textproduct: Topeka

KEY MESSAGES

-A chance for showers and a few storms this morning. Thunderstorms redevelop this afternoon and evening. Some of the storms may be strong to severe this afternoon and evening.

-Periodic chances for thunderstorms remain in the short-term forecast as a surface boundary meanders north and south in the region.

-Long-range models keep POPs going through the workweek, but confidence in coverage and timing decreases with time.

DISCUSSION

Issued at 204 AM CDT Sat Sep 12 2026

Early this morning a broad upper level trough was moving east across the northern Plains. The southern extend of the upper trough axis extended southward to I-80 in southern NE. An upper level trough was located off the Pacific Northwest coast. A broad upper ridge extended from FL northward across the mid Atlantic States. The H5 ridge axis extended westward across the Gulf into the far southwest US.

The 6Z surface map showed a cold front extending from central MN, southwest across northeast NE, then southwest into northeast CO. Ahead of the cold front there was a line of thunderstorms across east central and south central NE. These storms have formed an OFB that has pushed south of I-80.

Today through Sunday night:

The H5 trough across the northern and central Plains will gradually shift east across the upper Midwest into the Great Lakes States by Sunday night.

The surface front and OFB across southern NE will shift southward through the morning hours and scattered showers and thunderstorms may develop along and north of the boundary. The 6Z Meso analysis shows that most of the CWA has less than 500 J/KG of MUCAPE with 2000 J/KG of MUCAPE located across western KS. In the next 6 hours, the MUCAPE will increase above 1500 J/KG across the north central KS, so a few storms along or north of the OFB may be strong with gusty winds and small hail possible. Most of the CAMs show the stronger thunderstorms across south central NE weakening as they push southeast into the TOP CWA after 3 AM. The NSSL WRF looks to be initialized the best and provides the greater chance for showers thunderstorms early this morning across the CWA. The other CAMs show the the line of showers and thunderstorms weakening with only widely scattered to isolated showers and thunderstorms through the morning hours.

This afternoon the HRRR, 3km NAM, and RRFS forecast the surface front to stall out along I-70 this afternoon. Thunderstorms will develop along the front during the late afternoon hours, and some of these storms may be severe with damaging wind gusts and large hail. Effective shear may increase to 35 to 45 KTS south of I-70 with MLCAPE 1500 to 2500 J/KG during the late afternoon hours. Most CAMs have backed sfc winds along and north of the OFB that will become stationary across the far southern counties of the CWA. Elevated thunderstorms may develop north of the front across the northern counties of the CWA this afternoon. These storms may produced quarter size hail as MUCAPES north of the front will be over 1000 J/KG. Most numerical models/CAMs have the front pushing south of the CWA after 2Z SUN. Any severe thunderstorms will push southeast of the CWA during the early evening hours. There may be some weak isentropic lift for scattered showers and a few elevated thunderstorms to continue through the night

Sunday, the surface front will become stationary across northern OK, so most of the elevated thunderstorms should remain across southern KS. There may be some scattered showers through the day on Sunday. Sunday night there may be a few more elevated thunderstorms as the surface front retreats northward, and isentropic lift increase across the CWA. The H5 trough across the Pacific Northwest will shift east into the central Rockies by 6Z MON.

Monday:

The H5 trough across the central Rockies will lift northeast into the central high Plains. The surface warm front will shift northward across NE into SD. The CWA will be in the warm sector. Look for a hot and humid day with highs in the lower to mid 90s. Heat indices during the afternoon will reach 100 to 105 degrees.

Monday night through Tuesday:

The extended range models are in good agreement with the H5 trough across the central high Plains lifting northeast across the northern Plains on Tuesday. This will cause a surface cold front to push southeast across the CWA. There may be scattered showers and thunderstorms along and northwest of the front. At this time the stronger effective shear and instability will be located north and northeast of the CWA where the better risk for severe thunderstorms will occur across eastern NE and IA. But a few storms across the CWA ahead of the front may be strong to severe on Tuesday with damaging wind gusts and large hail possible.

Tuesday night through Saturday:

The extended range models show the surface front becoming stationary across the CWA through most of the workweek. H5 trough will lift northeast from the southwest US into the Plains. There will be at least a chance for showers and thunderstorms through the work week. By next weekend a stronger cold front may push southeast of the CWA bringing an end to the rain chances. Highs will range from the upper 70s to lower 80s north to the upper 80s to lower 90s southeast. The temperature forecast will be dependent on where the front becomes stationary across the CWA. The stronger front moving southeast across the CWA next Saturday will cool high temperatures into the 70s.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/

Issued at 1238 AM CDT Sat Sep 12 2026

An outflow boundary across southern NE will shift southward along I-70 by 12Z, which may cause a scattered showers and isolated thunderstorms to develop around the terminals from 12Z-17Z SAT. As the outflow boundary shifts south the chances for showers thunderstorms will diminish Saturday afternoon. Winds behind the boundary will switch to the north but remain under 10 KTS after 12Z SAT.

TOP WATCHES/WARNINGS/ADVISORIES

None.