Published September 27, 2017
After a powerful complex of storms brought hail, damaging winds and heavy downpours to the Upper Midwest Sunday night, new rounds of severe thunderstorms will rattle the midwestern United States early this week.
“The active weather pattern that kicked off Sunday night will continue in the Midwest this week,” AccuWeather Senior Meteorologist Michael Doll said.
Sunday night’s complex of storms will continue to push southward through Monday morning, threatening eastern Iowa and the northern half of Illinois. Shortly after these storms weaken, a new round will erupt later Monday.
The boundary left behind by Sunday night’s storms will serve as the focal point for the new round of storms that fires up Monday afternoon and evening.
“Severe thunderstorms are forecast to develop through north-central Illinois through northern Indiana on Monday afternoon,” according to AccuWeather Meteorologist Kyle Brown.
“All hazards will be on the table from these thunderstorms, with the threat for hail perhaps the greatest in the afternoon and evening as storms begin their life cycle,” Brown said. “Then, overnight, storms can transition to pose more of a heavy rain and wind threat with isolated areas receiving 2 inches of rainfall or more along with wind gusts near 50 mph.”
Motorists can be significantly impacted by the storms, as blinding downpours can quickly reduce roadway visibility and increase the risk of vehicles hydroplaning when traveling at highway speeds.
Storms into Monday night will threaten portions of Interstate 80 from just west of Cleveland, to just south and east of Omaha, Nebraska. The cities of Fort Wayne and South Bend, Indiana, as well as Chicago, Peoria and Springfield, Illinois, may all be impacted by severe thunderstorms.
Because the storms are feeding off an unusually moist and humid environment and will be moving rather slowly, the risk of flash flooding can emerge as the most significant and life-threatening impact from the storms.
“The risk of flash flooding can be particularly dangerous overnight when it is hard to see water covering roadways,” Brown added.
In the past week, some areas of northern and central Indiana have received 3 to as much as 6 inches of rain. It is quite possible that many locations in this corridor double those amounts in the next three days, making this additional rainfall especially problematic.
Residents living near streams, creeks and rivers should closely monitor water levels and have an evacuation plan in place should floodwaters encroach on their home and property.
Brown noted that more dangerous thunderstorms can impact a corridor from near Kansas City, Missouri, to Toledo, Ohio, Tuesday. Thus, residents living in these areas will need to remain on alert for two consecutive days and seek shelter at the first clap of thunder or first sighting of lightning.
Strong, gusty winds and flooding downpours will again be the two primary threats from storms in this corridor Tuesday.
However, another area of unsettled weather is forecast to emerge from the northern Rockies into the northern Plains late in the day Tuesday, triggering a new complex of severe thunderstorms.
Storms should first ignite in the eastern Dakotas late Tuesday afternoon before forming into an organized complex.
At first, large hail and even a few tornadoes may be the primary threats from these storms before damaging winds and flooding downpours become the dominant concerns by Tuesday night as the complex races south and eastward through Minnesota.
It may be until the middle of the night until storms reach Minneapolis and surrounding communities, putting a large number of people at risk while they sleep if and when severe weather threatens.
How much intensity the storms lose as they dive southeastward early Wednesday morning will determine if downpours and destructive winds reach Chicagoland or whether generally weaker storms impact the city.
By later in the week, the best chance of severe thunderstorms should shift farther south into the central U.S., but may return to the Midwest to kick off the upcoming weekend.