 Chase photograph of the Oakfield tornado. (Courtesy Cailyn Lloyd) | |
| Meteorological history | |
|---|---|
| Duration | 3 hours, 8 minutes[1] |
| Tornado outbreak | |
| Tornadoes | 12[2] |
| Maximum rating | F5 tornado |
| Highest winds | 265 mph (425 km/h) |
| Overall effects | |
| Fatalities | 0 fatalities, 17 injuries[3] |
| Damage | ≥$40 million(1996 USD)[4] |
| Areas affected | Wisconsin |
Part of thetornado outbreaks of 1996 | |
The1996 Oakfield tornado outbreak was a severe weather event that occurred on July 18, 1996, inWisconsin,United States, primarily affecting the village ofOakfield.[3] The outbreak produced 12tornadoes,[2] with the most significant being anF5 tornado which caused severe damage to the village and the surrounding areas. No deaths were associated with the outbreak, with 17 injuries in total.[3]
The most intense tornado of the outbreak initially touched down at 6:05 p.m.CST (00:05 UTC) 4 miles northwest of Oakfield, before rapidly intensifying to F5 strength just east of the village. Estimated wind speeds reached 265 mph (426 km/h)[5] in the tornado's core as it carved a path approximately 20 miles (32 km) long.[3] Destruction in Oakfield included leveling homes, sending vehicles airborne, bending steel rebar, and sweeping crop fields clean.[6] The Oakfield tornado remains one of the costliest tornadoes in the state's history, with the estimated damage costs at US$40 million.[4]
On July 18, 1996, the meteorological conditions leading to the Oakfield tornado outbreak were influenced by the presence of a nearby shifting weather boundary, known as abaroclinic zone. This boundary generated strongcyclonic rotation around asurface low-pressure center overMinnesota.[7][2] Warm and moisture-laden air from theGulf of Mexico flowed northward into theUpper Midwest due to a dominant southerly wind pattern. Strong fronts displayedfrontogenetic behavior, with frontogenesis at 850 hPa level curving from the border ofSouth Dakota andNebraska to Wisconsin, leading to strong ascent in the warm sector of the surface low-pressure system.
Despite these conditions, no severe storms occurred in the morning hours. This was because of a highconvective inhibition (CIN) value caused by the presence of anelevated mixed layer (EML) and a 550 hPa inversion, which made it difficult for convection to break through. Additionally, the effects of daytime heating had not yet weakened the inversion. As the day progressed, daytime heating and evolving atmospheric conditions allowed the cap to be broken and provided the necessary ingredients for the development of the severe weather outbreak, including the devastating F5 Oakfield tornado.[2]
By 3:33 PM CST, theNational Weather Service inMilwaukee/Sullivan saw the potential for severe weather, including tornadoes, and issued the firsttornado watch which covered a majority of Wisconsin, followed by a second at 6:47 PM.[5]
| FU | F0 | F1 | F2 | F3 | F4 | F5 | Total |
|---|---|---|---|---|---|---|---|
| 0 | 6 | 4 | 1 | 0 | 0 | 1 | 12 |
| F# | Location | County / Parish | State | Start Coord. | Start Time (UTC) | Path length | Max width | Summary |
|---|---|---|---|---|---|---|---|---|
| F1 | SW ofTomahawk to W ofGilbert | Lincoln | WI | 22:20 | 3 miles (4.8 km) | 100 yards (91 m) | Three cottages, one home and a tavern were damaged. A garage was removed from its foundation and two boats were flipped.[8] | |
| F1 | NE ofPrinceton | Green Lake | WI | 23:15 | 2 miles (3.2 km) | 125 yards (114 m) | Damage was limited to trees.[9] | |
| F2 | S ofJericho toMarytown | Calumet,Fond du Lac | WI | 00:05 | 6.4 miles (10.3 km) | 200 yards (180 m) | North of Marytown a couple dozen barns, sheds and homes were damaged or destroyed. In Marytown a house trailer, three homes and a machine shed were destroyed. In rural Calumet County two barns, trees, crops were damaged and calf houses were thrown 1,000 feet (300 m). One person was injured.[10] | |
