Storm Record · Columbia, Dane, Jefferson, Sauk, Walworth Counties

August 18, 2005: Tornadoes across five counties

August 18, 2005

1.75″

Largest hail

75mph

Strongest gust

Tornadoes

NWS reports

What the National Weather Service recorded

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.

Source: NOAA Storm Events Database · episode 1198478

Every report, in the Weather Service's words

Where It Hit

Location	County	Hazard	Size	Report
Stoughton (2 NW)	Dane	Wind	75 mph wind	Rear-flank downdraft (RFD) damage occurred south of the F3 tornado that plowed through the area just north of Stoughton (Dane Co.). Numerous large trees were uprooted or had broken large branches. Several power-lines were damaged.
La Grange (1 W)	Walworth	Wind	64 mph wind	Several large trees were uprooted.
Oregon	Dane	Wind	60 mph wind	Several large trees were uprooted.
Ft Atkinson	Jefferson	Wind	60 mph wind	Several large trees were uprooted.
Cottage Grove (8 SSE)	Dane	Hail	1.75" hail
Loganville (3 SE)	Sauk	Hail	1.75" hail	Golf-ball sized hail caused extensive corn crop damage. This hail was associated with the supercell which spawned two tornadoes back in Vernon and Richland Counties, as well as the F2 tornado that passed through the old Badger Ammunition Plant in southeast Sauk County (south of the Baraboo Bluffs and Devils Lake State Park) and into Columbia County.
Ft Atkinson	Jefferson	Hail	1" hail
East Troy	Walworth	Hail	1" hail
Spring Green (2 SSW)	Sauk	Tornado	F1	This tornado spun up at 1630CST about 1.5 miles south-southwest of Spring Green, just inside the Sauk County line on the Wisconsin River. The tornado headed north-northeast for about 1.9 miles and dissipated at 1633CST about 0.5 mile east-northeast of Spring Green, on Rainbow Rd. just west STH 14. Minor roof damage in the village of Spring Green was noted on a couple buildings, and some large trees were uprooted, resulting in a rating of F1, and an estimated wind speed of 64-97 knots (73-112 mph). Average path width was about 50 yards.
Rockdale (2 SSW)	Dane	Tornado	F1	This tornado developed just north of the F3 Stoughton tornado path, at 1810CST about 1.6 miles south-southwest of Rockdale, or 0.2 mile southwest of the intersection of Hoopen Rd. and East Church Rd. The tornado tracked east along or near Hooopen Rd., until it dissipated at a location 1.3 south-southeast of Rockdale at 1815CST, or about 0.2 miles northeast of the intersection of Hoopen Rd. and Pleasant Rd. Many large trees were uprooted or twisted, and minor damage was inflicted on 3 homes and one pole shed. In addition, power-lines were knocked down. This tornado was rated F1 with estimated winds of 64-97 knots (73-112 mph). Average path width was about 50 yards.
Leland (4 NE)	Sauk	Tornado	F2	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.
Merrimac (2 W)	Sauk	Tornado	F0	A tornado spun up 1.8 miles west of Merrimac at 1700CST, along STH 78/113. The tornado headed southeast and dissipated 1.0 mile WSW of Merrimac at 1705 CST just short of the Sauk-Columbia County line in the Wisconsin River. Damage was confined to trees and power-lines. This tornado was rated an F0 with estimated wind speeds of 35-63 knots (40-72 mph). Average path width was about 50 yards.
Ft Atkinson (6 SSW)	Jefferson	Tornado	F1	This tornado spun up at 1844CST about 5.6 miles south-southwest of Fort Atkinson, where Grogan Rd. intersects with Vikerman Rd. It tracked east-southeast and damaged a couple farm sheds and damaged farm machinery on 3 farms. Tree damage and some minor crop damage was noted. It dissipated at 1853CST about 5.7 miles south of Fort Atkinson, or about 0.8 mile south-southeast of the intersection of CTH K and McMillen Rd. near a confluent spot on Allen Creek. This tornado was rated F1 with estimated wind speeds of 64-97 knots (74-112 mph). Average path width was 50 yards.
Lodi (5 NNE)	Columbia	Tornado	F0	A brief tornado spun up and dissipated at 1710CST about 4.5 miles north-northeast of Lodi, or about 1 mile south of the intersection of CTH CS and Smith Rd., just west of Smith Rd. Only minor vegetative damage was noted by a severe weather spotter in the area at the time. This tornado was rated as F0 with estimated wind speeds of 35-63 knots (40-72 mph).
Fitchburg (3 SE)	Dane	Tornado	F3	A strong and destructive tornado spun up at 1715CST about 2.8 miles southeast of the geographic center of Fitchburg (or 2.0 miles north of center of Oregon), about 400 yards southwest of the intersection of CTH MM and Schnieder Rd. It continued east-southeast to the southern edge of Lake Kegonsa and tore through residential neighborhoods about 1/3 to 1/2 mile north of CTH B (Civil Towns of Dunn and Pleasant Springs, and far-northern Stoughton). It moved over the crossing of CTH A with Interstate 90/39, and stayed close to CTH A to its exit point at 1905CST where CTH A crosses into Jefferson County, about 2.8 miles south-southwest of Rockdale. One person was crushed to death in their basement from fireplace and chimney bricks that crashed through the floor. Twenty-three (23) other people were directly injured. In addition, Emergency Management officials received reports of 2 other indirectly-related deaths associated with this strong tornado. In these two cases, the