textproduct: Des Moines

KEY MESSAGES

- Flash Flood Watch issued for portions of northwest Iowa through Monday morning.

- Storms continue into Monday morning. Another round of severe storms possible Tuesday afternoon.

- Cooler temperatures and lower humidity arrive late week.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 322 PM CDT Sun Sep 6 2026

We kick off the first Sunday of September on an active note. Showers and storms have lingered throughout the morning and into the early afternoon, fueled by areas of deep moisture convergence. CAMS suggested the potential for more organized cells to form due later on increasing shear, but this has not yet materialized. Convection continuing to develop ahead of the main line is disrupting inflow to the primary updrafts and preventing the development of a single dominant cold pool. Currently, storms are feeding off a robust instability axis with MLCAPE around 3000 J/kg although effective shear around 30 kts is keeping activity disorganized. Regardless, a few severe storms still remain possible with damaging winds being the primary concerns. Slow storm motions and efficient rain have led to some areas recording 3-5 inches of rainfall as storms train over the same areas. With storms expected to persist through the afternoon, CAM QPF highlight localized maximums potentially exceeding 5 inches over west central Iowa. Consequently, the weather prediction center (WPC) has outlined much of northwest Iowa in a Moderate Risk for flash flooding, and a Flash Flood Watch is in effect. Somewhat mitigating the flash flood threat are the dry antecedent conditions; much of NW Iowa remains in a moderate drought, with Ida County experiencing a small sliver of severe drought.

Tonight

Convection will continue to slowly shift south and east this evening, gradually weakening with the loss of diurnal heating. However, a Strengthening low level jet across central and western Iowa could reignite scattered showers and storms late tonight into early tomorrow morning. Severe weather is not expected overnight as MUCAPE values drop to around ~500 J/KG.

Monday into Tuesday

Overnight showers and storms should diminish as we head into tomorrow morning and drier air filters in for Monday. Winds across northern Iowa will be breezy ahead of an approaching cold front, at with gusts reaching up to 25 mph at times. Additional storms are possible ahead of this boundary late Monday night into Tuesday morning. A severe weather threat may materialize by Tuesday afternoon; the Storm Prediction Center (SPC) day 3 highlights central Iowa in a Marginal Risk. Details regarding this severe threat will be fine tuned in future AFD issuances.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Issued at 322 PM CDT Sun Sep 6 2026

Storms will exit the region behind the cold front on Wednesday, ushering in cooler temperatures and lower humidity. Highs in the lower 80s are expected through Thursday, with precipitation chances potentially returning by Friday.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1240 PM CDT Sun Sep 6 2026

Most of central Iowa is under at least MVFR conditions due to diurnal cumulus bubbling up. IFR conditions are present at KMCW due to lower ceilings. Storms are expected to increase in coverage across western Iowa and portions of central Iowa. PROB30 groups have been introduced at KDSM and KFOD to highlight this. VFR conditions are expected to return overnight and winds will increase towards the end of this TAF insurance across northern Iowa.

DMX WATCHES/WARNINGS/ADVISORIES

Flood Watch through late tonight for IAZ004-015-023-033-034- 044.