textproduct: Des Moines

KEY MESSAGES

- More precipitation is possible late Thursday night and Friday central and south.

- Hot and humid conditions arriving by Sunday and into next week. Heat index values over 100 expected.

UPDATE

Issued at 624 AM CDT Thu Jun 25 2026

Forecast is largely on track this morning but did increase PoPs across the far southwestern portions of the CWA due to present radar trends.

SHORT TERM /THROUGH FRIDAY/

Issued at 252 AM CDT Thu Jun 25 2026

As of the latest surface analysis, yesterdays cold front has crossed through the state and is currently starting to settle in northern Missouri and western Illinois. The parent surface low has ejected eastward out of central Minnesota into southern Wisconsin. Behind the departing cold front, surface high pressure, presently centered over southeastern Saskatchewan, is exerting its influence across much of the northern Plains and Midwest, including Iowa. High pressure has allowed for mostly clear skies overnight, with temperatures ranging from the lower 50s across the north to the mid- 60s along the IA/MO border. While surface high pressure is largely dominating the current conditions, high clouds are streaming off a separate surface low that is presently sitting over the High Plains of eastern Colorado.

Through the remainder of the overnight and much of the day today, surface high pressure will dominate the forecast, leaving the area mostly dry. Although shower and/or thunderstorm development along the distant cold front is possible, forecast soundings indicate a deep layer of dry air in place across the region. This would lead to the evaporation of any precipitation attempting to reach the surface. This likely scenario is highlighted in the HREF PoP probs, which shows a 10% chance or less of seeing at least 0.01 inches of QPF today. Persistent upper-level northwesterly flow will advect cooler temperatures into the area, leading to highs maxing out in the upper 70s.

By this afternoon and evening, the upper-level trough is forecast to flatten into a quasi-zonal flow. However, the shortwave trough responsible for the low in Colorado will slowly eject eastward through the overnight hours. The track of this low is forecast to stay mainly south of the CWA, moving through Kansas and Missouri, but its precipitation shield may skirt the far southern portions of the CWA beginning late Thursday night and continuing through Friday evening. Areas along and south of US Highway 30 have the best chances, albeit 40% or less, of seeing some showers overnight, followed by showers and storms during the day on Friday. Behind this departing surface low and through the end of the forecast period, upper-level height rises are forecast to build into the region, bringing both a warming trend and dry weather.

In summary, high pressure will bring mostly clear, dry conditions and cooler temperatures to the region today. While dry low-level air will prevent precipitation during the day, a secondary surface low tracking south of the area through Kansas and Missouri may bring a chance of showers and thunderstorms to southern portions of the CWA from Thursday night through Friday evening. Following this system, building upper-level ridging will return dry weather and a warming trend to the area.

LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/

Issued at 234 PM CDT Wed Jun 24 2026

Theta-e advection will lift into Iowa Thursday night and Friday as an upper low pressure begins to descend from the Gulf of Alaska with troughing extending across the entire western CONUS. This will lead to 1000-500 mb height rises into Iowa and the push of theta-e advection northward. Showers and a few storms will be possible, mainly over central and southern Iowa. A more significant push of theta-e advection and of much warmer temperatures begins Saturday afternoon and night as the upper low further descends into the Pacific Northwest while a sub-tropical high begins to form over the Lower Mississippi Valley. Note, the location of the sub-tropical high has been trending west the past 48 hours, which would place Iowa in potentially an even warmer/drier solution. Still the potential for elevated convection as the theta-e advection and instability/low level jet pass through Iowa. A stout elevated mixed later should then develop leading to hot and humid conditions for Sunday and Monday. Highs in the 90s and heat index values over 100 are expected. Still monitoring Tuesday/Wednesday as potential timeframe where the sub-tropical high flattens some as the western upper low moves northeast. This could lead MCS develop and track into parts of Iowa that may suppress the heat, at least across northern Iowa. A sneak peek beyond Wednesday does look like the sub- tropical high becomes re-established even further north bringing back the heat, potential for the end of next week and into the Fourth of July weekend.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 624 AM CDT Thu Jun 25 2026

Fairly quiet TAFs are in store as surface high pressure largely dominates the period. A passing disturbance to the southwest will bring increased clouds to KDSM and KOTM this morning but CIGS are expected to be around 10K ft. Also, afternoon cumulus is forecast to develop around 4K to 5K with increased winds from the northwest will impact the remaining TAF sites but when sunset arrives, winds will diminish to light and variable. As a surface low approaches from the west, increasing showers are expected after 09Z for KOTM and KDSM.

DMX WATCHES/WARNINGS/ADVISORIES

None.