Severe Weather Returns to Iowa: Multiple Rounds of Storms Possible Through Friday

After several days of dangerous heat and humidity, Iowa will remain in an active weather pattern through at least Friday. While not everyone will see severe weather each day, several rounds of thunderstorms are expected to develop during the late afternoon, evening, and overnight hours. Some of these storms could become severe, producing damaging winds, large hail, isolated tornadoes, and locally heavy rainfall.

The greatest risk each day will generally be across northern and western Iowa, though storms could eventually impact other parts of the state depending on where storm complexes track.

Tuesday Night: Damaging Wind Threat Develops Across Northern Iowa

The first round of storms is expected to develop late Tuesday evening into the overnight hours as a strengthening low-level jet interacts with a very warm and humid air mass across Iowa.

Most of central and southern Iowa should remain dry through much of the evening. However, after midnight, thunderstorms are expected to increase across western and northern Iowa before moving east toward sunrise.

The atmosphere will contain plenty of instability, but wind shear will only be modest. Because of this, storms are expected to organize into clusters rather than long-lived supercells. The biggest concern will be damaging straight-line winds. Forecast soundings also show a significant amount of dry air in the middle levels of the atmosphere, which can enhance downdrafts and increase the potential for severe wind gusts.

Large hail will also be possible, although it appears to be a secondary threat compared to damaging winds.

Tuesday Night Hazards

• Timing: Midnight through 7 AM Wednesday
• Greatest Risk: Northern and western Iowa
• Primary Threat: Damaging wind gusts of 60-75 mph
• Secondary Threat: Quarter-sized hail or slightly larger
• Tornado Risk: Very low
• Heavy Rain: Localized flooding possible in poor drainage areas

Wednesday: Another Round of Severe Storms Looks More Concerning

Wednesday will likely begin with leftover storms moving out of northern Iowa during the morning. After that, another hot and humid day is expected, with temperatures climbing into the 90s and heat index values once again approaching or exceeding 100 degrees across much of the state.

Attention then turns to another round of thunderstorms expected to develop late Wednesday afternoon and Wednesday evening near a warm front positioned across northern Iowa or southern Minnesota.

Unlike Tuesday night, the atmosphere Wednesday evening should have stronger wind shear while maintaining extreme instability. This combination could allow storms to become supercells before eventually merging into larger storm clusters.

Damaging winds once again appear to be the primary threat, but the environment will also support large hail and the possibility of a few tornadoes, especially if storms remain isolated while moving along the warm front.

Wednesday Hazards

• Timing: 5 PM Wednesday through Midnight
• Greatest Risk: Northern Iowa, with storms potentially moving farther south overnight
• Primary Threat: Damaging winds up to 70-80 mph
• Large Hail: Up to golf ball size possible
• Tornado Risk: Low, but not zero
• Heavy Rain: Localized flash flooding possible where storms repeatedly move over the same areas

Thursday: Yet Another Opportunity for Severe Storms

The overall weather pattern changes very little on Thursday. Iowa will remain on the northern edge of a strong ridge of high pressure, allowing disturbances to continue tracking through the Upper Midwest.

Storm chances will once again increase during the late afternoon and evening, especially across northern and western Iowa.

Forecast models suggest another environment capable of producing supercells initially before storms organize into larger complexes during the evening. If this occurs, damaging winds would once again become the primary concern, although all severe weather hazards remain possible.

Exactly where storms develop will depend heavily on where Wednesday night’s storms leave behind outflow boundaries. Those boundaries often become the focus for the next day’s severe weather.

Thursday Hazards

• Timing: Late afternoon through overnight
• Greatest Risk: Northern and western Iowa
• Primary Threat: Damaging straight-line winds
• Secondary Threats: Large hail, isolated tornadoes, heavy rainfall

Heat Continues Alongside the Storm Threat

Even with daily storm chances, dangerous heat will continue across Iowa through at least Thursday and possibly into Independence Day.

Afternoon temperatures will climb into the lower 90s, while dew points remain in the 70s. Heat index values between 95 and 105 degrees will continue across much of the state, especially central and southern Iowa.

If you plan to spend time outdoors, be sure to:

• Drink plenty of water.
• Take frequent breaks in the shade or air conditioning.
• Avoid strenuous activity during the hottest part of the afternoon.
• Never leave children or pets inside parked vehicles.

Looking Ahead to the Holiday Weekend

The active weather pattern is expected to continue into the Fourth of July weekend. While temperatures may ease slightly compared to earlier this week, Iowa will remain warm and humid with periodic chances for thunderstorms.

Forecast confidence decreases beyond Friday because each round of thunderstorms will influence where the next round develops. That means exact timing and locations of future severe weather will become clearer over the next couple of days.

The Main Takeaway

Iowa is entering a stretch of multiple opportunities for severe thunderstorms from Tuesday night through at least Friday. Not everyone will see severe weather every day, but northern and western Iowa have the highest chance of experiencing repeated rounds of strong to severe storms.

The primary threat throughout the week will be damaging straight-line winds, with large hail, isolated tornadoes, and localized flash flooding also possible depending on how each round of storms develops.

Residents across Iowa should remain weather aware each afternoon and evening, especially if you have outdoor plans. Make sure you have multiple ways to receive warnings, including the ISCN Weather App, as forecast details and storm locations will continue to be refined over the coming days.