Northwest Iowa — Another thunderstorm system rumbled through northwest Iowa Monday evening, July 10th, with some severe storms leaving damage in their wake.
In our part of northwest Iowa, according to information received from the National Weather Service, a Severe Thunderstorm Watch was issued for the area at 3:10 p.m. It included over half of the counties in Nebraska, six counties in southeast South Dakota and 15 counties in greater northwest Iowa.
They tell us that in our area of Lyon, O’Brien, Osceola, and Sioux counties, a severe thunderstorm warning was issued for western Sioux County Iowa, and both southeastern Lincoln County and northeastern Union County in South Dakota at 4:17 p.m. for a storm nine miles northwest of Hawarden, moving east.
They say damage reports started coming in for our area at 4:42 p.m. with multiple 3-4-inch tree limbs downed in Rock Valley. A severe thunderstorm warning was then issued for northeastern Sioux County at 4:47 p.m.
The next report the National Weather Service received was just a minute later, when 1.5-inch hail was reported, along with 50-mile-per-hour wind gusts a mile west of Hull. (1.5-inch hail is the size of ping pong balls or walnuts.)
At 5:03 p.m., they issued a severe thunderstorm warning for southeastern Lyon and northeastern Sioux counties for a storm over Matlock. A little later, at 5:11 p.m., 1-inch hail was reported at Matlock. (That’s about the diameter of a quarter.)
At 5:12 p.m., the weather service issued a severe thunderstorm warning for southeastern Lyon, all of Osceola, northeastern Sioux and northern O’Brien counties, for a storm, again over Matlock.
The first report from O’Brien County came a few minutes later at 5:15, with a thunderstorm wind gust estimated at 60 miles-per-hour, four miles north-northeast of Sheldon, near Ritter. They also reported 1.75-inch or golf ball-sized hail at that location.
At 5:19 p.m., hail estimated at 1.25 inches fell in Ashton. That’s about the diameter of a half dollar coin. Just two minutes later, 1-inch hail was reported at Sanborn. At about that same time, golf ball-sized hail was reported again, this time in Ashton. The report noted that hail ranging in size from pea to golf ball size had fallen. They also said tree limbs two to three inches in diameter were also downed in Ashton.
A little later, at about 5:30 p.m., the roof of an outbuilding six miles east of Melvin was tossed 200 yards and a large walnut tree was broken off. After that point, the damage reports moved out of our area and into Dickinson County, where similar reports were received.
At 5:43 p.m., weather service officials issued a final severe thunderstorm warning that included parts of our area. In the watch were eastern Osceola, all of Dickinson, northern Clay, and northeastern O’Brien counties in Iowa and southeastern Jackson County, Minnesota. That was for a storm seven miles south of Harris that was reported to have 60-mile-per-hour wind gusts and half-dollar-sized hail.
The storms were spotty as they rolled through the area. The most intense precipitation occurred in mostly rural areas between Sheldon and Ashton, centered mostly near Ritter around 5:20 p.m. When it was all done, reports that Rock Rapids had two-hundredths of an inch, George had a few sprinkles, just a trace of precipitation. Downtown Sheldon, however had substantially more, at 65-hundredths, all falling within the course of about 45 minutes. The most rainfall that has been reported to KIWA was 1.39 inches of rain that fell near Matlock, accompanied by 1 inch hail.
