(WDAY-WDAZ) The National Weather Service has issued its storm damage survey of last Tuesday’s storms. The most impressive storm produced four separate tornadoes along with a tremendous amount of additional straight-line wind damage as well as hail. A great deal of the straight-line wind damage occurred in a wide area to the southwest of the ongoing mesocyclone.
The first tornado from this supercell touched down northwest of Northwood and remained on the ground 4.5 miles with peak winds estimated at 90 mph.
A new tornado formed eight miles east of Hatton and travelled southeast for 23 miles. This was a multi-vortex tornado and was often obscured visually because it was surrounded by wind and hail. At its largest, the tornado was 1200 yards wide and produced winds of 135 mph. It weakened and curved northeast north of Hillsboro. Extreme straight-line winds of 80-100 mph formed to the southwest of this tornado in an area of the supercell known as the Rear Flank Downdraft. It was this wind that did all of the damage to the town of Hillsboro.
As the second tornado curved to the northeast and shrunk, a third tornado formed east of Hillsboro, swelled to 600 yards wide, and tracked six miles across the Red River to within a mile of Halstad with winds to 125 mph. This tornado snapped steel power poles and destroyed multiple grain elevators before roping out.
The final tornado formed north of Borup, grew to 500 yards wide, and traveled 13 miles to near Ulen. The storm continued southeast producing widespread straight line wind damage throughout Becker and Otter Tail Counties.
The attached video shows the satellite-radar imagery followed by the Doppler radar loop and ends with the Doppler velocity loop which clearly shows the powerful rotation around this dangerous storm.
StormTRACKER Meteorologist John Wheeler