textproduct: Des Moines

KEY MESSAGES

- Strong to severe storms early Wednesday morning. Large hail and damaging wind gusts are the main hazards.

- Severe storms redevelop Wednesday afternoon across eastern half of Iowa. Very large hail, damaging winds and a few tornadoes are possible.

- Strong winds behind the storms on Wednesday gusting 35-40 mph at times.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 241 PM CDT Tue Jun 16 2026

Breezy northwest winds this afternoon thanks to an enhanced pressure gradient across central to eastern Iowa and dry air allowing for deeper mixing. Upstream water vapor imagery shows the beginnings of development across the northern plans that will drop across the midwest early tomorrow morning. Overnight a strong 65+ kt low level jet will set across the plains with the nose reaching far northwestern Iowa. While showers may swing across the area late this evening, the low level jet looks to ramp up around 06z and intensification will occur early Wednesday morning on the nose of the jet in northern Iowa the sliding southeast as the jet is shunted into southeast Iowa. The upper level jet is also very strong (125+ kts) and perpendicular to the LLJ, creating an area of enhanced lift. Expect that strengthening storms will develop across northern Iowa around 10z as the strong LLJ brings strong moisture and theta e advection into the area. Large, looping hodographs have unheard of levels of SRH, mainly owed to the very high shear. When accounting for the effective layer inflow that the storms may actually ingest, 250-300 m2/s2 is likely still available and more than enough for strongly rotating updrafts. By 10z mid level lapse rates are at 8 C/km, 0-6 km shear is 50-60 kts, and a pool of 1500+ J/kg MUCAPE reaches to northern Iowa. Storms are expected to move along this gradient into eastern and southeast Iowa through the morning hours. All of the ingredients are in place for strong rotating updrafts sustaining large hail growth. While storms are largely elevated, wind is also a concern, especially with dry sub-cloud layers that may have wet hail falling through, enhancing the evaporative cooling and pulling strong gusts to the surface. As such, a wind driven hail threat is possible. This activity should push east of the area by around 15z.

After a midday lull, redevelopment is expected on the boundary in southeast Iowa in the afternoon in the 18-20z window. This will quickly race to the east and clear the area by 00z. The environment south is deeply unstable with 3000+ J/kg MUCAPE and 60 kts of 0-6 km shear. Hodographs are straight which may reduce, but not completely eliminate, the tornado threat in Iowa. The other area to watch in the afternoon is northern Iowa with a surface low skimming southern Minnesota and creating a tornado risk in the vicinity of the triple point. The environment is less unstable there, but may still result in a brief window for sever storms in northeast Iowa.

Outside of the convective risk, Wednesday will also be quite breezy. Winds in southern Iowa will gust 35+ mph behind the morning convection. Then in the afternoon to early evening northern Iowa gets breezy with 35-40 mph gusts behind the storms. In both cases the area for strongest gusts is outside of the area (south and west in the morning or west in the afternoon), so have not issued a wind advisory at this time.

LONG TERM /THURSDAY THROUGH TUESDAY/

Issued at 241 PM CDT Tue Jun 16 2026

Thursday and Friday will be mild and quiet with highs in the upper 70s to low 80s. A quick moving, weak embedded shortwave may move across the area on Thursday and bring a quick shot for precipitation, otherwise conditions will remain dry. Attention will then turn to the deepening low pressure that will move into the area late Saturday into Sunday. This is expected to bring another round of storms, some severe, to Iowa. Details on this system will be better determined in the days ahead.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 641 PM CDT Tue Jun 16 2026

VFR TAFs are in place across all sites with the 00Z issuance. Northwesterly winds will persist over the next couple of hours before shifting to the south ahead of an approaching boundary. As a low-level jet starts to ramp up overnight, LLWS is forecast to develop around 09Z with all sites experiencing LLWS through 12Z before turbulent mixing negates LLWS. Showers and thunderstorms are expected to develop along the boundary through the overnight and dive southeast across northern Iowa. KFOD and KMCW will start to see an increase in shower and storm chances mainly after 06Z but becoming more widespread around 09Z. KALO will also start to see increasing shower and storm chances after 09Z. KDSM and KOTM are largely on the fringe of the better precipitation chances but chances for shower and storms increase gradually toward 14Z. Overnight/morning convection is forecast to wane after 18Z with a lull in activity before redevelopment occurs late in the forecast period. However, strong winds are progged to persist through the period. Sustained winds from 15 to 20 knots with wind gusts ranging between 25 to 30 knots are likely especially at KFOD, KMCW, KDSM and KOTM after 15Z and persisting through the remainder of the TAF period.

DMX WATCHES/WARNINGS/ADVISORIES

None.