Iowa could see its most widespread rainfall in several weeks late this week as multiple rounds of showers and thunderstorms move through the state.
The Weather Prediction Center has highlighted a corridor extending from northeast Kansas through Iowa and into northern Michigan as an area where heavy rainfall may occur on Friday. While widespread flooding is not currently anticipated, some thunderstorms could produce locally heavy rainfall and lead to isolated flooding concerns where storms repeatedly move over the same locations.
Why The Rainfall Potential Is Increasing
A more active weather pattern will develop across the Midwest beginning Thursday as moisture streams northward from the Gulf and interacts with a series of disturbances moving through the upper-level flow.
Forecast data indicates atmospheric moisture levels will climb well above average for early June, providing an environment capable of producing efficient rainfall rates with any thunderstorms that develop.
Thursday Brings The First Round Of Storms
Rain chances will begin increasing late Wednesday night into Thursday, especially across western and northwestern Iowa.
Scattered showers and thunderstorms are expected to develop and gradually spread southeast across the state throughout the day. While not everyone will see rain continuously, periods of showers and thunderstorms are likely in many locations.
Some storms may become strong, with gusty winds and hail possible, particularly across portions of northern and western Iowa.
Friday Could Be Iowa’s Best Chance For Widespread Rain
Forecast confidence continues to increase that Friday will offer the greatest opportunity for widespread rainfall across Iowa.
A cold front moving through the state will interact with a warm, humid, and unstable air mass, resulting in additional rounds of showers and thunderstorms. Moisture levels will remain unusually high for this time of year, allowing storms to produce heavy downpours.
Current forecast models suggest many locations that receive repeated rounds of thunderstorms could pick up 1 to 2 inches of rainfall between Thursday and Friday, with localized higher amounts possible where storms repeatedly move over the same area. The exact placement of the heaviest rainfall remains uncertain and will likely shift over the coming days, but confidence is growing that at least portions of Iowa will receive a beneficial soaking rain.
Given recent dry conditions across much of Iowa, many areas can handle a significant amount of rainfall before flooding concerns develop. Even so, localized ponding of water, water-covered roads, and minor flooding issues cannot be ruled out in areas that receive multiple rounds of heavy rain.
Severe Weather Remains Possible
In addition to the heavy rain threat, some thunderstorms Thursday and Friday could become strong to severe.
The Storm Prediction Center has already outlined the northwestern half of Iowa in a Marginal Risk (Level 1 of 5) for severe weather on Thursday. Damaging winds and large hail would be the primary threats with any stronger storms that develop.
The severe weather threat on Friday remains more uncertain. While thunderstorms are expected to develop along an approaching cold front, forecast confidence is lower regarding how favorable the atmosphere will be for severe storms. Factors such as cloud cover, morning rainfall, and how much the atmosphere can recover during the day will play a significant role in determining the overall threat. As a result, any potential severe weather risk on Friday will be better defined over the next couple of days as forecast confidence increases.
For a more detailed breakdown of the severe weather potential and areas most at risk, be sure to check out our latest severe weather forecast article.
Looking Ahead
Rain chances may linger into parts of Saturday before a brief break develops later in the weekend. Long-range forecast guidance suggests another active weather pattern may return early next week.
For now, Iowa’s best opportunity for meaningful rainfall appears to arrive Thursday and Friday, with Friday currently looking like the day with the greatest potential for widespread showers, thunderstorms, and locally heavy rainfall. Forecast details will continue to be refined over the next few days, especially regarding where the heaviest rain axis ultimately develops.