textproduct: Des Moines

KEY MESSAGES

- Around 15% chance for isolated and short lived showers and storms in the northern part of the state this afternoon

- Overall dry pattern into the weekend, with consistent highs in the mid 80s.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 225 PM CDT Wed May 27 2026

An anomalously mundane weather pattern continues across the state today as a persistent omega block centers over Iowa. Aside from the typical omega block pattern (longwaves in the west and east, ridge in the central US), a shortwave embedded in the sub- tropical jet over Texas is visible on water vapor imagery. For Iowa specifically, clear skies are putting temperatures on track for the upper 80s later this afternoon. Moisture is mixed out for the most part, except for northern Iowa where about 1000 J/kg of SBCAPE is in place. This combined with very weak shear may allow for a few isolated and short lived thunderstorms in the northern part of the state over the next few hours. Dry low levels will likely keep QPF low from these storms.

Through the overnight and Thursday morning, the Texas shortwave will attempt to pivot around the longwave towards Iowa, but will be shunted to the south and west by the 500mb ridge across the north- central US. The moisture axis being dragged along with the shortwave will likely remain just west of the CWA Thursday into the weekend. At the same time, high pressure over the Great Lakes will strengthen. Subsident surface flow out of the east and off of the Great Lakes will bring in cooler, drier air through the day Thursday. Still, the 850mb high will be centered over Iowa, and warm 850 temps will still be in place. Those two things considered, highs Thursday may be warm but are expected to be slightly cooler than today in the low to mid 80s.

LONG TERM /FRIDAY THROUGH TUESDAY/

Issued at 225 PM CDT Wed May 27 2026

Remarkably similar mid-80s highs are expected through the end of the period, though confidence decreases after Monday. The moisture axis mentioned above will likely remain west of our area until Sunday and keep precip chances low, though some light shower chances exist Friday/Saturday in southwest Iowa depending on upstream mixing and convective evolution. On Sunday, a shortwave embedded within the western longwave will pivot across the high plains. It is likely this will be too far west to create any meaningful shear, but may be enough to bring the moisture axis further into Iowa. GEFS SBCAPE probabilities increase significantly Sunday and beyond, and more QPF outliers show up in the NBM members Sunday night and afterwards (though an overall dry pattern will likely still dominate). Ensembles suggest the omega block pattern will begin to break down early next week, and the exact evolution of how the ridge breaks down and the longwave finally ejects will determine whether our hazards for next week are garden variety single cell thunderstorms or stronger, more organized storms.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1124 AM CDT Wed May 27 2026

VFR conditions will prevail at all terminals through the period. Light and variable winds will persist today and tonight. Tomorrow morning, winds will take on a more easterly direction at around 10kts. There is a low chance (10-15%) for a shower or thunderstorm to impact KFOD or KMCW this afternoon. Due to low confidence and low probability, this was not mentioned in the TAFs but will be monitored for the 00z issuance.

DMX WATCHES/WARNINGS/ADVISORIES

None.