textproduct: Topeka

KEY MESSAGES

-Cold front moves through this morning, bringing cooler conditions for mid-week.

-Rain chances increase for the last half of the week, with the potential for heavy rainfall increasing Thursday night.

-Heat and humidity build back in this weekend.

DISCUSSION

Issued at 223 AM CDT Tue Jul 21 2026

A cold front is moving through northern KS very early this morning, shifting winds to the north-northeast. The front should be near I-70 by 09Z and completely through the CWA by 13Z. The air mass immediately behind the front is slightly cooler and drier. Temperatures today will be about ten degrees cooler in northern KS compared to yesterday, but only about two to five degrees cooler near and south of I-70. The more significant difference will likely be the lower dew points as the boundary layer mixes drier air down this afternoon. Some CAMs, like the HRRR and RAP, are more aggressive with mixing, which results in higher ambient temps. However, the official forecast sides more with HREF values. Given the slightly lower T/Td forecast, we were able to cancel the advisory for Coffey and Anderson Counties for today. While advisory criteria is not expected, heat index values could still approach 100 degrees in those locations. A few CAMs also show isolated showers moving out of southern Nebraska mid-morning. Have kept POPs less than 10 percent for now.

Noticeably cooler air arrives area-wide Wednesday as a surface ridge becomes more established over the area. Highs will reach the mid to upper 80s with afternoon dew points mainly in the upper 50s. Precipitation chances also return to the forecast on Wednesday, mainly for north-central and far northern KS initially. More widespread POPs increase Wednesday night and Thursday morning on the nose of a LLJ and in a zone of isentropic ascent ahead of an approach mid-level shortwave trough.

Another round of rain is then likely (70-80% chance) Thursday night and early Friday when the aforementioned mid-level wave moves over the area. Another LLJ will bring deeper moisture into northeast KS. Models seem to agree on pwats near 2.0 inches with at least minor amounts of elevated instability. This is leading to concerns for heavy rainfall during this timeframe. NBM has a 60 percent chance for at least one inch of rain at KTOP and about a 35 percent chance for at least two inches. Excessive rainfall could lead to isolated flooding.

Dry weather then return to the forecast this weekend when an upper ridge build back in from the southwestern US. Heat returns as well with temperatures back to the 90s on Sunday. Heat index values could again approach advisory criteria at that time.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 604 AM CDT Tue Jul 21 2026

North-northeast winds increase to around 10 kts this morning behind a boundary that moved through overnight. Winds turn light this evening. VFR continues with just periodic scattered mid-level clouds this period. Atmospheric smoke also looks to move over the area today, however, am currently not expecting reduced sfc visibility.

TOP WATCHES/WARNINGS/ADVISORIES

None.