textproduct: Des Moines

KEY MESSAGES

- Light showers south of I-80 ending through the morning. Cooler otherwise today with highs in the upper 50s to low 60s.

- Frost potential and near freezing conditions returns over north to north-central Iowa tonight and Wednesday night.

- Dry and cool Wednesday, followed by warming late week and into the start of the weekend, along with a few chances (20-40%) for showers and some storms.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 347 AM CDT Tue May 5 2026

Scattered rain showers continue to move very slowly east/northeast over the south central to southern portions of Iowa early this morning, which are the 850mb boundary that is into northern Missouri. Total rainfall so far with this activity has been minimal, with values over the forecast area up to a few tenths of an inch in some locations near the western I-80 corridor, while most areas that saw rain mostly reported values of a trace to few hundredths. As the boundary continues to drop south through the morning, this light shower activity will gradually depart the state just after sunrise, with minimal additional accumulations expected. Isolated and occasional gusty winds have also been occurring into this morning near these showers, with values up to 35-40 mph at times, but should continue to diminish over the next few hours with the departing feature. Temperatures continue to decrease as the cooler air continues to filter across the state, with northwest winds and temperatures in the upper 30s to 40s northwest, and in the low to mid 50s southeast. A large area of surface high pressure extending down into the Northern Plains currently will continue to drop southeast, moving through the Central Plains today. Dry and cooler conditions are expected through the remainder of today, with forecast highs reaching into the upper 50s to low 60s as winds remain northwesterly. An increase in mixing is expected to occur by late morning through the afternoon, leading to breezy conditions as gusts up to 20-25 mph are possible. The potential also exists for the development of elevated instability that would indicate cumulus development mainly over northern Iowa, while more widespread cloud cover is expected further south. Winds turn light this evening into Wednesday morning and remain northwesterly, with overnight lows expected to fall into the 30s to low 40s, warmest south. Temperatures in the low to mid 30s expected specifically over northern to north central Iowa are forecast at this time, though lingering clouds are suggested to some degree over portions of the affected areas, resulting in lower confidence on the formation of frost. Will be monitoring trends through the day, with related headlines still a possibility.

Dry and cooler conditions persist through Wednesday given the overall little change in synoptic pattern, as any rain chances are indicated to remain well west and south of the area. Highs in the mid to upper 50s are expected as northwesterly winds remain, turning breezy into the late morning to afternoon as boundary layer mixing occurs given the presence of low level dry air. Some limited moisture however in the mid-levels, along with the indication of elevated instability across the forecast area will likely lead to more widespread cumulus development, which is also supported by HREF guidance. Temperatures falling into the mid to upper 30s across central Iowa, with another potential for frost formation if the presence of at least some cloud cover overhead clears out overnight.

LONG TERM /THURSDAY THROUGH MONDAY/

Issued at 347 AM CDT Tue May 5 2026

Through Thursday morning, a shift to southwesterly flow will lead to a push of warmer air back into the region, resulting in increasing temperatures as highs are expected to top out in the mid to upper 60s. A weak shortwave passing southeast across the Great Lakes region is signaled per guidance later in the day, with developing rain showers mainly over far eastern Iowa into Wisconsin/Illinois, though limited moisture further west should keep conditions dry over central Iowa.

The upper level northwest flow pattern will persist at the end of the work week as the large gyre of low pressure remains over eastern Canada, while ridging builds further across the western CONUS. Another shortwave passing over Iowa and surface boundary is indicated within this pattern, suggesting more widespread but low chances (20-30%) for rain showers and even some storm activity. At this time, highest chances are indicated over east/southeast Iowa. Temperatures will remain on the warm side in the upper 60s to low 70s despite shifting surface winds northwesterly into the afternoon and through the evening. A stronger push of WAA into the weekend will lead to slightly warmer conditions, with highs Saturday through the 70s. A broader shortwave impulse passing though the region later Saturday into Sunday looks to hold a better potential for more widespread chances (20-40%) for showers and storms over Iowa, though exact details are not well known this far out in the forecast period, though details will be better known in the coming days.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 633 AM CDT Tue May 5 2026

Light rain near KOTM is expected to depart the area within the next hour or so, with dry conditions returning across the terminals through the rest of the day. VFR conditions are expected through the period, with mid to upper level clouds likely pass through over the next several hours. Winds out of the northwest will increase later this morning and into the afternoon, with gusts up to 15-20 knots before decreasing through the evening hours.

DMX WATCHES/WARNINGS/ADVISORIES

None.