Iowa Weather Alert: Severe Storms Possible Saturday Across Central & Southern Iowa

A severe weather threat is expected to develop across portions of Iowa Saturday afternoon through early Sunday morning as warm, humid air surges northward into the state ahead of a strengthening Plains storm system.

The Storm Prediction Center has placed much of Iowa — especially areas along and south of Highway 20 to the Iowa/Missouri border — under a Slight Risk (Level 2 of 5) for severe thunderstorms. The greatest concern will be during the late afternoon and evening hours, though additional storms may continue overnight.

Storms Could Develop By Mid to Late Afternoon

The atmosphere is expected to become increasingly unstable Saturday afternoon as temperatures rise into the upper 80s and lower 90s across parts of Iowa. At the same time, a boundary draped somewhere across central to southern Iowa may serve as the focus for thunderstorm development.

There remains some uncertainty on exactly where storms will first form, but current forecast guidance suggests initial development could begin after 3 to 4 PM.

Once storms develop, conditions will support rapid intensification. The atmosphere is expected to contain strong instability, steep lapse rates, and favorable wind shear — ingredients that can support organized severe thunderstorms and supercells.

Large Hail, Damaging Winds & Tornadoes Possible

The first storms that develop Saturday afternoon and evening may remain isolated for a time before eventually merging into clusters or lines later at night.

These isolated storms will have the greatest chance to become rotating supercells capable of producing:

• Large hail
• Damaging wind gusts
• Isolated tornadoes

Forecast soundings show enough low-level wind shear to support rotating updrafts, meaning a tornado threat will exist with any discrete storms that form before storms begin to merge together.

Large hail may also become significant in the strongest storms due to steep mid-level lapse rates and strong instability in place across the region.

Heavy Rainfall & Localized Flooding Concerns

In addition to the severe weather threat, thunderstorms may produce pockets of heavy rainfall Saturday evening into the overnight hours.

Repeated storms moving over the same areas could lead to rainfall totals of 2 to 3 inches in localized areas, with isolated higher totals possible where storms train repeatedly.

While much of Iowa has experienced relatively dry conditions recently, localized flooding could still develop in low-lying or urban areas if heavier rainfall rates occur over a short period of time.

Overnight Storm Complex Expected

A development of a larger storm complex is expected to organize across southwest Nebraska into northwest Kansas Saturday evening.

This complex of storms is forecast to track eastward overnight, potentially entering western Iowa after 2 AM Sunday morning.

Although storms may gradually weaken as they move east, damaging winds and heavy rainfall could still accompany this overnight activity as it tracks across portions of Iowa into Sunday morning.

Stay Weather Aware

With multiple rounds of thunderstorms possible and several severe weather hazards on the table, Iowans are encouraged to remain weather aware Saturday and Saturday night.

Be sure you have multiple ways to receive watches and warnings, especially overnight when storms may continue moving through the state while many people are asleep.

The Iowa Storm Chasing Network will continue monitoring trends closely and providing updates throughout the day and night across IowaWeather.com, the ISCN Weather app, and our social media platforms.