textproduct: Des Moines

KEY MESSAGES

- A few thunderstorms remain possible across northern Iowa, and briefly in far southeast Iowa, this afternoon. There is a low threat of severe weather in the form of hail and strong winds.

- Aside from any thunderstorms, increasing west northwest winds will gust to near 45 MPH in northwestern Iowa this afternoon to evening, and gust to 35-40 MPH farther south and east. A Wind Advisory remains in effect for portions of northwestern Iowa through the evening.

- Generally quieter weather is forecast Thursday and Friday, though spotty showers or storms will still be possible at times (10-20% chance). More substantial rain and thunderstorm chances then return late Saturday into Sunday.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 121 PM CDT Wed Jun 17 2026

In wake of this morning's MCS things have been relatively stable and quiet across the area today, however, more showers and storms are beginning to form just north and south of Iowa at this time. As the surface low passes just to our north across southern Minnesota and into western Wisconsin this afternoon, it is trailing a sharp trough which is moving across our area early this afternoon, Winds are quickly shifting from SW to WNW as the boundary moves through, and temperatures are increasing due to downsloping and clearing skies/increasing insolation. Close to the surface high, regional radar depicts convective initiation near the IA/MN border and up toward the Twin Cities, and there is a corridor of enhanced 0-3 KM CAPE in that area. However, it remains to be seen whether any strong storms will be able to build south as far as our area, around Worth and Cerro Gordo counties, before the wind shift sweeps through and ends any surface-based threat. The window of opportunity up there is thus very brief. That being said, additional showers and storms are expected to bubble up behind the wind shift this afternoon and evening, and may affect our northern counties through about sunset. Behind the wind shift the flow is unidirectional with long, straight hodographs, and near-surface-based instability crashes rapidly. However, modest CAA aloft and pressure rises are supporting strong environmental winds with surface gusts to 30-35 KT, so if any elevated storms are able to mix even stronger winds aloft down to the surface, there may be a sneaky threat for spotty severe straight-line winds through the evening.

Farther south, the synoptic boundary reinforced by a cold pool from morning convection lies near the IA/MO border, with showers/storms percolating along it just barely south of our area at this time. The boundary is expected to be a focus for explosive convection later this afternoon/evening, however, that threat will remain southeast of us in Missouri and Illinois. A few storms may be able to just clip our southeastern corner, down around Appanoose/Davis counties, on the 925-850 MB boundary this afternoon, however, just as in our northeast the window of opportunity for severe weather will be limited and brief.

Once any evening showers or storms clear out of our area around/after sunset, tonight will be generally quiet as today's low pressure system and associated boundary continue to move away to the east. However, late in the night and into Thursday, a 500 MB shortwave impulse will move overhead and provide some weak lift and instability that may trigger additional showers/storms. Coverage and intensity of any such convection should be minimal and have included only patches of slight chance (20%) PoPs accordingly. While it is difficult to determine which areas will see rain and which will not, the most likely region would be northern Iowa closer to the passing shortwave and have limited the low POPs to that area. Some high- res models are painting a strip of light QPF across far southern Iowa around Thursday morning, which is associated with a narrow band of 650-600 MB frontogenetical forcing moving near the Missouri border. However, forecast soundings indicate only fleeting moisture availability with dry air below this layer, and have kept PoPs low enough (10%) to preclude rain mention at this time. Behind the shortwave impulse a brief period of ridging will build in Thursday night resulting in quiet weather lingering into Friday.

LONG TERM /FRIDAY THROUGH TUESDAY/

Issued at 121 PM CDT Wed Jun 17 2026

From Friday through the weekend, Iowa will lie beneath west northwesterly steering flow aloft, though which two 500 MB troughs will move overhead. The first of these will come Friday, with the associated vorticity maximum moving by just to our north over Minnesota. Surface high pressure in place early in the day will gradually retreat eastward, while an inverted trough develops along the High Plains and extends northeastward to roughly near the Iowa/Minnesota border. In the afternoon and evening sufficient destabilization should occur beneath the broad forcing for ascent associated with the passing 500 MB trough to allow for the possibility of convective initiation. However, low-level flow/shear profiles are generally unimpressive and instability should remain limited with SBCAPE <500 J/KG near the surface boundary in northern Iowa. The most likely outcome in this scenario is isolated showers and thunderstorms with a low severe weather potential.

A deeper 500 MB trough will cross the region from late Saturday into Sunday, bringing renewed rain chances to at least parts of Iowa. However, longer-range models remain divided on the track and evolution of this system, with the GFS initiating convection farther south in Nebraska and more rigorously than the ECMWF, resulting in an apparent MCS affecting parts of Kansas, Missouri, and perhaps southern Iowa. Meanwhile the ECMWF has a broader and more northward solution depicting widespread rain across Iowa. For now will maintain the areawide 60-80% PoPs initiated by the NBM and monitor model trends in the coming days. Early next week there are indications that another trough may cross the region, but at this range details are even less clear.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1229 PM CDT Wed Jun 17 2026

Low IFR ceilings will linger at ALO/MCW for about another hour before pushing out this afternoon; otherwise, prevailing VFR conditions are forecast through this evening. A few showers or thunderstorms will be possible at MCW/ALO between about 20Z and 23Z and have included PROB30 groups at those terminals accordingly. Low clouds are also expected to redevelop in northeastern Iowa overnight into early Thursday, with at least intermittent MVFR ceilings possible at MCW/ALO once again. Meanwhile, winds will shift through southwest to west northwest early this afternoon and increase significantly, with 20+ KT crosswinds possible on some runways until winds gradually subside after sunset.

DMX WATCHES/WARNINGS/ADVISORIES

Wind Advisory until 9 PM CDT this evening for IAZ004-015-023- 033-034-044.