textproduct: Des Moines

KEY MESSAGES

- Spotty showers possible late this morning through the afternoon.

- Frost Advisory issued across forecast area for Saturday morning, given widespread expected temperatures in the 30s, clear skies and very light winds.

- Low potential (20-30%) for storms in southeast Iowa Sunday evening, a few which could be strong.

SHORT TERM /THROUGH SATURDAY NIGHT/

Issued at 343 AM CDT Fri May 1 2026

Satellite imagery early this morning shows patchy mid-level cloud cover tracking southeastward across Iowa, given the presence of mid level moisture overhead. The midlevel flow pattern features a strong area of 500mb low pressure that is centered just north of the Great Lakes region, and broad ridging occurring over the northwestern CONUS. This setup has allowed for Iowa to be in a northwest flow pattern, which is not expected to really change anytime soon. Have been monitoring temperatures closely this morning, with values remaining overall steady in the upper 30s to low 40s. Regarding previous discussions of potential frost this morning, the aforementioned cloud cover is helping to mitigate efficient radiational cooling, with these patchy clouds expected to continue keeping temperatures right about where they are now through the remainder of the overnight hours and through sunrise. While a few isolated areas mainly over southwest Iowa could see brief mid 30 degree values, the potential for even isolated frost is quite low, which has led to no headline issuance for this morning. Beyond sunrise, will see temperatures warm into the mid to upper 50s, coolest north.

The expectation remains for the mid-level shortwave passing over Iowa through the day, and the development of elevated but weak instability with diurnal heating by late morning through the afternoon, to result in cumulus development across Iowa and the potential for some very light rain showers. Model soundings do show a deep layer of very dry air low in the lowest 1-2 km though, which will likely allow for difficulty in elevated hydrometeors to make it to the ground. Spotty sprinkles to isolated light showers at best are possible (20-30%), with a few rumbles of thunder at most not out of the question. Conditions will dry for all areas tonight, with an area of surface high pressure sliding southward across eastern Nebraska and Kansas, extending into Iowa. Skies becoming clear across the state, along with winds turning very light and even calm in some areas will allow for efficient and widespread radiational cooling to occur, sending temperatures down through the 30s, coolest over northern Iowa where values around freezing are most likely. With increasing confidence of these temperatures occurring and the resulting potential for areas of frost to form into Saturday morning, have issued a Frost Advisory across the entire forecast area.

The aforementioned high pressure area departs through Saturday, though conditions will remain dry, featuring shifting winds becoming westerly that will allow for temperatures to improve nicely through the day, maxing out in the low to mid 60s by the afternoon, warmest over western Iowa.

LONG TERM /SUNDAY THROUGH THURSDAY/

Issued at 343 AM CDT Fri May 1 2026

Little change in the upper flow pattern by Sunday, though another shortwave passage through Sunday morning is signaling the next chance for light rain over the area. As a boundary passes through the state, model guidance indicates better potential for the development of rain late Sunday into Monday morning, though mainly over northern Missouri extending into parts of southern Iowa. Despite notable forcing in southern Iowa per model soundings, low level moisture is rather limited. If better saturation occurs though, cannot rule out the development of some strong elevated storms, with instability values up to 500 J/kg and steep mid-level lapse rates around 8 C/km. A Marginal Risk of isolated severe storms has been included over far southeast Iowa per SPC due to this potential, so something to certainly monitor over the coming days.

The start of the next work week looks dry to start, with low level southwest flow at least through Monday morning allowing for warmer temperatures as highs are expected through the 70s. However, a stronger cold front is expected to drop across the area and bring the potential for showers and storms mainly over eastern and southern Iowa into the evening, where better saturation is located. This boundary sags further south out of the state by Tuesday, with any additional chances for rain generally into Missouri per latest long range guidance. Cooler temperatures are expected following the frontal passage, with highs Tuesday back into the 50s.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 625 AM CDT Fri May 1 2026

Patchy mid level clouds will continue to pass southeastward across the state this morning, followed by the development of cumulus across much of the state into the afternoon. VFR conditions are largely expected to continue, with lowest ceilings hovering just above MVFR during the afternoon that will be monitored. There is a low chance for a few isolated showers this afternoon, with mentions mainly included at KOTM and KALO but could occur further north and west. However, confidence is low on occurrence (10-20%), so have left out of this issuance in those areas. Winds out will shift northerly later this morning and especially afternoon, with gusts up to 15-20 mph.

DMX WATCHES/WARNINGS/ADVISORIES

Frost Advisory from 1 AM to 8 AM CDT Saturday for IAZ004>007- 015>017-023>028-033>039-044>050-057>062-070>075-081>086- 092>097.