| F5 | Oakfield to N ofMarblehead | Fond du Lac | WI | 00:05 | 13.3 miles (21.4 km) | 400 yards (370 m) | Four homes were swept from their foundations, and automobiles were carried 400 feet (120 m) through the air and mangled beyond recognition. Some of the homes were anchor-bolted to their foundations, and rebar supports along the perimeter of one home were bent over at a 90-degree angle. The Friday Canning Company was also leveled, sweeping up millions of empty cans and leaving them scattered over a 50 miles (80 km) radius. Out of the 327 homes in Oakfield, 47 were destroyed, and an additional 56 homes, as well as numerous businesses and churches, suffered heavy damage. 500 acres (2.0 km2) of crops were also wiped away with only 1-inch stubble left. Damage totals reached $39.5 million (1996 USD) and 12 people were injured. The originalNational Weather Service report from Milwaukee/Sullivan categorized the tornado to be an F3 to F4 tornado on theFujita scale. It was later upgraded to an F5, the most intense category tornado possible and the only F5 tornado to hit theUnited States that year. Collectively, a total of 60 homes, six businesses, a canning company, two churches, 18 barns, and several sheds were destroyed while 150 homes and businesses were also damaged.[11] The tornado was also documented by at least three experiencedstorm chasers.[12] A weaker tornado also hit the area 20 minutes later.[6] | |
| F0 | Marytown | Fond du Lac | WI | 00:07 | 1.2 miles (1.9 km) | 75 yards (69 m) | A second tornado struck Marytown, damaging farm crops.[13] | |
| F0 | S ofCharlesburg | Calumet | WI | 00:10 | 0.1 miles (160 m) | 25 yards (23 m) | Brief tornado flattened two wheat fields.[14] | |
| F0 | Oakfield | Fond du Lac | WI | 00:25 | 0.6 miles (0.97 km) | 50 yards (46 m) | Second tornado moved through portions of the damage path of the F5 tornado, picking up debris from the ground but did not cause any additional structural damage.[15] | |
| F0 | NW ofNorth Fond du Lac | Fond du Lac | WI | 00:27 | 0.2 miles (320 m) | 50 yards (46 m) | A barn, machinery and crops were damaged or destroyed.[16] | |
| F0 | NE ofLomira | Fond du Lac | WI | 00:55 | 0.1 miles (160 m) | 50 yards (46 m) | Brief tornado flattened portions of a corn field.[17] | |
| F1 | S ofBeechwood | Sheboygan | WI | 01:10 | 0.9 miles (1.4 km) | 150 yards (140 m) | Several homes and a few barns were damaged, along with crops.[18] | |
| F1 | Fredonia toHoly Cross to ESE ofDecker | Ozaukee | WI | 01:18 | 7.6 miles (12.2 km) | 125 yards (114 m) | Four barns, three machine sheds and a one-car garage were destroyed while six homes, a barn, three machine sheds and a garage were damaged. Several vehicles were also damaged or destroyed, as well as 500 acres (2.0 km2) of crops.[19] | |
| F0 | E ofKnellsville | Ozaukee | WI | 01:28 | 0.8 miles (1.3 km) | 75 yards (69 m) | This tornado spent most of its lifetime overLake Michigan, causing little to no damage.[20] |
Following the tornado outbreak, Wisconsin GovernorTommy Thompson declared a state of emergency forFond du Lac County, resulting in the deployment of theNational Guard to aid victims and clear debris.[3][21] In total, 47 of 320 homes were destroyed and 56 homes were heavily damaged, along with numerous businesses and churches. Damage estimates reached over US$40.4 million, marking the outbreak the costliest in state history.[4]
Despite the severity of the F5 tornado and the extensive destruction it caused, no fatalities were reported, and a total of 17 people were injured during the outbreak. In the time that followed, the community of Oakfield received significant financial support from individuals and businesses in the form of donations and loans to aid in the rebuilding process. Much of the area's tree canopy and ecological landscape were devastated by the tornado, but through the concerted efforts of area residents and fundraising initiatives, over $102,000 was raised, and more than 1,400 trees were planted.[21]
The 25th anniversary of the tornado was observed on July 18, 2021,[5] with a series of commemorative events being held, including a parade, an outdoor church service, village-wide open houses, and a display of photographs and first-hand accounts of the tornado at the Oakfield Public Library's story walk in Acorn Park.[21]