textproduct: Omaha/Valley

KEY MESSAGES

- A few showers and non-severe thunderstorms are possible Saturday afternoon.

- Heat builds this weekend, with heat index values reaching 100 to 108 degrees Sunday and Monday. A Heat Advisory is in effect on Sunday across northeast Nebraska and this will likely need to be expanded on Monday.

- Cooler weather returns by midweek, along with increasing chances for showers and thunderstorms Wednesday night into Thursday.

DISCUSSION

Issued at 1035 PM CDT Fri Jul 17 2026

Quiet and warm this evening under upper level ridging with temperatures as of 10 PM still in the mid to upper 80s for many locations, highest near the NE/SD border and in urban areas. A few pieces of guidance hint at fog development overnight into early Saturday, mainly in river valleys and low- lying area. However, model soundings once again show winds aloft will stay up a bit, so it should be pretty patchy if it does develop once again.

The main feature of note this evening was a surface boundary stretching from central MN, across SD, and into far northwest NE. This will sag southward into the area during the day on Saturday with CAMs in pretty good agreement we'll have at least some scattered shower and storm development along it. Little to no shear to work with along the boundary, but given the warm, humid airmass and enhanced moisture pooling along the boundary, could be enough instability for a few stronger storms with small hail and gusty winds from downbursts. However, severe weather is not expected at this time. Otherwise, it'll be hot and humid once again, but think the aforementioned precip and associated clouds will lead to some slightly lower highs, but still expecting mid to upper 90s for most with some heat indices creeping into the lower 100s.

Warmer air aloft will start to push in Sunday and especially Monday with NAEFS and EPS guidance suggesting 850 mb temps reach 22-25 C Sunday and 25-28 C range by Monday. Model soundings show we should have no issues mixing into those warmer temperatures aloft, meaning temperatures may start to approach or exceed 100 on Sunday, and likely exceed it on Monday (50-80% chance at a given spot). One thing to watch for Sunday will be remnant cloud cover in the morning or even some spotty precip in the afternoon with guidance showing some weak shortwave energy and warm air advection nudging into the area at some point during the day. Should this pan out, temperatures may end up needing to be bumped down. Similar story for Monday as a cold front looks to crash into the area at some point, but still some questions on exact timing. For now, keeping the Heat Advisory as-is for northeast NE on Sunday and holding off on any headlines for Monday given the question of cloud cover and precip along the front. I'd give it a 50-70% chance that we'll need another Heat Advisory Monday with the main question being how much of the area to include.

Behind that front, we'll see relief from the heat with highs in the 80s to lower 90s through next week. Precip chances will also be on the increase as the ridge axis sets up to our west and shortwave energy dives through the northwest flow. Right now, our highest chances look to be Wednesday night into Thursday (40-60% chance) and again Thursday night into Friday (30-40% chance). For what it's worth, various machine learning severe weather guidance suggests the potential for severe weather will be low with these chances.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 545 AM CDT Sat Jul 18 2026

VFR conditions are forecast through the next 24 hours, with little to no fog being reported in area observations this morning. A wind shift has already begun pushing through near KOFK, with winds expected to stay light but vary at KOFK, while KOMA/KLNK stay southeasterly this morning before turning increasingly easterly this evening into the overnight hours.

OAX WATCHES/WARNINGS/ADVISORIES

NE...Heat Advisory from 1 PM to 9 PM CDT Sunday for NEZ011-012-016- 017. IA...None.