textproduct: Des Moines

KEY MESSAGES

- Marginal (Level 1 of 5) Risk for severe weather across southern Iowa. Damaging winds and large hail are the primary threats.

- Fairly consistent highs through midweek next week, ranging from the 70s to low 80s across Iowa.

- Dry through the weekend, precipitation chances return Sunday night into Monday and at times next week.

SHORT TERM /THROUGH TONIGHT/

Issued at 230 PM CDT Fri Aug 21 2026

A cold front is currently making its way across Iowa this afternoon and evening. In front of it, a field of diurnal cumulus has formed. There are low expectations with this cumulus field as far as precipitation chances go today. As far as the environment across Iowa goes, MLCAPE values are in the neighborhood 2500J/kg across central and eastern Iowa with little in the way of CIN. Shear in northwest Iowa is decent - around 30 kts - and guidance suggests weak forcing is available in the northwestern portion of the area. That said, dry air has been pushing its way into the state through the day and there is very little in the way of moisture return which limits the potential for convection. Similarly, across southern Iowa which has been outlined by a Marginal (Level 1 of 5) Risk for severe weather today, CAPE (around 2500J/kg) and shear (35-40kts) would indicate some amount of severe weather potential, but with dry air pushing in and very little in the way of forcing, the threat for severe weather looks highly conditional. Should the boundary provide enough forcing for an updraft to organize, there's still potential for it to produce large hail and damaging winds.

Otherwise, overnight precipitation chances diminish even further as the aforementioned dry air continues to be advected in from the north. This dry air is being advected by a high pressure system, which will sink into the area on Saturday. This high pressure indicates fair weather and clear skies for the weekend. Continued northwesterly flow means temperatures will remain just below normal. Keeping with this trend, skies will remain clear Saturday night and through part of Sunday before moisture builds back into western Iowa.

LONG TERM /SATURDAY THROUGH FRIDAY/

Issued at 230 PM CDT Fri Aug 21 2026

Iowa remains seated between a ridge centered over the Four Corners region and a trough over the Great Lakes. If either of these systems shift, that will change how far east or west moisture gets back into the area by Sunday night, which is when the next shortwave looks to move through, potentially bringing more precipitation chances into Sunday morning. At the moment, however, deterministic guidance is still struggling with the timing of this system. With this comes some degree of disagreement with placement, all of which will be better assessed in the coming days. This upper level pattern looks to remain rather stagnant, with the potential for additional shortwaves to move through the region next week.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 628 PM CDT Fri Aug 21 2026

Skies are clear for the most part across the state except for some lingering smoke aloft. This may continue into tomorrow but is not expected to be impactful. Some patchy fog development remains possible tonight, but given the extra breeze behind the front and dry air advection, seems unlikely at this point. VFR cumulus may develop at our southern terminals tomorrow afternoon but confidence is too low for inclusion at this time.

DMX WATCHES/WARNINGS/ADVISORIES

None.