textproduct: Des Moines

KEY MESSAGES

- Cooler temperatures will be in place through Friday, then increase through the 90s this weekend into early next week.

- Showers are expected to increase in coverage overnight tonight into Friday, with pockets of heavy rain possible in southwest Iowa.

- Additional showers and storms are possible later this weekend into early next week, with some potential for severe weather. Timing and location will be better determined in the coming days.

SHORT TERM /THROUGH FRIDAY NIGHT/

Issued at 240 PM CDT Thu Jul 23 2026

Surface analysis this afternoon shows a large area of high pressure centered over the Ohio Valley, extending westward across Iowa. Light south/southeast winds are noted over the state, with much of the area seeing diurnally driven cumulus development given the presence of moisture aloft, as temperatures increase into the mid to upper 70s. Satellite imagery is also detecting a thin area of smoke over the Northern Plains that extends over into parts of far northern Iowa, though this shouldn't extend further south and will also remain aloft. More notable mid-level moisture content is noted over South Dakota through western Missouri, as seen from a thicker blanket of clouds in these areas, which will gradually shift eastward this evening into Friday. Increasing mid-level vorticity advection and low-level theta-e advection into Iowa, especially over far southern Iowa into northern Missouri in conjunction with a passing shortwave riding the western CONUS thermal ridge will allow for increasing chances for rain later tonight. One of the challenges that remain is the exact timing of full saturation of the column, given the notable low level dry column of air that remains overhead as the surface high pressure will continue to influence much of the state. While the shortwave arrives over western Nebraska late this afternoon to evening, will likely see some light returns on radar over western Iowa indicating rain falling through the dry low levels, before better saturation occurs generally after midnight over west/southwest Iowa from a push of low-level moisture and forcing as the low level jet increases over far western Iowa late tonight into early Friday. Latest guidance continues to trend lower on overall rainfall amounts as the axis of heaviest rainfall shifts a bit further south out of Iowa, now generally over eastern Nebraska into northern Missouri where better forcing and moisture availability is indicated. However, the potential for heavy rain still exists mainly Friday morning, given PWATS around 1.75-2 inches and warm cloud depths around 15 kft. While dry antecedent conditions and mature crops should largely mitigate concerns for flooding, a low potential for very localized flash flooding cannot be ruled out in an urban area in southwest Iowa. Minimal instability and weak shear will keep the storm potential very low, though some occasional thunder cannot be ruled out at times. Rain showers are generally expected to remain over central to southern Iowa throughout the morning before tapering off, though portions of far southern Iowa could still see some lingering showers throughout the majority of the day. Total rainfall amounts are generally expected to remain under an inch, with localized areas of 1-2 inches possible in southwest Iowa where any heavy rain potential lies.

Thick cloud cover overhead throughout the day, along with the rain and light southeast flow will result in slightly cooler temperatures than in previous days, with below normal values in the mid 70s for most areas, and some isolated upper 70 values in northern Iowa where less cloud cover is anticipated. Certainly a perfect day to spend time outdoors once the rain ends!

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Issued at 240 PM CDT Thu Jul 23 2026

As the thermal ridge nudges further eastward into the weekend and early next work week, a stronger push of low-level southwesterly flow will bring warmer and more humid air into the Central Plains. This pattern shift will allow for temperatures to rise significantly with values through the 90s, especially Sunday and Monday. Dewpoint values topping out through the 70s, paired with these temperatures, will lead to heat index values near 100-105+ degrees over western Iowa Saturday, and much of the area Sunday and Monday. The upper level northwesterly flow into Iowa though in relation to the closer proximity of the thermal ridge will also introduce additional chances for showers and thunderstorms, particularly into Sunday morning and again late Sunday into Monday. Smoke also could limit highs a bit Saturday as guidance suggests a return through the day. All important things to watch over the coming days, but at least in terms in heat headlines, the potential is certainly there for some areas of Central Iowa. The warm and moist airmass Sunday through early next week will bring about to a substantial increase in instability and favorable shear profiles to reintroduce severe weather potential as various shortwaves round this ridge into the Midwest. At this time, guidance suggests, as mentioned earlier in this paragraph, early Sunday morning and especially late Sunday into Monday morning with the increasing LLJ into Iowa to be possible targets for some potential severe weather, with the SPC highlighting north/northeast Iowa in a 15% risk. Will keep a close eye on this over the coming days as details become more clear. The thermal ridge by midweek next week moves very little, with Iowa still in the ring of fire as additional waves are indicated in long term guidance to pass through, keeping the pattern more on the active side.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1237 PM CDT Thu Jul 23 2026

Areas of diurnal cumulus are expected to increase in coverage through this afternoon before fading after 00-01z, with ceilings near MVFR at times. Otherwise, will see a gradual increase in mid to upper level clouds this evening and especially through Friday morning as a system approaches the region. Rain showers are expected to increase across the state mainly after 06z, with impacts mainly expected to occur at KFOD, KDSM and KOTM. Adjustments on exact timing are expected to continue over the next few issuances in accordance with latest model trends. Winds will generally remain light out of the southeast today, then increase with slightly breezy winds near the end of the current period.

DMX WATCHES/WARNINGS/ADVISORIES

None.