Summer Thunderstorms Threaten Millions in Upper Midwest and Northern Plains

More than 3 million people are under the threat of dangerous storms across the Upper Midwest and the northern Plains this week. Read on for a detailed look at the timing, locations, and expected impacts associated with this volatile weather maker.

Severe Weather Impacts to Persist Through Thursday for Northern U.S.

Days of severe storms are forecast to train over the same areas of the northern Plains and into the Upper Midwest for much of the week. The classic summer storm line will bring the chance of damaging winds, heavy rain, and flash flooding through at least Thursday.

The next round of storms will follow the lead of Monday's severe weather event. The Storm Prediction Center (SPC) out of the National Oceanic and Atmospheric Administration (NOAA) said that it fielded at least six preliminary tornado reports on this day alone.

The thunderstorms and resulting tornadoes wreaked havoc across northern Minnesota. Emergency shelters for displaced residents are now open in the community of Detroit Lakes. The National Weather Service (NWS) said that it expects tornado survey crews to be on the ground in Detroit Lakes by Tuesday afternoon.

Farther to the east, residents of Walworth County, Wisconsin, are still cleaning up the mess left by a wave of storms that hit the region on Friday, July 3. Forecasters are warning that this zone of the Upper Midwest will be under an increased risk of flash flooding later this week because so much of the ground is still saturated

Most of the thunderstorm activity in the coming days will ignite in the afternoon hours due to the natural heating of the day. These storms are most likely to form around the ridge of high pressure tethered over the central U.S.

The atmospheric setup will support the development of the "training" effect throughout the Upper Midwest, acting like boxcars on a train track. Like a train, the individual thunderstorm cells will roam over the same swath of land in a line.

Timing and Location of This Week's Storm Activity

NOAA's Weather Prediction Center (WPC) recently issued a Level 2 out of 4 flash flood threat for the eastern flanks of the Dakotas and central portions of Minnesota and Wisconsin. This threat is in place through Wednesday morning. In addition to the heavy rain on tap, the storms will also pack winds up to 75 mph.

Minneapolis is the largest city located under this umbrella of concern. The Twin Cities are forecast to see just a slight chance of rain or an errant storm on Tuesday afternoon. The odds of storms will increase in the evening hours and into the start of the day on Wednesday. It could be a messy morning commute on Wednesday for residents of Minneapolis, St. Paul, and beyond. Gusty winds and small hail are possible with Wednesday's storms.

Highs will approach the 90-degree mark on Tuesday before topping out in the upper 70s on Wednesday in Minneapolis. A drier and warmer weather pattern will round out the week in this region. Minneapolis is expecting sunny skies and highs that climb back up into the mid to upper 80s on Thursday and Friday.

The threat of severe weather will move to the south on Wednesday, encompassing a zone from the central Plains to the east into south-central Wisconsin. Communities in the line of fire of Wednesday and Thursday's action include North Platte, Nebraska, and Rochester, Minnesota.

For instance, North Platte is bracing for the greatest concentration of storms to roam this part of the northern Plains on Thursday. The forecast is calling for partly cloudy skies early with storms erupting in the afternoon and evening hours. Temperatures will inch up into the upper 80s before sliding to about the 60-degree mark overnight.

Moving into Wisconsin, the city of Green Bay will wake up to mostly cloudy skies on Wednesday. Storms will come to life in the afternoon and evening hours as the mercury climbs into the mid 80s. Sustained winds will clock in at 10 to 15 mph from the west-southwest. The stormy hazards will linger into the overnight hours in Green Bay, making it important to enable all smartphone notifications before heading to bed.  

By the time that the storms wrap up late Thursday, a large area of the Upper Midwest should expect 1 to 2 inches of rainfall. These rainfall totals are in store for cities such as Minneapolis, Duluth, and Marquette. Within this zone, localized pockets of 3 to 5 inches are possible.

A secondary zone of severe weather and the accompanying threat of flooding is also unfolding across New England, the Mid-Atlantic, and some parts of the Appalachians. A slow-moving storm system continues to drop copious amounts of moisture across portions of New Jersey, Pennsylvania, Connecticut, Rhode Island, and the New York City area.

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