F2 tornado in Sauk County, Wisconsin

This tornado spun up from the same supercell thunderstorm that spawned the "Viola" tornado earlier in Vernon and Richland counties. This Sauk County tornado spun up at 1633CST about 3.6 miles northeast of Leland, or about 1/4 mile south of the intersection of Ruff and Pine Hollow Roads. The tornado headed east-southeast for about 11.1 miles in Sauk County, and crossed the Columbia County line at 1655CST about 4.5 miles north-northeast of Prairie du Sac, between Wiegans Bay and a boat launch site. This tornado crossed CTH C about 0.5 mile west of Stones Pocket Road, and moved through old Badger Ammunition Plant just south of the greatest density of roads within the Plant grounds. This rain-wrapped tornado was video taped and photographed, and damaged many structures, trees, and power-lines. As for residential buildings, 10 received minor damage, 1 had major damage, and one was destroyed. One business building had minor damage. As for agricultural buildings, 5 received minor damage, and 6 were destroyed. This tornado was rated an F2 with estimated winds of 98-136 knots (113-157 mph). Average path width was about 150 yards.

The largest single-day tornado outbreak in Wisconsin recorded history for south-central and southeast Wisconsin occurred on August 18, 2005. Sixteen tornadoes were documented on this day in south-central and southeast Wisconsin, a new single-day record. A line of supercells developed and pushed across south-central Wisconsin during the afternoon hours, and then pushed east across southeast Wisconsin during the evening hours. Most of the tornadoes were associated with two supercells. One main supercell tracked across Sauk County and then into Columbia, producing one F0 and one F2 tornado. The F2 tornado crossed into Columbia County. Another main supercell produced an F3 tornado that devastated the area north of city of Stoughton (Dane Co.), and a weaker F1 tornado just south of the city of Rockdale (Dane Co.). This supercell then tracked into southwestern Jefferson County a short time later, producing two F0 tornadoes and four F1 tornadoes. The sixteen (16) tornadoes contributed largely to both the new state record of 27 tornadoes on a single day, and 62 tornadoes for a calendar year. In additiion, there were scattered reports of funnel clouds, damaging straight-line, downburst winds, and large hail across south-central and southeast Wisconsin. The total direct damage estimate for the afternoon and evening tornado and severe weather outbreak in south-central and southeast Wisconsin on August 18th was about $36.6 M ($35.7 property and $948 K crop). Additional indirect costs totaled almost $1.9 M, resulting in a total direct and direct cost of about $38.5 M. Synoptically, a surface low pressure system was located over extreme southeast Minnesota early in the afternoon. A warm front extended east southeast from the low with dew points pooling in the lower 70s along it. The surface low moved east into east central Wisconsin by 2100CST that evening. Favorable wind shear associated with the warm front, combined with the strong instability supplied by the heat and humidity, helped to produce numerous tornadic supercells.