textproduct: Omaha/Valley

KEY MESSAGES

- Precipitation chances increase early Sunday morning, and continue through the afternoon. Severe storms look unlikely.

- Monday will be the next best chance for strong to severe storms.

- Expect a cool down heading into Tuesday and beyond with daily chances for showers and storms.

DISCUSSION

Issued at 1113 PM CDT Sat Sep 12 2026

Tonight through Sunday...

A few post-frontal showers and storms fizzled across far southeast Nebraska this evening, as temperatures fell into the upper 50s and low 60s. Overnight, lows will continue to fall into the low 50s and 60s.

A subtle shortwave will ripple through the upper level flow early Sunday morning. Warm moist air will advect back into the region early tomorrow, allowing a line of showers and storms to develop. While a stronger storm or two may be possible, widespread severe storms look unlikely, given the environment characterized by relatively strong deep layer shear, but little to no instability. Forecast soundings depict PWATs up to 1.4", which is in the top 10% for this time of year. Thankfully, less intense updrafts and scattered nature of storms should help mitigate flooding concerns, although a few pockets of heavy rainfall will be possible. Storms should diminish in coverage through the afternoon hours, though clouds will likely linger through the majority of the day. Expect afternoon highs to remain cool, in the lower 70s.

Monday...

Stronger warm air advection ramps up Monday, as a shallow ridge develops ahead of an approaching cold front. Highs on Monday will bump up into the mid 80s to lower 90s, despite the development of scattered showers in the warm/moist airmass.

The previously mentioned cold front will swing through the region late Monday afternoon and evening, sparking off another round of showers and storms. 40-50 kts of 0-6 km shear, and decent instability will allow initial storms to become strong to severe, capable of producing large hail and damaging winds. Additionally, notable turning in low level hodographs suggests a tornado or two won't be out of the question. Heavy rainfall could also lead localized flash flooding, where storms manage to train over the same area.

Storm coverage will increase through the overnight hours, but severe parameters will gradually wane after sunset, as the environment becomes more worked over.

Tuesday and Beyond...

The frontal boundary will linger from western Kansas through southern Iowa through much of the upcoming week, keeping us cool and wet. Multiple rounds of showers and storms can be expected, especially over the southern half of the forecast area. While details will greatly depend on the exact location of the boundary, an occasional strong storm or two may be possible, as is lightly highlighted by Machine Learning probs, especially Tuesday through Wednesday. Overall rainfall amounts will likely be above normal for this time of yea, given the persistent signal through next week. However, the scattered storm mode and drawn out nature of the events should help mitigate overall flooding potential.

Temperatures will remain nice and cool through the upcoming week. Highs will generally top out in the 70s, with overnight lows falling into the 50s and 60s.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1157 PM CDT Sat Sep 12 2026

Light north winds and VFR conditions start the TAF period. A developing weather system is resulting in a gradual increase in cloud cover between FL050 to FL100. As a weather disturbance moves through the region early Sunday morning into the early afternoon, widely scattered showers and thunderstorms are expected to develop. There is uncertainty on the exact timing and location of these showers and thunderstorms. Current forecast model guidance generally has initial development between 09Z to 13Z from LNK to OMA and east. Additional shower and thunderstorm development is forecast late Sunday morning. These should approach OFK around 15Z with downstream impacts possible at OMA and LNK. Any showers and thunderstorms should exit the region to the east during the early afternoon. Amendments to adjust the most likely timeframe and location of thunderstorm activity is likely as confidence increases. Brief visibility reductions are likely with thunderstorms along with a potential broken MVFR cloud deck. East winds and VFR conditions return for the remainder of Sunday once showers and thunderstorms move east of the area.

OAX WATCHES/WARNINGS/ADVISORIES

NE...None. IA...None.