textproduct: Des Moines

KEY MESSAGES

- Widespread shower and storm chances expected on Sunday.

- Increased severe weather and heavy rain chances on Monday. Heavy rain potential continues through mid- week.

LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/

Issued at 249 PM CDT Fri Sep 11 2026

The pattern turns quite active starting Sunday night, as deep layer moisture increases ahead of an approaching 500 mb trough and multiple subsequent waves keep the gulf moisture stream open through the first part of the week. The first day of concern will be Monday as the aforementioned 500 mb trough passes through the northern CONUS. This will bring a push of low level moisture and increasing temperatures up into Iowa, along with strong mid and upper level flow. Instability values in our area will maximized Monday afternoon, with plenty of shear for organized storms. Fortunately, a warm nose aloft will work to keep the atmosphere capped off and activity surface based, at least at this lead time. Still, strong 850 mb winds could certainly support some damaging winds. The storm prediction center has already started to key in on Monday, with a Day 4 15% risk over central Iowa.

The active weather continues through at least Tuesday and Wednesday, although the pattern looks to transition to more of heavy rainfall threat through these next two days. Modeled PWATs around 1.9 to 2" will be conducive for efficient rainfall, and multiple days of convection along a quasi-stationary boundary could lead to some flooding concerns. It's still a bit early to get too ingrained in details, as mesoscale factors could cause this boundary to sink or move around, but the current synoptic setup certainly points towards potential hydrology concerns through next week. The weather prediction center is already on top of this as well, with slight risks for excessive rainfall spanning from Sunday to Tuesday of next week.

LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/

Issued at 638 AM CDT Sat Sep 12 2026

The pattern turns quite active starting Sunday night, as deep layer moisture increases ahead of an approaching 500 mb trough and multiple subsequent waves keep the gulf moisture stream open through the first part of the week. The first day of concern will be Monday as the aforementioned 500 mb trough passes through the northern CONUS. This will bring a push of low level moisture and increasing temperatures up into Iowa, along with strong mid and upper level flow. Instability values in our area will maximized Monday afternoon, with plenty of shear for organized storms. Fortunately, a warm nose aloft will work to keep the atmosphere capped off and activity surface based, at least at this lead time. Still, strong 850 mb winds could certainly support some damaging winds. The storm prediction center has already started to key in on Monday, with a Day 4 15% risk over central Iowa.

The active weather continues through at least Tuesday and Wednesday, although the pattern looks to transition to more of heavy rainfall threat through these next two days. Modeled PWATs around 1.9 to 2" will be conducive for efficient rainfall, and multiple days of convection along a quasi-stationary boundary could lead to some flooding concerns. It's still a bit early to get too ingrained in details, as mesoscale factors could cause this boundary to sink or move around, but the current synoptic setup certainly points towards potential hydrology concerns through next week. The weather prediction center is already on top of this as well, with slight risks for excessive rainfall spanning from Sunday to Tuesday of next week.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 638 AM CDT Sat Sep 12 2026

VFR TAFs are on tap through the TAF period as weak surface high pressure builds in from the northwest. However, post-frontal MVFR CIGS may sneak into the TAFs this morning as the front drops southeast through the area. Post-frontal northwesterly winds will start to pick up with gusts upwards of 20 knots and persist through the day before starting to diminish toward 00Z/Sunday especially at KFOD, KMCW and KALO.

DMX WATCHES/WARNINGS/ADVISORIES

None.