textproduct: Des Moines

KEY MESSAGES

- Mostly dry today with more pleasant temperatures in the 80s.

- Additional thunderstorm chances late tonight into Sunday morning and Sunday night into Monday though uncertainty remains. A few strong to severe storms and locally heavy rain remains possible.

- Heat indices climb again Sunday with feel-like temperatures in the 90s and may even top 100 pending cloud cover from any early day convection.

- Active weather persists through much of next week.

SHORT TERM /THROUGH SUNDAY/

Issued at 328 AM CDT Sat Aug 8 2026

Storms have moved out of the state early this morning though the surface boundary remains in our far southeast as noted in the wind fields. Surface high pressure has already started to nudge into the area and will cross through the state today, departing to the east tonight. Cooler and drier conditions are associated with this feature with portions of northern Iowa already seeing temperatures and dew points in the 50s early this morning (vs 70s temperatures/dew points in southern Iowa). These cooler and drier conditions will translate to a more pleasant day today with highs similar to yesterday and in the 80s, but with feel-like temperatures also in the 80s and conditions less humid compared to yesterday's heat indices rising into the 90s in much of central to southern Iowa. Light winds and clear skies has once again led to patchy fog development this morning with some sites in east central and west central Iowa reporting visibilities below 1 mile, and as low as 1/4 mile. Although overall expectation is for fog to be more transient and not be as widespread dense as it was this time yesterday (into Friday morning), patchy fog that is locally dense at times, remains likely into this morning. Will continue to evaluate any fog headline needs over the next few hours. Any fog will begin to clear after sunrise. Despite the otherwise clear conditions expected beyond the fog dissipating this morning, skies may remain hazy with another big push of wildfire smoke moving in aloft.

The forecast for this evening and beyond is much more complex with many unknowns still lingering. What is known is that flow returns from out of the south to southwest tonight with a big push of theta- e advection moving through tonight into Sunday morning. Moisture surges back in late tonight into the overnight as an around 35 knot low level jet ramps up and points through the area. With this, instability will increase with forecast soundings indicating around 1000-2000 J/kg or more of MLCAPE around 09Z (4am Sunday), steep lapse rates, and shear of 25-35 knots (or more). Dry air through the lower 3 km lead to DCAPEs above 1000 J/kg but warm mid-levels suggest a CAP will be in place. The frontal boundary will lift back north into Sunday morning and albeit weak, shortwave energy crosses through the area. With the weak forcing, the location for storm development remains one of the biggest unknowns but given the parameter space just noted, storm development is expected somewhere. CAMs are having a hard time coming to any kind of consensus though eastern into northeast Iowa seem the most likely at this point from the later half of the overnight into Sunday morning. These certainly could become elevated hailers, and with the dry air, some gusty winds are also possible but the overall severe threat is low and SPC has retained the Day 1 Marginal (Level 1 of 5) for a good portion of the area given the uncertainty in timing, location, and extent of storm development. Warm cloud depths and Pwats over 1.5" could lead to some localized heavy rain as well.

Some models are hinting at some gusty winds developing on the backside of whatever storms are able to develop on Sunday morning (mainly in the northeast/east) but dry conditions look to return until the evening/overnight when storms reactivate along the front or any lingering outflow/low level convergence zones. With the thermal ridge nudging closer to the area, Sunday will also be hotter again with highs in the 80s to low 90s but with the surging dew points sending feel-like temperatures back into the 90s and maybe even low 100s pending lingering cloud cover from any early day convection.

LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/

Issued at 243 PM CDT Fri Aug 7 2026

Upper high pressure over Hudson Bay combined with upper high pressure over the Four Corners region, will lead to progressive westerly flow over much of the northern CONUS with periodic embedded short waves passing across Iowa. This flow will also keep a surface boundary in the Midwest area and resulting in several chances for thunderstorms before Canadian high pressure arrives early next week. PWAT values of 1.50-2.00" will be common during active storm periods that could lead to an aggregate heavy rain threat through the week. Temperatures will be seasonal and mainly in the 80s through midweek the gradual cooling as the Canadian high pressure approaches for the end of next week.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 635 AM CDT Sat Aug 8 2026

Patchy fog is once again in place this morning, but is not nearly as widespread as Friday morning. Some localized MVFR to LIFR conditions associated with this patchy fog to start the day will quickly become back to VFR after sunrise and the fog dissipating. Skies may remain hazy due to wildfire smoke and addressed with SCT250 deck at all terminals during the daytime. Confidence in shower/storm location and timing tonight remains low, but did start with some prob30 shower mentions at eastern terminals (KMCW, KALO, KOTM) overnight. Confidence in thunderstorms remains lower, as does further impacts than the VFR conditions advertised, though lower visibilities or ceilings may occur. Winds light and variable to out of the north early become out of the east and then southeast through the day today, but generally remain below 10 knots.

DMX WATCHES/WARNINGS/ADVISORIES

None.