people were already very ill or suffering from a life-ending disease. Injuries they received during the tornado contributed (secondary) to their death, but were not the primary cause of death, based on medical examiner reports. Consequently, these additional two deaths do not appear in the official death tally in the header strip of this event. Numerous homes, businesses, farm buildings, vehicles, power-lines, trees, and other personal effects were either damaged or destroyed along its path that grew to a maximum width of about 600 yards north of Stoughton. As for residential structures, 220 sustained minor damage, 84 had major damage, and 69 were destroyed. As for business structures, 6 sustained minor damage, 1 had major damage, and 1 was destroyed. As for agricultural structures, 5 sustained minor damage, 5 had major damage, and 40 were destroyed. Total estimated damage amounts (directly-related) for private and public sectors combined was $35.06 M, broken down to $34.31 M in property damage and $750 K in crop losses, for the tornado segment in Dane County. This tornado was probably the 3rd most costly tornado in Wisconsin's recorded history (1996 Oakfield tornado and 1984 Barneveld tornadoes were more costly). The $34.31 M in property damage was broken down to private losses (total of 32.29 M) and public losses (total of $2.02 M), per Emergency Manager reports and NWS estimates. The private losses included a total of $25.45 M for residential structures, $1.29 M for businesses, $4.25 M for agricultural structures, $1.00 M for damage to vehicles, boats, and other personal effects, $200 K to agricultural machinery and tools, and $96 K in public road system damage. The public losses making up part of the $34.31 M consisted of $2.02 M in damage to public utility systems. The $750 K in damage attributed to crop losses occurred on an estimated 1,550 acres of land. Additional monetary costs incurred in the public sector (totaling $1.84 M) which are considered indirectly-related damage expenses, and not included in the "direct" totals listed in the header-strip of this event, include: $1.38 M in debris clearance, $308 K in protective measures, and miscellaneous damage/expenses of $144 K. Therefore, the grand total of direct and indirect damage amounts and expenses attributed to this tornado segment in Dane county totaled about $36.89 M.Just south of the tornado, extending out another mile or so, tree and power-line damage resulted from rear-flank downdraft damage - in some cases south to STH 51. This damage is separate from tornado damage, and isn't included in the numbers in previous sentences. Debris from this tornado was lofted by the parent's updraft and carried downstream to scattered locations in the counties of Jefferson, Waukesha, Milwaukee, Walworth, Racine, and Kenosha. This tornado was extensively photographed and video-taped by storm spotters (amateur radio operators, etc.), storm chasers, and private citizens. On occasions, this tornado displayed multiple-vortex characteristics. Due to partial back-building (to the west-southwest) of the supercell's updraft tower, this tornado moved slowly, and was described by some eyewitnesses and spotters as being nearly stationary at times north of Stoughton. The overall slow movement (supercell moved at 12-17 knots, or 10-15 mph), coupled with structures that were not thoroughly reinforced (based on NWS damage survey), allowed the tornado's cyclonic winds to more severely damage buildings in its path. Consequently, although some of the worst damage resembled what would be left by a F4 tornado for well-built homes, this tornado was rated at the top of the F3 category with estimated winds near 174 knots (200 mph). The F3 category has estimated wind speeds of 137-179 knots (158-206 mph). A sampling of newspaper headlines and personal quotes included: "The Sky Just Exploded," "Hard to Believe There Weren't More Deaths," "New Technology Lowers Tornado Deaths," "Counting Losses, Blessings," "It Was Probably The Most Intense Storm In The Country This Year," "It's a Mess Out Here," and "I've Never Experienced Anything Like This." The tornado cut electrical power for 1700 customers in the Stoughton area. The estimated average path length was about 175 yards.
Okee (5 W)	Columbia	Tornado	F2	This tornado was a continuation of the "Leland" F2 Sauk County tornado that passed through the Badger Ammunition Plant grounds. It crossed into Columbia County from Sauk County at 1655CST about 5.4 miles west of Okee, or 1.2 miles northwest of the intersection of Gastrow Road and STH 188. This tornado headed east-southeast for 3.4 miles, while weakening, and ended at 1703CST about 3.2 miles southeast of Okee, or 0.2 mile southeast of the intersection of CTH J and Occonor Road. Some tree, power-line, and crop damage was noted, resulting in a F1 damage rating in Columbia County. Average path width was about 125 yards.
