Iowa Weather Forecast Friday: Severe Storm Risk Tonight

A quiet start to the afternoon is expected across much of Iowa after overnight showers and thunderstorms moved through portions of the state. While a lull in precipitation is anticipated through much of the day, we are closely monitoring conditions that could support another round of strong to severe thunderstorms later this evening and tonight.

One of the biggest forecast challenges today is the extensive cloud cover that developed behind this morning’s storms. The amount of clearing that occurs this afternoon will play a significant role in determining how unstable the atmosphere becomes ahead of potential storm development.

Despite the cloud cover, warm and humid conditions are expected to return with temperatures climbing into the 80s and dew points rising into the upper 60s and lower 70s. If enough sunshine develops, atmospheric instability could increase dramatically by late afternoon and evening.

Greatest Severe Weather Risk South of Interstate 80

The Storm Prediction Center continues to highlight much of southern Iowa in a Slight Risk (Level 2 of 5) for severe thunderstorms.

A frontal boundary draped across the region will serve as the focus for thunderstorm development later today. Forecast models continue to disagree on the exact location of this boundary, creating uncertainty regarding where storms will initially develop.

Current trends suggest the highest probability for severe weather will be across southern Iowa, particularly near and south of Interstate 80, with the greatest risk potentially closer to the Iowa-Missouri border.

Some forecast guidance has attempted to bring storms farther north toward Highway 30, but this currently appears less likely.

Large Hail and Damaging Winds Primary Threats

If thunderstorms develop this evening, the environment will be capable of supporting severe weather.

The primary threats include:

• Large hail
• Damaging wind gusts
• Locally heavy rainfall

A tornado cannot be ruled out, especially near the frontal boundary where low-level wind shear may be locally enhanced. However, the overall tornado threat currently appears lower than the hail and wind threat.

Flash Flooding Remains a Concern

In addition to the severe weather threat, localized flooding will remain possible tonight.

The atmosphere will continue to contain abundant moisture. Storms that repeatedly move over the same locations could produce heavy rainfall in a short period of time.

This concern is heightened because many areas have already received significant rainfall over the past 24 hours. Additional heavy rain could lead to localized flash flooding, especially in low-lying and poor drainage areas.

The Weather Prediction Center has highlighted portions of the region in a Slight Risk (Level 2 of 4) for excessive rainfall, as pictured above.

Area rivers and streams are also being monitored closely as water levels continue to rise from recent rainfall. Minor flooding cannot be ruled out in some locations if additional heavy rain develops tonight.

Timing and Forecast Confidence

The most likely time for storm development appears to be between 6 PM and Midnight, although some storms could persist later into the overnight hours.

There remains moderate uncertainty regarding exactly where storms will form and how widespread they become. Some forecast models show robust thunderstorm development across southern Iowa this evening, while others are less aggressive with storm initiation.

Even with that uncertainty, any storm that develops will have the potential to become severe.

Residents across southern Iowa should monitor forecasts closely throughout the day and have multiple ways to receive warnings this evening and tonight.

Stay Updated Throughout the Day

Forecast details may continue to change throughout the day as we monitor cloud cover, boundary placement, and storm development trends. Be sure to follow the Iowa Storm Chasing Network (ISCN) on Facebook for forecast updates, live weather coverage, and any watches or warnings that may be issued later today. You can also check back frequently at IowaWeather.com for the latest forecast discussions and severe weather updates. If you haven’t already, make sure the ISCN Weather app is installed on your phone so you can receive important weather information and stay informed wherever you are. With the potential for severe weather and localized flooding tonight, having multiple ways to receive alerts is strongly encouraged.