textproduct: Omaha/Valley

KEY MESSAGES

- A Heat Advisory is in effect for northeast Nebraska Sunday and the entire area Monday. Expect heat index values in the 100 to 110 range in the afternoon. Overnight heat indices will remain in the mid 70s, providing little relief.

- There are spotty storm chances Sunday afternoon, late Sunday night, and Monday afternoon/evening. Chances remain in the 10-20% range, but if storms develop, a few could be strong to severe, especially Sunday night and Monday afternoon.

- Cooler weather returns by midweek, with high temperatures falling back into the 80s. Along with more seasonable temperatures, there will be increasing chances for showers and thunderstorms Wednesday night into early Friday.

DISCUSSION

Issued at 1146 PM CDT Sat Jul 18 2026

Evening analysis showed surface cold front along the IA/MO border into central NE and northwestward toward the NE/WY/SD border area, more as a stationary/warm front. This feature will push eastward overnight and through the day Sunday, reaching the NE/IA border toward early to mid-afternoon. Several pieces of guidance hint at some fog development in vicinity of that boundary overnight. In addition, model soundings only show a very shallow layer of stronger winds aloft, so wouldn't rule out at least some patchy development elsewhere, especially with dewpoints hanging in the lower to mid 70s as of 10 PM and low temperatures expected to be similar to those values. Another feature of note this evening was some weak shortwave energy sliding through northeastern WY. This will lead to some shower and storm development across SD, some of which may be approaching the forecast area Sunday morning. Latest guidance is in pretty good agreement that they die off prior to getting here, but with the boundary in the area, there are some signs of redevelopment in vicinity of that boundary by the afternoon as the shortwave continues diving southeast. Once again, not expecting any severe weather, but can't rule out some gusty winds or small hail. Otherwise, the main weather of note on Sunday will be the hot and humid airmass, with highs in the lower to mid 90s for most, and near 100 near the NE/SD border. Heat indices will top out near 100 for most of the area, with portions of northeast NE hitting 105, where a Heat Advisory will be in effect. Of course, any precip could significantly impact temperatures in a few areas if it does develop.

Attention then turns to Sunday night as some additional shortwave energy pushes into SD, co-located with the nose of some low-level moisture transport. Additional showers and storms are expected to develop and track east/southeast, potentially producing some strong to damaging winds. Still quite a bit of spread on track of these storms, with some guidance (19.00Z HRRR) suggesting portions of northeast NE and west-central IA could get clipped by some dissipating, but still strong or maybe even severe storms after midnight. That said, a vast majority of other guidance keeps them off to our northeast, so giving it about a 10% chance we see anything. It'll seemingly come down to where the primary CAPE gradient/axis sets up.

Even warmer air will build in for Monday with NAEFS and EPS mean 850 mb temperatures around 25-28+ C, good for the 90th-99th percentile of climatology for this time of year. Mixing that down would easily give us high temperatures in the 100s, but given guidance's propensity to overshoot temperatures and under- do dewpoints the last several days, adjusted the forecast in that direction. Still, looking at highs in the mid 90s to lower 100s with heat indices of 100 to locally 110. As a result, expanded the Heat Advisory on Monday to cover the entire forecast area.

By Monday afternoon/evening a cold front will start pushing in from the north and should bring us some additional showers and storms, with guidance suggesting we'll have at least a little shear to keep storms organized. In addition, given the hot and humid airmass, we'll have plenty of instability to work with. So we'll have potential for some strong to severe storms as the front works through the area, with SPC currently highlighting a level 1 of 5 (marginal) risk for portions of the area. For what it's worth, various machine learning severe weather guidance has trended severe weather probabilities up for our area. Definitely a timeframe to keep an eye on though, especially if you have outdoor plans.

Behind the front and with the primary ridge axis being pushed to our west, we'll finally see some relief from the heat, with high temperatures falling into the 80s and lower 90s through the remainder of the work week. We'll also see increasing shower and storm chances as a couple shortwaves push through Wednesday night/Thursday and Thursday night/Friday (40-60% chance for both timeframes). Machine learning severe weather guidance continues to suggest our potential for severe weather with these chances will remain quite low.

For next weekend, signs are pointing toward upper level ridging and warmer air returning, with widespread highs in the 90s and latest guidance suggesting at least a 30-50% chance of exceeding 95 degrees.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1205 PM CDT Sun Jul 19 2026

VFR conditions are expected through the TAF period. Light southeast winds continue this afternoon with a few clouds around FL060. Afternoon showers and thunderstorms are possible along a weak front draped across far eastern Nebraska. At this time the threat is low (20% chance). Trends will be closely monitored if an isolated thunderstorm does develop and cause aviation impacts, mainly at OMA. Winds will gradually shift towards the south and eventually southwest tonight through Monday afternoon ahead of an approaching weather system.

OAX WATCHES/WARNINGS/ADVISORIES

NE...Heat Advisory from 10 AM to 10 PM CDT Monday for NEZ015-018- 030>034-042>045-050>053-065>068-078-088>093. Heat Advisory until 10 PM CDT Monday for NEZ011-012-016-017. IA...Heat Advisory from 10 AM to 10 PM CDT Monday for IAZ043-055- 056-069-079-080-090-091.