Spring Green (4 WSW)	Sauk	Tornado	F1	This tornado in Sauk County was a continuation of the "Clyde" tornado from Iowa County. It crossed into Sauk County at 1626CST at a point 4 miles west-southwest of Spring Green, or 1.0 miles southwest of the intersection of Kennedy and Dyke Roads. The tornado continued northeast 3.3 miles and dissipated at 1633CST about 2.3 miles NW of Spring Green, or 0.7 mile north-northwest of the intersection of Pearl Rd. and STH 14/60, just short of CTH G. Only tree, power-line, and some crop damage was noted, resulting in a F1 rating, with estimated wind speeds of 64-97 knots (73-112 mph). This tornado was well photographed. Average path width was about 50 yards.
Dane (2 WSW)	Dane	Tornado	F0	At 1717CST, a tornado developed 2.0 miles west-southwest of the village of Dane (Dane Co.) It traveled northeast and ended 0.8 miles north of Dane at 1721CST. Corn crop damage was noted and this tornado was rated an F0. The damage was noticeable from any of the local roads, but was seen only from an airplane flyover conducted by a severe weather spotter.
Busseyville (3 NNW)	Jefferson	Tornado	F1	This tornado was a continuation of the F3 tornado that tore through the area north of Stoughton (Dane Co.). It crossed into Jefferson County at 1805CST where CTH C starts, about 2.8 miles north-northwest of Busseyville (Jefferson Co.). It traveled east-southeast for about 1.6 miles and dissipated just south of the end of Hartwig Road, about 2.2 miles north-northwest of Busseyville, at 1805 CST. Damage to large tees was noted, as well as some minor crop damage. This portion of the tornado track was rated F1 with estimated wind speeds of 64-97 knots (73-112 mph). The average path width was 50 yards.
Ft Atkinson (1 SW)	Jefferson	Tornado	F1	The fourth of five tornadoes in or near Fort Atkinson developed at 1837CST about 1.1 mile southwest of Fort Atkinson in a grassy area west of The Fireside Dinner Theater which is on STH 26 Business. This tornado moved due east through the southern part of the city of Fort Atkinson, just missing The Fireside which had some 500 guests inside, and dissipated 1.3 southeast of the city center on STH 12/89 about 0.2 mile south of Fox Hill Rd. Twenty residential homes and 5 businesses sustained minor damage, one business was destroyed, numerous many large trees were uprooted or twisted, some power-lines were damaged, and minor crop damage was noted. As for business losses, a portion of the roof of the Rock River Lanes was peeled back, the Best Western Motel had minor sign and roofing damage, and the Fort Plaza Mini Warehouse was destroyed. This tornado was rated as F1 with estimated wind speeds of 64-97 knots (74-112 mph). The average path width was about 30 yards.
Ft Atkinson (3 SE)	Jefferson	Tornado	F0	The fifth of five tornadoes in or near Fort Atkinson developed at 1845CST about 3.2 miles southeast of Fort Atkinson near the intersection of CTH M and CTH N (0.3 mile northeast of this intersection). It moved east across CTH N and then quickly dissipated at 1846CST. Several large trees were uprooted, one corn bin was ripped apart, and two other corn bins were damaged. Minor crop damage was noted. This tornado was rated as F0 with estimated wind speeds of 35-63 knots (40-72 mph). Average path width was 30 yards.
Ft Atkinson (6 W)	Jefferson	Tornado	F0	The first of five tornadoes in or around Fort Atkinson developed at 1815CST, 5.5 miles west of Fort Atkinson, or near the end of West Grove Rd. It headed southeast and dissipated 5.2 miles west of Fort Atkinson at 1817CST, or about 0.2 mile north-northeast of the intersection of STH 106 and Kreutz Rd. Two mobile homes minor damage, one residential home was damaged and its 3-car garage was destroyed, one farm shed was destroyed, many large trees were uprooted, and minor crop damage was noted. This tornado was rated F0 with estimated wind speeds of 35-63 knots (40-72 mph). Average path width was 20 yards.
Ft Atkinson (5 W)	Jefferson	Tornado	F1	The second of five tornadoes in or near Fort Atkinson developed at 1820CST just east of the first tornado, about 5 miles west of Fort Atkinson, or about 0.3 mile north of the end of East Grove Rd. It tracked cyclonically to the southwest, south, and then southeast where it dissipated about 0.4 mile northeast of the intersection of STH 106 and Kreutz Rd at 1823CST (about 5 miles west of Fort Atkinson). A trailer with a truck inside was tipped over, resulting to damage to both. One residential home sustained minor damage, many large large trees were uprooted or twisted, and minor crop damage was noted. This tornado was rated as F1 with estimated wind speeds of 64-97 knots (74-112 mph). Average path width was 25 yards.
Ft Atkinson (4 W)	Jefferson	Tornado	F1	The third of five tornadoes in or near Fort Atkinson developed at 1827CST, about 4.1 miles west of Fort Atkinson, or 1.0 mile west-northwest of the intersection of STH 106 and CTH J. It tracked southeast across Burnham Rd. After crossing North Shore Drive, it dissipated in a swamp about 0.4 mile southwest of the intersection of STH 106 and the STH 26 bypass at 1832CST, or about 2.7 miles west-southwest of Fort Atkinson. One residential home sustained minor damage, two shead used for horses sustained roof and siding damage, many large trees were uprooted or twisted, and minor crop damage was noted. This tornado was rated as F1 with estimated wind speeds of 64-97 knots (74-112 mph). The average path width was 30 yards.

Source: NOAA Storm Events Database, Wisconsin

Service areas this storm touched