textproduct: Omaha/Valley

KEY MESSAGES

- Two rounds of storms can be expected Monday. The first during the early morning hours with a strong storm or two possible. The second round, in the late afternoon and evening, brings a conditional risk for severe storms capable of producing large hail, damaging winds, heavy rain, and tornadoes.

- Cooler weather and daily chances for showers and storms can be expected through the majority of the week.

DISCUSSION

Issued at 1112 PM CDT Sun Sep 13 2026

Tonight through Monday...

A few spotty showers and sprinkles lingered over the forecast area this evening, with temperatures finally feeling crisp and fall-like, in the upper 50s.

Quiet nighttime skies will be interrupted by a line of convection developing along an elevated boundary early Monday morning, from southeast through northeast Nebraska. While a strong storm or two can't be totally ruled out, weak instability and the elevated nature of the storms will likely limit large hail and strong wind production.

A stout low level jet will help advect warmer air into the region tomorrow afternoon, as morning convection shifts off to the east. Expect scattered showers with a few embedded rumbles of thunder to develop across the forecast area tomorrow afternoon, as a moist unstable airmass builds into the Central Plains. Highs tomorrow afternoon will top out in the 80s, with a few locations reaching the low 90s in far southeast Nebraska. However, this warm-up will be brief, as a cold front approaches from the west Monday afternoon and evening. Out next conditional threat for severe weather will develop ahead of this front, in a fairly impressive environment. Forecast soundings indicate 2000-3000+ J/kg of CAPE, steep lapse rates, 30- 40kts of low and deep layer shear, as well as notable low level turning in hodographs. These would suggest that all severe modes, including tornadoes, would be on the table. That being said, it doesn't look like a slam dunk widespread severe event. Daytime cloud cover could lower temperatures a bit and strengthen the cap. Additionally, if multiple storms do break through the cap and develop along the front at once, they could quickly grow upscale and congeal into more of a blob, as opposed to strong discrete cells. Additionally, strong downbursts could collapse updrafts before the storms can establish a strong mesocyclone, capable of producing large hail, damaging winds, or a tornado. Overall, it appears the main threat for severe potential would be during the first 1-3 hours after convective initiation, when more discrete storms, with robust rotating updrafts would be possible.

Initial potentially destructive storms will quickly push east of the forecast area Monday evening, with more widespread, but less severe convection filling in behind them. Heavy rainfall will be something to keep an eye on throughout the evening and overnight hours. While deep warm cloud layers and high PWATs indicate storms will be efficient rain producers, the overall progressive movement of the storms should help lower flooding risks. That being said, there remains a 25% risk of flash flooding within a Slight Excessive Rainfall Outlook area, highlighting areas along and east of the Missouri River.

Tuesday and Beyond...

Shower and storm chances will continue behind the front overnight and into Tuesday, as the LLJ noses back into the region. The best chance remaining across southeast Nebraska into southwest Iowa. Temperatures will be noticeably cooler Tuesday, as we slip back into the 70s.

Similarly wet and cool conditions will remain in place as the boundary lingers in the region through at least the middle of next week, enhanced by a few shortwave disturbances rippling through the south westerly flow. Abundant moisture training over the same locations this week could potentially raise flooding concerns once again, however, the gradual, drawn out nature of the rainfall should help.

Temps will remain in the 70s through at least Thursday, with slightly warmer conditions expected Friday, as a subtle ridge develops ahead of the next trough and cold front. Long range models continue to hint at daily rain chances through next weekend, with temperatures dipping back below seasonal levels.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1156 PM CDT Sun Sep 13 2026

VFR conditions, southeast winds, and overcast skies at FL060-FL080 start the period. A strong low-level jet develops over the area during the next few hours. This low-level jet is forecast to initiate an arcing band of thunderstorms between 07-09Z. These thunderstorms will quickly lift northeast through morning. In addition, strengthening southeast winds overspread the region with gusts reaching 20-25 kts. The arcing band of thunderstorms is anticipated to reach LNK around 08Z and OFK/OMA near 09Z. These times may shift slightly but model consensus is high on this approximate timing. Thunderstorms will likely reduce visibility to MVFR with brief reductions to IFR possible. Gusty, erratic winds are not currently anticipated with these thunderstorms. Ceilings will lower through the morning, but should remain VFR at all terminals except OFK which is expected to become MVFR. Clouds break and lift as stronger south winds overspread the region by Monday afternoon with peak gusts between 30-35 kts. Additional thunderstorms are expected near 00Z Monday evening. While there is some uncertainty in the exact timing of thunderstorms, widespread thunderstorms and aviation impacts are likely near and after 00Z.

OAX WATCHES/WARNINGS/ADVISORIES

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