textproduct: Omaha/Valley

KEY MESSAGES

- Scattered showers and storms continue overnight, mainly across northeast Nebraska. A strong storm cannot be ruled out.

- Highs climb into the mid to upper 90s Tuesday before a cold front brings showers and storms. A few strong storms are possible, with hail, damaging winds, and heavy rainfall the main hazards.

- Cooler weather returns Wednesday and Thursday, with highs in the upper 70s to mid 80s. Rain chances return this weekend, followed by another cool-down early next week.

DISCUSSION

Issued at 1018 PM CDT Mon Sep 7 2026

Tonight and Tuesday...

Water vapor imagery and objective analysis late this evening depicts a mid-level ridge centered over the southern and central Plains while a deepening cut-off low tracks eastward across Montana/Alberta. A weak surface front draped from central Nebraska into southeastern South Dakota has served as a focus for thunderstorm development earlier this evening. A modestly unstable airmass with steep mid-level lapse rates is in place over northeast Nebraska, though deep-layer shear remains rather limited (around 25 kts). However, a 35-40 kt LLJ in place has allowed for some hodograph curvature and enough low-level shear for initial storm organization with a supercell that tracked over northeast Nebraska into southeast South Dakota before growing into more of a messy, upscale cluster. With this in mind, a strong storm or two swiping across northeast Nebraska can't be ruled out, though that chance will decrease through the overnight period as stability increases. Scattered showers and storm will persist and slowly sag southward into Tuesday morning as low-level moisture transport and WAA continues to point into the area.

Tuesday, the aforementioned northern low will push a northeast-to- southwest oriented trailing cold front into the area. High temperatures will depend on how far south the front progresses before peak daytime heating. High temperatures are expected to reach the mid to upper 90s across southeast NE and southwest IA. Continued low- level moisture transport ahead of the front will bring dewpoints into the low to mid 70s, pushing heat index values into the 104-108 degree range, generally along and south of Interstate-80 where a Heat Advisory is in place. Further north, highs are expected to peak in the mid 80s thanks to the passing front and continued showers/cloud cover.

Storm chances increase along the slowly advancing front Tuesday afternoon and evening as it passes through an increasing unstable airmass. While large scale forcing for ascent remains rather weak, there should be enough convergence along the front for convective initiation. Shear will be the limiting factor, with around 20-25 kts of bulk shear, limiting overall storm organization. Model soundings indicate fairly dry low-levels and DCAPE values approaching 1000 J/kg, which could help to promote severe weather gusts (60-70 mph) with any storms that quickly pulse up and collapse. Pocket of hail (up to 1.50") also can't be ruled out given the modestly steep low-level lapse rates in place. Into the evening and overnight period, attention will shift to heavy rainfall as training storms persist behind the front, generally along and south of I-80, brining repeated rounds of rainfall. Storms will be efficient rain producers, with PWAT values approaching 2 inches (near the daily maximum of sounding climatology) and warm cloud depths of 4-4.5 km. CAM guidance suggests pockets of 2-3+" before showers gradually taper off from north to south through Wednesday morning.

Wednesday and Beyond...

The passing disturbance to the north will help to dampen the ridge that has dominated the region with above-average temperatures through the beginning of September. As a result, zonal flow will return to the area and drop highs on Wednesday and Thursday into the upper 70s to low 80s. On Friday, a brief mid-level ridge will pull a warm front northward across the area and allow highs to climb back into the mid to upper 80s. The warmer temperatures won't last long, as a passing disturbance will push a cold front back across the area into Saturday, dropping highs into the upper 70s to mid 80s, while also bringing PoPs of 40-60%.

Looking further ahead, long-range guidance is coming into consensus on bringing a mid-level low across the northern Plains late next weekend into the early work week. This system is expected to bring another round of 30-50% PoPs as well as a push of CAA into the region, dropping high temperatures into the 70s for most locations, with a few spots potentially peaking in the upper 60s Monday and Tuesday. For reference, the last time Omaha's high temperature peaked below 70 degrees was May 21st.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 534 AM CDT Tue Sep 8 2026

Have tweaked the timing of expected afternoon/evening thunderstorms by pushing them earlier a few hours at KOMA and KLNK. There's still uncertainty and I expect further adjustments on timing and placement. Some storms will be severe.

Morning showers at KOFK should remain lightning free and wrap up by 8am before redeveloping around 3:00 PM.

Winds out of the south this morning, will be replaced by northerly winds over the course of the day as a cold front sags from northwest to the southeast.

OAX WATCHES/WARNINGS/ADVISORIES

NE...Heat Advisory from 1 PM this afternoon to 7 PM CDT this evening for NEZ066>068-078-088>093. IA...Heat Advisory from 1 PM this afternoon to 7 PM CDT this evening for IAZ079-080-090-091.