textproduct: Des Moines

KEY MESSAGES

- Warm and slightly breezy today. Scattered showers and thunderstorms possible this evening into the overnight hours, mainly in northern Iowa. A few storms may be strong, especially early the evening, with gusty winds and hail being the main concerns.

- Showers and storms may linger in northern Iowa during the day monday (15-20% chance) then focus in northwest Iowa in the evening.

- Summertime pattern with highs in the 80s for the remainder of the week. Shower and storm chances for the southwest half, mainly occurring in the peak heating hours.

SHORT TERM /THROUGH MONDAY/

Issued at 305 AM CDT Sun May 24 2026

Relatively quiet conditions are in place over Iowa early this morning as weak high pressure sits overhead. Cloud cover has all but departed the area, with just a few lingering clouds over the western portions of the state that are quickly eroding. These clear skies and light winds will allow for temperatures to cool into upper 40s to low 50s this morning. However, these cooler temperatures will quickly turn warmer today, as a subtle mid-level wave over the plains works eastward, bringing south southwesterly low level flow and warmer air into Iowa. Highs today are expected to climb into the 80s under mostly clear skies. Increasing surface pressure gradients and a deeply mixed boundary layer will allow for slightly breezier conditions today, mainly over western Iowa, although winds will still only be around 15 mph with gusts to 25 mph. Altogether, today's weather will be quite pleasant for the Sunday of Memorial Day Weekend!

While conditions remain dry during the day today, we are still monitoring shower and thunderstorm potential for this evening into the overnight hours. The broad southwesterly flow through the low levels will allow for increased moisture return within a developing 850 mb jet. This jet will originate in the Texas/Oklahoma panhandles and extend all the way up into southwestern Minnesota, just clipping the northwest portions of Iowa. The moisture stream will also coincide with a destabilizing environment over eastern Nebraska and western Iowa through Sunday afternoon, introducing thunderstorm potential just to our west.

High resolution guidance has been fairly inconsistent with when and where this convective initiation will occur later today, likely due to the lack of any strong forcing mechanism. For our forecast area, most of guidance doesn't have anything occurring in Iowa until 00z at the earliest (7 pm CDT) and some not until the LLJ ramps up around 03 to 04z (10 to 11 pm). If any storms do develop around 00z, they could produce hail or gusty winds, mainly in western and northwestern Iowa where the best instability resides. By 03 to 04z, instability will be waning and any storms moving into or developing over our area will encounter a more stable environment, limiting the severe weather potential farther east. That said, the wild card tonight will be the rather robust 30 to 40 kt low level jet that will be pivoting into Iowa through the evening. This jet will fuel continued showers and storms over northern into central Iowa through the overnight hours. Storms will have less than 1000 J/kg of MUCAPE to work with overnight, so the severe risk will still be low, but evaporative cooling from the dry sub-cloud layer could still cause some locally enhanced winds beneath showers or storms. The storm prediction center has decided to trim the eastern edge of today's marginal risk (level 1 of 5) for severe weather, now only just clipping our far western fringes. Scattered showers and storms last into early Monday morning.

LONG TERM /MONDAY NIGHT THROUGH SATURDAY/

Issued at 1229 PM CDT Sat May 23 2026

Upper-level ridging will start its expansion on Monday in response to the blocking pattern, and the height contours will orient vertically west of here with time, pulling the best moisture axis away from the area. Remnant moisture from the night before will have stalled over northern Iowa, which may be enough to realize the instability that remains before peak heating. Have added in 20% PoPs to reflect this. Better consensus in rain and storms is presented in northwest Iowa in the evening and the LLJ takes over again. Should storms be present in northern Iowa at this point, weak flow will make them assume a slow, perhaps westerly motion.

For the week, Iowa will reside almost under center of the ridge in the omega block, favoring warm, summertime temperatures. The challenge will be the looming moisture axis in southwest Iowa and the trapped closed low ejecting almost due north from the ArkLaTex region. The other challenge is the later arrival of high pressure later this week. Eventually, when that gets here, dry air will dominate. Until we get there, temperatures in the 80s will be accompanied by showers and storms, mainly in peak heating hours. Highest confidence in storms will be across southern and southwest Iowa.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 622 AM CDT Sun May 24 2026

VFR conditions prevail today. Calm winds this morning become light to breezy out of the south southwest today. Scattered showers and thunderstorms develop this evening into Monday morning, mainly over northern Iowa. Have covered the most likely timeframe with PROB30 -SHRA groups, but thunder will be possible at times as well.

DMX WATCHES/WARNINGS/ADVISORIES

None.