Flash Flooding and Flood in Wisconsin, August 22, 2000

A mesoscale convective system (MCS) moved east across southern Wisconsin and generated scattered severe downburst winds, flood-producing rains, and intense lightning strikes. The powerful winds leveled some trees in the Brandon area, with one tree falling on and damaging a vehicle. A separate wet microburst struck the city of Ripon (Fond du Lac Co.) with winds estimated to 56 knots (65 mph), resulting in some downed trees or tree limbs. In addition, unofficial heavy rains of 3.5 to 4.5 inches fell in about 1 to 1.5 hours in Ripon, resulting in flash flooding. Water depths quickly reached 1 to 3 feet in and around Ripon. Manhole covers popped and damaged a vehicle in the city, and a railroad bed was washed out by the flood waters. Several cars stalled in the deep water. The severe storms moved east through the Fond du Lac city area, where their winds pushed over more trees. Urban flooding affect much of the city due to the heavy rains. Some cars were pushed down a flooded road in the central part of the city where water depths were 1 to 2 feet. Several intense lightning strikes knocked power transformers out of service in and around the city of Fond du Lac. This resulted in the loss of electrical power to 3,833 customers. A funnel cloud was spotted east of Eden. The thunderstorms then moved east into Sheboygan County where flash flooding affected the Plymouth to Sheboygan Falls area. Water depths on roads in this area reached 1 to 3 feet, and gravel shoulder washouts were noted. Downburst winds pushed over some trees north of Elkhart Lake. Urban flooding was reported in the city of Sheboygan.Synoptically, a low pressure was found over western Kansas with a warm front east through southern Iowa to central Illinois. A secondary surface trough extended northeast through Fond du Lac and Sheboygan counties. Aloft, a vorticity maxima moved across southern Minnesota through southern Wisconsin. Radar imagery clearly showed the embedded MCS to have Neddy-Eddy characteristics (counter-clockwise rotation). The comma-head portion of the MCS moved over Fond du Lac and Sheboygan counties, resulting in many echoes training over the same spot. South of the warm front one could find surface dewpoints in the 70 to 75 range.