textproduct: Des Moines

KEY MESSAGES

- Another cool, cloudy, and wet period expected through Sunday. Expect several rounds of rainfall along with a few embedded thunderstorms. No severe weather is expected.

- High confidence /70-100%/ that portions of Iowa will receive over 1+" of rainfall by Sunday with portions of western and southwestern Iowa having a 30-70% chance of seeing 2+".

- Another strong storm system expected Tuesday and Tuesday night. Thunderstorms with additional heavy rainfall possible.

- Temperatures generally remaining below average due to clouds and precipitation with highs in the 60s and low 70s.

SHORT TERM /THROUGH SATURDAY/

Issued at 213 AM CDT Fri Sep 25 2026

The synoptic pattern early this morning is dominated by a stagnant/blocked upper air pattern with troughing over both the east and west coasts, with modest ridging over the central CONUS. A series of upper level shortwaves will eject out the mean western trough, moving through the central Plains and upper Midwest over the next 36-48 hours.

Today... Early this morning, one such impulse/PV anomaly will move across the Corn Belt. The combination of low level theta-E advection and modest upper ascent /Q-vector convg/ has lead to the development of widespread showers generally south of US Highway 20. Rainfall since 7pm /00Z/ last evening has not been particularly heavy, with most areas picking up less than 0.25". Portions of west-central IA have seen pockets of heavier rainfall, with several automated gages and MRMS precip estimates showing 0.40-0.65." Expect periods of rainfall to continue through at least mid- afternoon today across the southern 2/3rds of Iowa. By late afternoon, this batch of forcing/lift will shift ewd and weaken, with soundings/time-sections showing a brief period drier air and reduced deep layer saturation, with showers diminishing for a time. Expect additional rainfall today in the 0.10 to 0.50" range. Due to the modest rainfall rates, not expecting any significant hydrologic response except some minor ponding or within bank rises on rivers. Model plan view and soundings show very little instability/CAPE today due to weak, moist adiabatic lapse rates, so nothing more than an isolated lightning strike expected, and even that maybe overdone. With abundant cloud cover and precip, expect cool high temps in the 60s.

Friday night and Saturday... Another shortwave ejecting out the western trough will induce a second surge in the LLJ, with a period of enhanced of WAA/moisture convergence returning Friday night into Saturday. Scattered to widespread showers will re-develop and move from west to east across the entire state late Friday night into mid- morning Saturday, with the heaviest rainfall expected along and south of US Highway 30, where 0.5" to locally 1" is possible. On Saturday afternoon, the global and CAM solutions show better instability /250-1000 J/kg/ is possible across southern Iowa due to slightly steeper mid-level lapse rates and higher low level level moisture/Tds. This will likely lead to move convective elements and thunderstorm activity, which could boost rainfall rates for a time. This activity will likely continue into the evening, with another "lull" in the activity Saturday night as the lift weakens. Depending on the location of the heaviest QPF axes, additional within bank rises are likely on area rivers. If higher magnitude QPF solutions verify /90th percentile/ then a few rivers could approach flood stage. Some to watch in the upcoming days.

LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/

Issued at 251 PM CDT Thu Sep 24 2026

Dryer air will arrive from west to east late Saturday night into Sunday though mostly cloudy skies are expected to persist. Monday will be mostly dry and slightly warmer with highs in the 60s to near 70. Another strong short wave will arrive Tuesday and Tuesday night. PWAT values will approach 2 inches and conditions will be favorable for rainfall amounts of 1-2 inches. Note, Des Moines is currently a little over 2 inches from the September record for precipitation. This will be approached with the system this weekend and the one early to mid next week.

For Wed into the end of the week, models are taking turns trying to ingest the Pacific Hurricane Palo into southwest flow as a strong upper level low approaches the Four Corners region. There remains a lot of uncertainty here regarding this ingestion and the overall evolution of the upper level low but a slower progression of everything may lead to more wet weather for Iowa.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 630 AM CDT Fri Sep 25 2026

Periods of rain showers moving through the area will lead to prevailing IFR conditions at KFOD/KDSM/KOTM through at least the afternoon hours, with intermittent LIFR are likely at times. At KALO/KMCW, mostly MVFR conditions expected, perhaps bouncing down to IFR at times. Conditions could briefly improve this evening, before another round of widespread rain and IFR conditions moves in again from west to east tonight. Winds will remain out of the E/SE.

DMX WATCHES/WARNINGS/ADVISORIES

None.