but in the meantime, be on the lookout for quick reductions in visibility in low-lying areas.

The rest of today looks dry with partly cloudy skies and highs in the 80s. One thing to watch towards the evening hours will be a shortwave ejecting out of the Northern Rockies into the High Plains that is progged to spark some convection in western Nebraska. Given the position of the LLJ, it would make sense that any convection that sustains itself overnight would stay in Nebraska, which is what most CAMs have shown. The 00z HRRR appears to be an outlier in bringing more scattered convection into our area overnight, but it's worth monitoring to ensure that is indeed the case. Most CAMs track the storms through the MO River Valley overnight, which may end up clipping northern KS Tuesday morning mainly around the Hwy 36 corridor.

The aforementioned convection Tuesday morning is the first factor that complicates the forecast for the rest of Tuesday, which looks to be based on mesoscale processes difficult to ascertain at this time range. If enough rain and cloud cover linger far enough south, that could keep temperatures cooler than forecast and also have an effect on how much destabilization occurs. That convection could also leave an outflow boundary that may or may not be the focus for developing storms later. Interestingly, the 06z short-term guidance has trended further south with the sfc low pressure in western KS, which keeps the warm front further south (consensus would have it around the KS River Valley). This then brings the cold front through the area faster with storms potentially further south than previous runs had as well. Regardless of which side of the warm front you look at, forecast soundings show a lot of CIN with a surface-based or mixed-layer parcel, so it would seem to be tough to get a storm going until the cold front comes through and triggers elevated storms, which is what the CAMs seem to be showing. While deep-layer shear is sufficient for supercells, am skeptical as to how much of that will be realized given that issue. Still, if a strong enough updraft develops, can't rule out some storms producing damaging winds or small hail. All this to say, there is decent confidence in storms forming, but what is uncertain is the timing and intensity of them. They should move out during the overnight hours.

By Wednesday, cooler temperatures are once again forecast behind the front with highs back in the 80s. Northwest flow develops aloft with a large trough encompassing eastern Canada into the Great Lakes region. Another embedded perturbation aloft looks to trigger another round of thunderstorms Wednesday evening into early Thursday morning, but uncertainty in the timing and placement of that wave keeps PoPs limited to 30-50% for now. The rest of the week into next weekend sees the upper ridge building to our west, which favors at least a slight warming trend. Cluster analysis shows good agreement on that ridge, but it does show differing ideas on how well amplified the Great Lakes trough will still be by the weekend. That could have an effect on how much we will actually warm up if we keep more easterly winds in the low levels. So while highs are forecast to be a bit warmer next weekend than the middle of this week, they are generally still close to average, and a small warmup seems reasonable at this time.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 622 AM CDT Mon Aug 17 2026

Shallow ground fog could result in some brief vis reductions to MVFR or IFR for the early part of this morning. That should burn off by 13-14z with light and variable winds the rest of the period.

TOP WATCHES/WARNINGS/ADVISORIES

None.