Intense thunderstorms brought strong winds and heavy rains to central and southern Minnesota on Monday July 28 into very early July 29, 2025. The storms produced wind damage to trees and power lines, as well as additional flooding in parts of western Minnesota already hit hard by excessive rainfall.
Much of the region was still reeling from severe weather and flooding one day earlier, on Sunday July 27th, as power remained out to around 10,000 customers around the state, and parts of Stevens and Big Stone counties were still flooded or flood-damaged.
Plenty of humidity remained across southern Minnesota, and a disturbance with strong winds aloft was moving out of South Dakota, towards the moisture and energy-rich air mass. Forecasters had become concerned that a major, destructive outbreak of severe weather could affect central and southern Minnesota.
Fortunately, what happened instead was damaging and disruptive to be sure, but was not of the intensity or scale of the recent "Bemidji Blowdown" of June 20-21, which had appeared possible.
Strong thunderstorms developed in northeastern South Dakota during the afternoon, and gradually expanded and intensified as they moved into western Minnesota. One of their first acts was to hammer the exact same areas near Morris that had been flooded one day earlier. These areas received some of the heaviest rainfall from the entire event, because the storms were still moving quite slowly in their vicinity. It only took 1-2 inches of rain to generate new floods and to worsen existing ones. The flood came without large hail.
The storms continued growing, strengthening, and picking up speed as they headed eastward and southeastward for the remainder of the evening. Wind gusts of 50-60 mph were common as the storms passed into the Twin Cities area, with isolated higher gusts, included one measured to 65 mph in Shakopee. The winds blew many limbs and trees onto power lines, with a rapid increase power disruptions and failures.
The thunderstorm winds increased further in southern and southeastern Minnesota, with gusts measured to 70 mph at the Owatonna airport, and to 76 mph at the Rochester airport (near Stewartville). Approximate 150,000 customers lost power during the the storm.
As intense as these storms were, the swath of damage does not qualify this event as a derecho (pronounced "deh-REY-cho"). The swath length appears to have reached just over 250 miles, which is the minimum length required in the NOAA Storm Prediction Center's definition of a derecho, but there were not enough reports or estimates of winds exceeding hurricane force (74 mph) along that track. Much stronger winds occurred from an extreme thunderstorm that tracked from southern South Dakota into northern and eastern Iowa, with numerous gusts above 75, 80, and even 90 mph recorded. That storm may have a long enough track length to qualify as a derecho.
July 30, 2025
KAB