textproduct: Des Moines

KEY MESSAGES

- Sunny and cool today.

- Showers and thunderstorms return Thursday in western Iowa, expanding across much of Iowa Friday and Saturday. Severe storms are not anticipated but pockets of heavier rain are possible.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 214 AM CDT Wed Sep 23 2026

Low stratus across Iowa continues to erode from east to west early this morning and high pressure across the Great Lakes entrains dry dry to the region. In areas that have seen clear skies tonight temperatures have already fallen to the upper 40s at 2am. Temperatures will continue to fall in those areas overnight and in other areas farther west as the cloud deck diminishes. Some patchy fog may be possible in areas that see overnight clearing, however conditions will likely remain dry enough to prevent any widespread fog development. Clearing will allow for a cool but pleasant day with sunny skies and highs in the mid to upper 60s across the area as a narrow ridge lifts into the state today.

Overnight a shortwave will move across the northern plains, squashing the ridge back south and inducing an area of convergence. A plume of moisture will increase across Nebraska and South Dakota with moisture transport is pulled east by the approaching shortwave. This will help to induce showers and a few thunderstorms in western Iowa on Thursday, staying west of I-35 for the most part. The HRRR is a notable outlier, pulling light showers across central Iowa through the day on Thursday while nearly every other model maintains precipitation across northern and western Iowa until later Thursday evening. There is very little in the way of instability and meager shear so severe storms are not anticipated, though the increasing moisture will create an environment for efficient rain production. Once again warm cloud depths grow to 4000+m with PWATs around 1.8". With less convective activity due to low instability widespread heavy rain is not expected, but pockets of higher totals are possible, and with a rainy month thus far soil capacity is decreased.

LONG TERM /FRIDAY THROUGH TUESDAY/

Issued at 155 PM CDT Tue Sep 22 2026

Intermittent showers and storms will persist Friday into Saturday as low level QG convergence and theta-e advection slowly move eastward. While it will not be days full of rainfall, the days will be more common to the ones we have had recently with plenty of clouds and times of precipitation. While there will be instability for occasional storms, the higher instability and overlapping shear is displaced west of the area. Thus, locally heavy rainfall continues to be the main concern due to the antecedent wet conditions. While soils will have a 24 to 48 hours break with dry conditions, infiltration capacity will remain reduced along with elevated streamflows. Rainfall totals still look on track between 1 and 3 inches on the high end with ensemble probabilities of a 1" of rainfall in 24 hours between 45 and 55% over western Iowa Friday morning into Saturday morning dwindling to 20 to 30% chance over central Iowa Saturday morning through Sunday morning. A break in the rainfall will arrive as another shortwave trough lifting northeastward or eastward moves through the region. This should bring large scale subsidence into the area on Sunday providing drier conditions that may last into at least Monday. Temperatures late this week into early this weekend will remain on the cool side.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1238 PM CDT Wed Sep 23 2026

MVFR cumulus has developed over eastern Iowa but cloud bases will continue to diurnally rise this afternoon. A early period of MVFR is possible at KALO/KOTM through 19-20z. Less confidence elsewhere and by the time an BKN cigs do develop, bases should be above 3 kft. The cumulus will erode tonight while cirrus begins to increase. Cumulus may redevelop by mid Thursday morning with a few showers possibly reaching KFOD late. East to southeast wind, mainly below 12 kts.

DMX WATCHES/WARNINGS/ADVISORIES

None.