textproduct: Des Moines

KEY MESSAGES

- Precipitation chances increasing over western Iowa on Thursday.

- Periodic showers and non-severe thunderstorms Friday and Saturday.

- Another strong system will arrive Tuesday next week.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 233 PM CDT Wed Sep 23 2026

High pressure ridging remains over eastern Iowa though the most abundant sunshine today was on the west side of the ridge across central Iowa. Widespread cumulus developed under the ridge and did move westward following the westerly steering flow. The cumulus will erode later this afternoon and evening with the loss of diurnal ascent. The primary high pressure center will be over southern Quebec and southeast Ontario. This system will have a significant influence on the weather across the eastern CONUS and into Iowa Thursday and through the weekend. This system won't move much overall into the weekend but it will begin to become more positively tilted. The tilting will result in increasing moisture moving into northwest Iowa and Minnesota on Thursday. The deepening moisture profiles along with modest vertical ascent associated with theta-e advection will bring increasing shower and isolated thunderstorm potential.

LONG TERM /FRIDAY THROUGH WEDNESDAY/

Issued at 233 PM CDT Wed Sep 23 2026

Numerous waves of theta-e advection will occur into Friday with precipitation chances increasing further east into central Iowa as Lee side cyclogenesis occurs over eastern Colorado to Wyoming. The cyclogenesis will push additional moisture into Iowa and bring more widespread potential for showers and a few non-severe thunderstorms. PWAT values Friday night and Saturday will be over 1.5 inches over Iowa along with 850 mb dew points near 12C and warm cloud depths near 13 kft. These parameters will be favorable for warm rain processes and a efficient rain producing system. Deep convection will be lacking, which in this case, maximum rainfall rates are not expected. The deep layer moisture will diminish on Sunday but stratus may linger over parts of Iowa into early next week. A potent upper level system remains on track to impact Iowa Tuesday and Tuesday night. Locally heavy rainfall and perhaps a few strong storms will be possible.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 630 PM CDT Wed Sep 23 2026

Cumulus will continue to decrease in coverage over the next few hours, though mid to upper cloud cover will increase across Iowa through the next several hours, which is expected to bring a gradual lowering of ceilings through Thursday. VFR conditions will generally occur until after 15-18z, then becoming MVFR, especially near the end of the period. PROB30 groups have been introduced at KFOD for -SHRA into mid to late morning, but remain dry at the other sites, though will likely be introduced in later issuances.

DMX WATCHES/WARNINGS/ADVISORIES

None.