textproduct: Des Moines

KEY MESSAGES

- Periodic chances for storms through Monday, mainly over the western half of Iowa. Damaging winds are possible with storms.

- Gradual cooling into Monday followed by more seasonal temperatures.

SHORT TERM /THROUGH TUESDAY/

Issued at 239 PM CDT Sat Sep 5 2026

Convective debris and an outflow boundary impacted parts of central and northern Iowa today. The outflow boundary has been eroding early this afternoon but this boundary in addition to the clouds, have kept the Highway 30 corridor and northward cooler yet still humid today. A few showers did linger over far north central Iowa but trends have continued downward.

That Convective trends will the primary challenge over the next 36- 48 hrs. There is already diurnally driven isolated thunderstorms over far northern Missouri. This potential may reach far south central Iowa where agitated cumulus along a wind shift line is present. The low level jet will ramp up again tonight across the western High Plains while the instability axis does move farther east into central Iowa. Thunderstorms are expected to develop over parts of South Dakota and southwest Minnesota and eventually become organized and follow the Corfidi vectors southeast into Iowa along the instability axis. These storms may pose a damaging wind threat later tonight and into Sunday morning. This process may repeat again Sunday night into Monday morning. The elevated mixed layer (EML) is expected to become re-established Monday afternoon and should end precipitation chances for a period. An upper level low moving into Montana then Manitoba will squash the upper ridge enough to allow a boundary to enter Iowa by Tuesday, which will bring the next chances for thunderstorms and cooler weather.

LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/

Issued at 239 PM CDT Sat Sep 5 2026

The flattening of the sub-tropical high will continue Wednesday with a westerly/zonal flow for the mid to end of the week. Less certainty late next week with spatial and temporal differences with the next strong upper level short wave that will arrive into the Pacific Northwest. This will determine how much the sub-tropical high ridging can become re-established over the western CONUS and the difference between seasonal westerly flow or cooler northwest flow and attendant precipitation chances associated with each.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1046 PM CDT Sat Sep 5 2026

VFR conditions prevail this evening, although isolated areas of low clouds (1500 ft) and patchy fog have started to develop over portions of Iowa. Expectation is still that northern and eastern sites (KMCW, KFOD, and KOTM) will be most impacted by low cloud and fog development as skies clear out through the morning.

Isolated to scattered shower and thunderstorm chances still remain possible in the morning, mainly near KFOD and KDSM. Guidance isn't overly confident in this occurring, but there's a strong enough signal for at least PROB30 mention at both sites in the morning. More widespread chances then look to move in from the west in the afternoon. Again, guidance is struggling to resolve this, but increasing rain and thunder chances are expected through mid-day and the afternoon.

DMX WATCHES/WARNINGS/ADVISORIES

None.