By Kyle Elliott, AccuWeather meteorologist
July 14,2017, 2:33:12PM,EDT
Following sunshine and a much-needed break from flooding rainfall, severe thunderstorms will return to the Upper Midwest on Saturday.A storm system moving southward from Canada is forecast to trigger isolated but powerful thunderstorms across much of Wisconsin, southern and eastern Minnesota and northern Iowa beginning on Saturday afternoon and continuing through the overnight hours.
“Thunderstorms will develop by Saturday afternoon across the Upper Midwest, and some of these thunderstorms will have the potential to become severe and feed off the warm, humid air that will briefly make a comeback,” AccuWeather Meteorologist Ryan Adamson said.
Many locations in the Upper Midwest have received 2 to as much as 6 inches of rain in the past week, with the heaviest, repeated rainfall inundating areas stretching from northern Iowa to southwestern Wisconsin and northern Illinois.
It would take as little as 1.5 to 2 inches of additional rainfall in a short amount of time in these areas to result in flash flooding of streams, creeks and rivers. Lives and property may be at risk as the potential exists for washed-out area roadways.
Major flooding was in progress on both the Fox and Des Plaines rivers in northern Illinois and southeastern Wisconsin during Friday morning. A crest may not occur in some locations until late in the weekend or early next week.
The main threats from the storms into Saturday night will be damaging winds and hail. However, even with the isolated nature of the storms, highly localized flooding is possible.
Any additional heavy rainfall will only exacerbate ongoing flooding issues, threaten to delay recovery efforts in areas where waters have begun to recede and put even more homes and property at risk for significant water damage.
“Minneapolis and Rochester, Minnesota, and La Crosse and Green Bay, Wisconsin, are just a few of the cities at risk for severe weather,” Adamson added.
Motorists traveling across Interstates 90 and 94 throughout Wisconsin and Minnesota should be prepared for travel delays and reduce speeds in heavy downpours, as it only takes a small amount of water on roadways to increase the risk for vehicles to hydroplane.
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Sporadic power outages are possible where the strongest winds occur, and trees can easily be uprooted or blown down when battered by gusty winds for as short as a few minutes.
Adamson stated that as the storms push southward and eastward into the first half of Saturday night, they should begin to weaken before reaching locations such as Grand Rapids, Wisconsin, and Chicago.
Residents living within the threat zone should seek shelter if thunder is heard or lightning is seen and keep a weather radio handy to monitor the latest severe weather alerts.
Dry weather should return to the Upper Midwest on Sunday. However, another round of damaging thunderstorms and potentially heavy rainfall may threaten these same areas again by the first half of next week.