textproduct: Omaha/Valley

KEY MESSAGES

- Isolated showers and weak thunderstorms are possible this afternoon and 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 to the rest of the area on Monday.

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

DISCUSSION

Issued at 232 PM CDT Fri Jul 17 2026

Tonight through Saturday...

Much of eastern NE and western IA is near or exceeding the convective temperature this afternoon. In fact around 2pm, a lone cell had formed along I-80 near Neola, IA but has since diminished. A scattered cumulus field has also developed across the entire area, but so far there are only a couple locations with any meaningful vertical cloud depth. Development remains possible this afternoon due to strong heating and instability. Effective deep shear is very minimal, but much like yesterday, high precipitable water values and slow cell motion would suggest high rainfall rates for 15-20 minutes with any shower or storms this afternoon. Overall, it does appear like shower activity is more favorable in Kansas and Missouri today.

It's a little more of rinse and repeat on Saturday on the back of strong diurnal heating. The difference tomorrow will be a west-east orientated boundary that drops south across the area throughout the day. This will likely be a focus for convective initiation during the afternoon. Even though most of the convective allowing models show isolated to scattered coverage, you could make the argument that 15-30% of precip might not cut it across far eastern NE and western IA if the past couple days are any indication. Afternoon clouds could keep the temperatures just a bit cooler as well.

Sunday and Monday...

Ridging over the Intermountain West slides a bit farther east for the second half of the weekend and early next week. This will set the stage for even warmer temperatures during this time frame. But before getting into temperatures, now that we are within 48 hours of Sunday, HRRR/NSSL- WRF/RAP all try to bring in convection early in the morning across north central and northeast portions of Nebraska. Precip during the early morning hours on Sunday seem to tied to pronounced WAA at 925-850mb across South Dakota. Activity will try to move east-southeast with time, but the model trend is to diminish activity before arriving in eastern portions of the state. We will need to monitor how any residual cloud cover affects temperatures on Sunday.

As previous discussions have mentioned, a shortwave trough pushing into the Northern Plains is expected to initiate overnight convection late in the day on Sunday, potentially organizing into an MCS overnight. Ensemble guidance has consistently kept most of the activity north and east of the forecast area across SD/IA. 850mb temperatures climb into the mid to upper 20s on Monday, which combined with breezy south/southwest winds, will set the stage for a run at 100 F for many locations across the area. Unless something dramatic changes with the forecast, this will likely be our hottest day of the summer so far. Most locations have topped out in the mid 90s so far this year.

Tuesday through Friday...

A break from the more extreme heat arrives on the heels of a cold front and will remain in place through next week. By Wednesday night into Thursday, we'll find ourselves on the backside of the surface ridge just to the east of the front. This still looks like our best opportunity for precipitation in the next 7 days. We have included rain chances on Friday as well.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 618 PM CDT Fri Jul 17 2026

VFR conditions favored through the period with lingering clouds around 6000 ft early in the period and again toward mid-day Saturday. Could also see some spotty showers Saturday out of said clouds with the highest likelihood at OFK and OMA, but chances are under 20%. There are once again hints at patchy fog development early Saturday, but confidence in impacts at TAF sites is low. Otherwise, winds should remain under 10 kts, with OFK turning clockwise and settling at northeasterly, and OMA and LNK going from southwesterly to southeasterly.

OAX WATCHES/WARNINGS/ADVISORIES

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