textproduct: Des Moines

KEY MESSAGES

- Cool temperatures with highs in the 60s today through Friday.

- Showers and a few thunderstorms likely (70%) Thursday night though Friday. Highest rainfall amounts (up to an inch) in southwest Iowa.

- Warming trend expected for the remainder of the forecast with active weather continuing. Thunderstorm chances increase next week.

SHORT TERM /THROUGH FRIDAY/

Issued at 146 PM CDT Wed May 20 2026

A few high clouds reached western Iowa today. This was due to troughing over the Rockies generating lift over the High Plains. More to the east, a slow-moving high pressure kept cool, fair weather in place over Iowa. This feature also will delay the arrival of low-level moisture until late in the day Thursday. The trough will break free and pivot into the region at this point, bringing rain chances Thursday night and most of Friday. There could be a rumble of thunder accompanying the rain, but thunderstorms activity has some limiting factors: 1) A southern stream counterpart to the main trough will advance first, negatively tilting over Missouri. It's location favors the moisture axis being shoved east into the Ohio River Valley region, keeping higher PWATs out of Iowa. 2) Weak flow over the desert southwest beforehand, so the EML is largely left behind, lowering lapse rates and CAPE. For rainfall amounts, southwest Iowa will see the most rain as it will feel the impacts from both shortwave features. They could see rainfall amounts over an inch, but those amounts will be spread out over time. A slowed, deeper solution (NAM solution) of the second wave would give more time for instability and moisture to advect in. This would result in more thunderstorm activity and higher rainfall amounts.

LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/

Issued at 146 PM CDT Wed May 20 2026

The second wave will lift into Minnesota and drag a cold front along with it. Some lingering showers will be possible in northern Iowa close to its influence, but the front will work to erode moisture and delay warmth until Sunday. There will be scattered showers on Sunday as a shortwave trough ejects across the state, at the very minimum some cloud cover. As mentioned in the previous discussion, an upper-level low in the southern CONUS will get trapped within the ridge early next week. Behind it will be deepening troughing, featuring two closed features, one in the PNW and one in southern California. The pattern favors warming temperatures with the advection of the thermal ridge, but that first trapped feature leaves some question marks early on. The solution this period continues to favor a due-north ejection into Iowa as early as Tuesday night. Temperatures increase and precipitation chances broaden in the second half of next week. Warm, active weather is favored with the western CONUS troughing and the next best chance of precipitation will arrive when the southern feature is flung into the Plains by its northern counterpart. Regional ridging persists into next weekend.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 624 PM CDT Wed May 20 2026

VFR conditions ongoing and expected to continue through the TAF period. Mid-level clouds between roughly 05kft and 10kft expected through much of the period with winds out of the northeast to start, becoming out of the east into Thursday morning and increasing, but generally staying around 10-15 knots. Rain chances increase later Thursday night but after this TAF period for TAF sites.

DMX WATCHES/WARNINGS/ADVISORIES

None.