textproduct: Des Moines

KEY MESSAGES

- Thunderstorms possible late tonight into early Sunday. A few strong storms with large hail could occur.

- Warm and humid Sunday with heat indices near 100.

- Active weather persists through much of next week with periodic chances for thunderstorms along with the potential for a few strong storms and heavy rainfall.

SHORT TERM /THROUGH SUNDAY/

Issued at 235 PM CDT Sat Aug 8 2026

High pressure is centered across Iowa this afternoon and is responsible for the drier and cooler airmass across Iowa. Afternoon dewpoints remain in the 50s over northern Iowa. Return flow on the backside of the high has commenced over the far southwest portion of the state and into Nebraska. Dew points are back in the low to mid 70s at Shenandoah and Red Oak. Thunderstorms are still ongoing over far southeast Nebraska, fueled by the deeper layer moisture return. While these storms have become outflow dominant and in a decaying state, new updrafts are developing along the outflow, which will help keep the complex together long enough to reach far southwest Iowa, where the return flow is already in place. Storms will stay elevated above the elevated mixed layer (EML), which is in place over the area over the area.

The return flow will intensify tonight as the low level jet ramps up to 50-60kts this evening across eastern Nebraska into far western Iowa before veering east into the central portion of Iowa. As this occurs, mid-level moisture saturation and increasing instability will increase leading to the potential for elevated thunderstorm development. Mid-level lapse rates of 8-8.5 C/km in the 700-300 mb layer are expected and that will help increase most unstable CAPE values to 1000-2000 J/kg and lead to updraft accelerations capable of producing large hail. The potential for damaging wind gusts is low considering how elevated the storms are and it would require a subsidence producing features such as gravity waves for winds to reach the surface.

The EML will intensify on Sunday with very warm and humid conditions across most of the state in the wake of the overnight/early morning storms. A weak boundary will be stretched across Iowa on Sunday but it will have little impact on dew points, that will be in the 70s. In addition, a vast amount of wildfire smoke moved across Iowa today. That smoke will continue to stream across the state at times through at least mid-week with westerly flow aloft established. The smoke may be opaque enough for sufficient solar filtering to lower potential high temperatures by a few degrees.

LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/

Issued at 235 PM CDT Sat Aug 8 2026

The predominant westerly flow aloft will keep the surface boundary in the vicinity of Iowa through much of next week. This will have a couple impacts. First the wildfire smoke listed above will persist at times. In addition, the active weather pattern will persist with periodic chances for thunderstorms. The storms will bring an attendant chance for severe weather and the potential for heavy rainfall. At this time, it appears that dryer air and Canadian High pressure may bring a brief reprieve of the active and humid weather but already there are hints that return flow and active weather could again return again sometime next weekend.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1238 PM CDT Sat Aug 8 2026

VFR conditions today with light and variable wind becoming southeasterly. Scattered thunderstorms will develop overnight and may impact most sites between 09-14z Sunday. Otherwise VFR conditions will persist along with increasing south wind by mid to late Sunday morning.

DMX WATCHES/WARNINGS/ADVISORIES

None.