textproduct: Des Moines

KEY MESSAGES

- Hot and humid weather continues today through the weekend.

- Isolated shower possible in the afternoon to early evening.

- Heat peaks on Monday, then a return to the low to mid 80s next week.

SHORT TERM /THROUGH SATURDAY/

Issued at 224 AM CDT Fri Jul 17 2026

The thermal ridge continues to dominate the near term pattern, with a trough sitting to the northeast across the Great Lakes region. A weak pseudo boundary stretches across northern Missouri with scattered cloud cover in place there and into southern Iowa early this morning. The rest of the area is clear, warm, and humid this morning with temperatures in the low to mid 70s at 2 am. Patchy light fog is possible towards sunrise with plenty of available moisture but widespread or dense fog is not anticipated.

This afternoon will be hot and humid once again with highs in the low 90s and dewpoints around 70. As was the case on Thursday, an isolated shower is possible again this afternoon into the evening mainly in the southern half of Iowa near that weak boundary. There is very little shear to organize convection, but with 1500+ J/kg of MLCAPE there will plenty of instability to support short lived airmass showers. On Thursday these collapse before even producing lightning and that will likely be the case again today should any develop.

The Great Lakes area trough deepens on Saturday and pulls a cool front across Iowa, keeping northern Iowa in the mid 80s while central and southern Iowa warm into the low 90s once again. By afternoon to evening a few thunderstorms are possible along the weak front as it sinks south across southern Iowa. With little to no shear, severe storms are not expected. Theta e advection increases across the area on Sunday with low 90s areawide. As that front is shoved back north and east a few thunderstorms are possible, but there is uncertainty in the placement and whether those may be east of the are on Sunday.

LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/

Issued at 208 PM CDT Thu Jul 16 2026

The high continues to be pinched off as an upper level ridge builds over the western CONUS this weekend and early next week. Uncertainty lies in how quickly this happens. LREF clusters hint that we could be out from under the ridge as soon as Sunday night/Monday, although it is most likely that we stay under it or on the edge through the day Monday. A surge of warmer air enters the area this weekend just before the ridge translates away from us, leading to the potential for the highest temperatures of this stretch to end the weekend. The Extreme Forecast Index (EFI) is keying in on this, highlighting part of Iowa as having above normal temperatures. With this still being several days out, it is a trend to monitor. Of note, long-term deterministic models key in on this as well. In tandem, uncomfortably warm low temperatures are being forecast for the same time period.

Once we are out of the ridge's area of influence, we get into a northwesterly flow regime which leads to a change of pattern and increased potential for shower and thunderstorm chances across the region at times next week.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 628 AM CDT Fri Jul 17 2026

VFR conditions will prevail through the TAF period. Light fog has develop this morning with MVFR visibility in some locations, though missing all TAF sites at this time. Any remaining fog this morning will dissipate quickly in the next our or so. Wind will be from the southwest at 5-10 kts today with mostly clear skies. An isolated shower is possible this afternoon, however these will be very short lived and widely scattered if they develop, therefore did not include a mention in any TAF.

DMX WATCHES/WARNINGS/ADVISORIES

None.