textproduct: Des Moines

KEY MESSAGES

- Much of central Iowa dry today with highs a few degrees either side of 80.

- Chances for scattered showers and a few storms spread into central Iowa tonight into Saturday up to around 50%. Not an all day washout. Severe weather is not forecast, but lightning a concern for those with outdoor plans. Highly localized rainfall amounts up to 2 inches possible on Saturday, but also highly uncertain if and where this may occur. In addition, winds will be breezy on Saturday.

- Seasonal temperatures through this weekend, then a bit above normal into next week. Occasional shower and storms chances persist through late this weekend into next week with low chances for severe weather or widespread heavy rainfall.

SHORT TERM /THROUGH SATURDAY/

Issued at 155 AM CDT Fri May 29 2026

Early morning GOES-East upper level water vapor imagery shows an amplified, stagnant omega blocking pattern in place with troughing over the western CONUS and also from the Great Lakes into the Northeastern US with a ridge from the Deep South into the south central Canadian prairies. Lifting northeastward ahead of the western CONUS trough, there is an elongated area of shortwave energy. The aforementioned GOES imagery shows a good plume of Gulf moisture with this energy, which is reflected in objective RAP analysis at 925mb and 850mb. This moisture has already spread into southwestern and western Iowa with higher content over Kansas, but that will be lifting into the state later today into Saturday as the shortwave energy moves toward the state. With the forecasted increase in cloud cover, did taper back high temperatures a degree or two today from the initial National Blend of Models (NBM) closer to the 50th percentile of available guidance. This kept highs in the middle and upper 70s in southwest Iowa to the low 80s in eastern Iowa. Chances for any rain today are higher west of our forecast area in western Iowa and points west closer to the approaching shortwave energy and moisture plume. Forecast soundings show that dry air, especially in the mid-levels and lesser so in the low levels, will keep conditions dry farther into central and certainly eastern Iowa. Instability is quite limited and shear is almost non- existent so much of this will be rain showers with intermittent rumbles of thunder at best.

As we move into tonight and Saturday, the shortwave energy lifts over the state with forecast soundings showing the saturating effects of the arrival of the plume of moisture with precipitable water values up to around 1.5 inches. The forcing and moisture will lead to more widespread chances for showers and storms spreading from western into central Iowa during this time frame. However, examining convective allowing model (CAM) guidance's reflectivity fields shows that this will not be a washout for any given location with spotty to scattered activity. Instability up to around 1000 J/kg may reach our far western or southwestern forecast area with higher instability farther west and weak instability perhaps as far northeast as our northeastern forecast area. The highest shear of around 25 knots will be focused over southwest Iowa. The lack of shear and saturated profiles point to little if any severe weather potential, which aligns with the latest SPC day 2 outlook, but lightning is still possible and could interrupt outdoor plans as a storm moves through a given location. Warm cloud depths are seasonally high and with weak 850-300mb flow, storms will be slow moving. Latest HREF localized probability matched mean (LPMM) shows a few bullseyes of 1.5 to 2 inches of rainfall with NBM PMM showing up to an inch. The cloud cover will keep highs a bit lower for much of the area Saturday with highs in the upper 70s. In addition, winds from the southeast will turn breezy by mid to late morning through the afternoon hours. BUFKIT soundings show winds within the limited mixing depth still supportive of gusts of 20 to 25 mph over central Iowa and may top 30 mph up towards Estherville. While CAMs are not showing this at the moment, a shower or storm could entrain these types of winds to the surface as well.

LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/

Issued at 133 PM CDT Thu May 28 2026

Uncertainty in the long range is high as the trough in the west is trying to eject, shortwaves around the western fringe of the eastern Canada longwave trough are pivoting south, and remnant central US shortwave will dissipate or merge with the next shortwave. Regardless, as the western trough attempts to eject, it looks likely southerly flow will bring a more robust warm sector into or near Iowa. Latest GEFS guidance brings moderate CAPE into Iowa by Sunday and Monday. On a large scale, period of thunderstorms look possible in the long term. EPS/GEFS position Iowa atop a decaying ridge and a shortwave off the the west, making weak to moderate shear possible. Any severe weather through the period will become highly contingent on mesoscale details, particularly convective evolution closer to the shortwave further west, and require more model certainty to untangle.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 621 AM CDT Fri May 29 2026

VFR conditions to prevail through the end of this TAF period. As we progress through today, clouds are expected to increase. Clouds heights will fall below 10,000 ft as we head into early Saturday morning. Rain showers are expected to increase around 6z and will be spotty through the end of this TAF period. Due to medium confidence, prob30 groups were introduced at OTM, FOD,and DSM to represent the rain chances.

DMX WATCHES/WARNINGS/ADVISORIES

None.