textproduct: Topeka

KEY MESSAGES

-Radiational fog likely develops tonight, especially in areas that had recent heavy rainfall.

-A series of surface boundaries will bring rain chances back to the area periodically throughout this forecast period, starting tomorrow night.

-There will be at least a low risk for strong to severe storms on Saturday and again early next week.

DISCUSSION

Issued at 228 PM CDT Thu Sep 10 2026

Rain has cleared to the southeast as higher pressure has built in from the north today. Cloud cover will continue to scatter this afternoon, with sky conditions becoming mainly clear into tonight. Tonight's set up looks favorable for radiational fog development for much of the area due to clear skies, light sfc winds and ground moisture from earlier rainfall. The only possible limiting factor may be a breeze just off the surface, as shown on forecast soundings. Still, confidence is high enough to include areas of fog tonight and early Friday.

The main challenge with this forecast package is then POPs - determining probabilities and timing.

On Friday, the H5 flow becomes more zonal across KS while today's trough axis deepens over MO. A shortwave will pass to our north across SD and into MN during the day. Sunshine and return flow at sfc will allow temps to be a touch warmer, with highs likely reaching the upper 80s. The aforementioned shortwave may then bring a sfc boundary into southern Nebraska Friday night. A few storms could form (20-40% chance) along the boundary and track southeast into northern KS. Elevated instability would allow for thunderstorms, but shear does not organized enough to produce severe storms.

The surface boundary is likely to remain over northern KS on Saturday. There is some uncertainty in whether overnight storms will linger into the daytime hours, but if rain and clouds are able to clear, the environment could become increasingly favorable for strong to severe thunderstorm development during the afternoon or evening. Storms that develop near or just south of the boundary will do so in an environment featuring steep lapse rates and effective shear around 40 kts. Damaging wind gusts and small hail would be the main hazards.

A progressive pattern has the sfc boundary lifting northward into southern Nebraska on Sunday as a warm front. Aloft, the H5 ridge over the south-central US may begin to transition to the east as a strong Pacific Northwest system progresses eastward across the northern CONUS. That would allow flow over the central US to shift from westerly to southwesterly. Theta-e advection will create an unstable air mass, however, a cap and lack of forcing will likely keep conditions dry from Sunday afternoon into midday Monday. While the Pacific Northwest system will remain well north of the area, an associated sfc cold front looks to slide into northern KS by Monday night. Thunderstorm chances again increase Monday night and more so on Tuesday as the boundary interacts with the moist and unstable air mass. Will keep POPs going into Wednesday until subsidence from high pressure begins to limit vertical motion north of the front.

AVIATION /00Z TAFS THROUGH 00Z SATURDAY/

Issued at 623 PM CDT Thu Sep 10 2026

Fog development will impact the terminals overnight tonight, especially at KTOP and KFOE. Confidence increased for more dense fog development at KTOP so dropped VIS a bit further in the early hours of Friday. Fog should begin to mix out around 8-9 AM into MVFR stratus before CIGs slowly clear by late morning and early afternoon. VFR conditions will be expected for the remainder of the period.

TOP WATCHES/WARNINGS/ADVISORIES

None.