A complex of intense thunderstorms with scattered damaging winds and very heavy rains moved across western, central, eastern, and southern Minnesota from the evening of Tuesday July 25th into the morning hours of Wednesday July 26, 2023.
Strong thunderstorms first formed during the evening near the Minnesota border with both Dakotas, along the edge of a moist and extremely unstable air mass. These thunderstorm cells congealed into large complex of storms, which then intensified rapidly and tracked east-southeastward from near Wheaton, to the Willmar area, to the central and southern Twin Cities , eventually crossing the St. Croix and Mississippi rivers into Wisconsin.
This may have been the longest-lasting and best-organized organized thunderstorm complex of the generally inactive 2023 thunderstorm season (so far). For much of its journey across Minnesota, the storms maintained a classic, bulging, comma shape on radar. This shape is often referred to as a "bow echo," because the leading edge takes on the shape of an archer's bow, and can be an indicator of strong, gusty, and even damaging winds.
True to form, the bow echo did produce very strong winds at times, especially in Traverse, Stevens, Pope, Swift, and Kandiyohi counties. A MnDOT sensor near Murdock reported winds gusting 72 to mph; trees and power poles were snapped near New London; and tree damage and power outages were reported across much of that part of west-central Minnesota.
The large thunderstorm cells associated with the main complex, and other smaller but slower-moving storms that formed elsewhere throughout the night, produced to some much-needed heavy rainfall totals across parts of Minnesota. A swath of 1 to 3 inches fell from the Alexandria and Morris areas, southeastward to the Wisconsin border, including Willmar, Hutchinson, New Prague, Zumbrota, and the central and southern Twin Cities area. Several observers reported over three inches of rainfall, with 4.40 inches reported by a CoCoRaHS observer near Glenwood. Another area of heavy rainfall occurred with slow-moving thunderstorms in northwestern Minnesota. One to 2.5 inches of rain fell from Karlstad, to Warren, to Thief River Falls.
Despite the size, duration, and intensity of these storms, they missed more areas than they hit. Only about 15% of the state received an inch of rain or more, and over half the state-- mostly in the north, northeast, and southwest-- received a quarter-inch or less. Thus, for most of the state this event did little or nothing to slow down the developing drought conditions.
July 26, 2023