textproduct: Topeka

KEY MESSAGES

- Another cool day today under cloudy skies and periods of showers through the early morning.

- Off and on rain chances with a few embedded thunderstorms into this evening and overnight then possibly again Friday night into Saturday then possibly showers briefly on Sunday morning.

- Gradual warming takes place over the weekend into the beginning of next week.

- More chances for precipitation still look possible into the middle part of next week.

DISCUSSION

Issued at 333 AM CDT Thu May 21 2026

Current WV imagery and 00Z RAOB data show that a western CONUS trough has become more established over the past day with an upper low spinning over the northern Rockies along the Canadian border. This sets up a southwest flow regime atop a weak but broad surface ridge which is part of a broader high pressure cell anchored over the Great Lakes region. Deeper moisture resides across the southeastern CONUS into the southern Plains at the current time with stalled frontal zones across the these regions. Ahead of the broad trough within the southwest flow, a plume of moist return has become more established within the H85 to H7 levels associated with weak isentropic ascent generally along the 310K surface. This is helping to keep showers developing from western into central OK into south central Kansas into the CWA. A few embedded lightning strikes continue off and on as well early this morning with very weak elevated instability in place.

With increased theta-e advection and increased isentropic ascent into this evening and overnight, have chances increasing over east- central into northeast KS areas to around 60-80 percent with PW values increasing to around 1.25" which is still high based on climatological sounding data for this time of year. Thus rain should be efficient at times as the upper trough emerges from the Rockies just to the northwest of the area overnight into Friday morning. This will help draw additional Gulf moisture poleward with slightly more instability in forecast soundings developing. Remaining on the southeastern flank of the best forcing and associated mid level flow much more organized into northern Nebraska and the Dakotas, expect shear to remain overall less organized this far south. Thus, can't rule out embedded thunderstorms but expect overall the threat to remain below severe levels. Due to recent moisture across portions of the area, WPC does have mention of a marginal risk for excessive rainfall, but it appears that with the flash flood guidance around 1.50" or higher for the 1hr guidance, that a training or very slow moving storm would need to become established to cause too much in the way of concern for the tonight period.

Another round of showers and generally non-severe storms may setup into Friday night and Saturday morning generally with a less amplified upper flow pattern with a weak open wave passing mainly to the north of the region again. Mostly beneficial rain should result.

Sunday morning, still some weak troughing into the central Plains as the upper flow pattern slows in response to another Pacific trough digging into the western CONUS. Could still see a few light showers and an embedded storm or two into Sunday morning as a result.

Into Memorial Day, the ridging should build ahead of the western trough digging into the western CONUS. This will help bring the temperatures back to the 80s across the area and the holiday on Monday should be dry the entire day at this point.

By the middle part of the upcoming week, the western trough remains firmly in control and finally lift into the northern Rockies with the broader axis slowly becoming negatively tilted while overall de-amplificaiton takes place. This should allow for additional return of Gulf moisture into the region along with instability but the shear may be low and disorganized with the upper trough displaced well to the northwest during this time frame.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 508 AM CDT Thu May 21 2026

No significant changes from the 06Z forecast. Will keep an ENE surface wind in place to begin the period gradually veering to the E through mid morning. Weak ascent above the slowly receding surface ridge remains in place ahead of a trough digging into the western CONUS. Periods of -SHRA with a few embedded storms over central Kansas possible through mid-morning. Right now, looks like potential for more showers and possibly embedded storms increase by this evening. Trends right now point to most likely time frame being around 06Z and after through the end of the period. Also, IFR conditions still trending highest probability over western and southwestern areas so have only gone with IFR mention around KMHK for now.

TOP WATCHES/WARNINGS/ADVISORIES

None.